TL;DR: New conjugative transposons, carrying different ribosomal protection tet genes, have been identified and an increase in the number of antibiotic resistance genes linked to tet genes has been found and whether these new elements may help to spread the tet genes they carry to a wider bacterial host range is discussed.
Abstract: This mini-review summarizes the changes in the field of bacterial acquired tetracycline resistance (tet) and oxytetracycline (otr) genes identified since the last major review in 2001. Thirty-eight acquired tetracycline resistant (Tcr) genes are known of which nine are new and include five genes coding for energy-dependent efflux proteins, two genes coding for ribosomal protection proteins, and two genes coding for tetracycline inactivating enzymes. The number of inactivating enzymes has increased from one to three, suggesting that work needs to be done to determine the role these enzymes play in bacterial resistance to tetracycline. In the same time period, 66 new genera have been identified which carry one or more of the previously described 29 Tcr genes. Included in the new genera is, for the first time, an obligate intracellular pathogen suggesting that this sheltered group of bacteria is capable of DNA exchange with non-obligate intracellular bacteria. The number of genera carrying ribosomal protection genes increased dramatically with the tet(M) gene now identified in 42 genera as compared with 24 and the tet(W) gene found in 17 new genera as compared to two genera in the last major review. New conjugative transposons, carrying different ribosomal protection tet genes, have been identified and an increase in the number of antibiotic resistance genes linked to tet genes has been found. Whether these new elements may help to spread the tet genes they carry to a wider bacterial host range is discussed.
TL;DR: Soil microorganisms that produce the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase promote plant growth by sequestering and cleaving plant-produced ACC, and thereby lowering the level of ethylene in the plant.
Abstract: Soil microorganisms that produce the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase promote plant growth by sequestering and cleaving plant-produced ACC, and thereby lowering the level of ethylene in the plant. Decreased ethylene levels allows the plant to be more resistant to a wide variety of environmental stresses. Here, the biochemistry of ACC deaminase; the environmental distribution, regulation, evolution and expression of ACC deaminase genes; and information regarding the effect of this enzyme on different plants is documented and discussed.
TL;DR: Silicon possesses unique biochemical properties that may explain its bioactivity as a regulator of plant defense mechanisms, and may interact with several key components of plant stress signaling systems leading to induced resistance.
Abstract: Silicon (Si) is a bioactive element associated with beneficial effects on mechanical and physiological properties of plants. Silicon alleviates abiotic and biotic stresses, and increases the resistance of plants to pathogenic fungi. Several studies have suggested that Si activates plant defense mechanisms, yet the exact nature of the interaction between the element and biochemical pathways leading to resistance remains unclear. Silicon possesses unique biochemical properties that may explain its bioactivity as a regulator of plant defense mechanisms. It can act as a modulator influencing the timing and extent of plant defense responses in a manner reminiscent of the role of secondary messengers in induced systemic resistance; it can also bind to hydroxyl groups of proteins strategically involved in signal transduction; or it can interfere with cationic co-factors of enzymes influencing pathogenesis-related events. Silicon may therefore interact with several key components of plant stress signaling systems leading to induced resistance.
TL;DR: Real-time, quantitative PCR assays for the detection of Bifidobacterium spp.
Abstract: To determine the influence of either exclusive breast-feeding or formula feeding on both composition and quantity of the gut microbiota in infants, we have developed real-time, quantitative PCR assays for the detection of Bifidobacterium spp. and Clostridium difficile. Furthermore, we have monitored the prevalence and counts of Escherichia coli by applying a previously described real-time PCR assay. We found all 100 infants tested to be colonized by Bifidobacterium spp. The bifidobacterial counts were comparable between the 50 breast-fed and 50 formula-fed infants with median values of 10.56 log10 and 10.24 log10 CFU g(-1) wet weight faeces, respectively. C. difficile was detected in 14% of the breast-fed and 30% of the formula-fed infants. In addition, the C. difficile counts were significantly lower in breast-fed infants than in the formula-fed group (median values of 3.28 log10 and 7.43 log10 CFU g(-1), respectively; p=0.03). The prevalence of E. coli in the breast-fed and formula-fed group was 80% and 94%, respectively. Also, the E. coli counts in colonized infants was significantly lower in the breast-fed infants than in the formula-fed group (median values of 9.11 log10 and 9.57 log10 CFU g(-1), respectively; p=0.004). We conclude that the prevalence and counts of C. difficile as well as E. coli are significantly lower in the gut microbiota of breast-fed infants than in that of formula-fed infants, whereas the prevalence and counts of Bifidobacterium spp. is similar among both groups.
TL;DR: The behaviour of almost all the tested strains isolated from Parmigiano Reggiano cheese resulted analogous to that showed by L. GG, and an important prerequisite of probiotic interest, such as the capability to survive at low pH and in presence of bile salts.
Abstract: This study aimed to compare phenotypic and genetic characteristics of Lactobacillus rhamnosus strains isolated at the end of the ripening of Parmigiano Reggiano cheese and to investigate an important prerequisite of probiotic interest, such as the capability to survive at low pH and in presence of bile salts. The use of API 50 CH, RAPD-PCR analysis and species-specific PCR allowed to ascertain the identity of 63 L. rhamnosus strains. Three L. rhamnosus strains isolated from Parmigiano Reggiano cheese, L. rhamnosus ATCC 7469T and the commercial strain L. GG were assayed to estimate the resistance to various stress factors reproducing in vitro some conditions of the gastro-intestinal environment such as low pH and different amounts of bile salts and acids. The behaviour of almost all the tested strains isolated from Parmigiano Reggiano cheese resulted analogous to that showed by L. GG.
TL;DR: This minireview summarizes recent advances in understanding the structure and function of the norovirus proteins and provides speculation about what roles they may play in the virus replication cycle.
Abstract: Noroviruses are positive strand RNA viruses that have received increased attention in recent years because their role as etiologic agents in acute gastroenteritis outbreaks is now clearly established. Much has been learned about the epidemiology of these viruses and the extent of genetic diversity among circulating strains. In contrast, progress on understanding the basic mechanisms of virus replication has been far slower due to the inability to cultivate virus in the laboratory. Despite this limitation, significant progress has been made in defining some basic functions of the norovirus proteins, and the structures of two have been solved to near atomic resolution. This minireview summarizes these recent advances in understanding the structure and function of the norovirus proteins and provides speculation about what roles they may play in the virus replication cycle.
TL;DR: A comprehensive detection system for 18 kinds of classical and newly described staphylococcal superantigenic toxin genes using four sets of multiplex PCR is described and analysis of the relationship between toxin genotypes and toxin genes encoding profiles of mobile genetic elements suggests its possible role in determining superantIGT genotypes in S. aureus.
Abstract: We describe a comprehensive detection system for 18 kinds of classical and newly described staphylococcal superantigenic toxin genes using four sets of multiplex PCR. Superantigenic toxin genotyping of Staphylococcus aureus for 69 food poisoning isolates and 97 healthy human nasal swab isolates revealed 32 superantigenic toxin genotypes and showed that many S. aureus isolates harbored multiple toxin genes. Analysis of the relationship between toxin genotypes and toxin genes encoding profiles of mobile genetic elements suggests its possible role in determining superantigenic toxin genotypes in S. aureus as combinations of toxin gene-encoding mobile genetic elements.
TL;DR: The production of monoterpenes, which elicit a floral aroma in wine, by strains of the yeast Saccharomyces cerevisiae is reported, and an alternative pathway for terpene biosynthesis not previously described in yeast is discussed.
Abstract: This paper reports the production of monoterpenes, which elicit a floral aroma in wine, by strains of the yeast Saccharomyces cerevisiae. Terpenes, which are typical components of the essential oils of flowers and fruits, are also present as free and glycosylated conjugates amongst the secondary metabolites of certain wine grape varieties of Vitis vinifera. Hence, when these compounds are present in wine they are considered to originate from grape and not fermentation. However, the biosynthesis of monoterpenes by S. cerevisiae in the absence of grape derived precursors is shown here to be of de novo origin in wine yeast strains. Higher concentration of assimilable nitrogen increased accumulation of linalool and citronellol. Microaerobic compared with anaerobic conditions favored terpene accumulation in the ferment. The amount of linalool produced by some strains of S. cerevisiae could be of sensory importance in wine production. These unexpected results are discussed in relation to the known sterol biosynthetic pathway and to an alternative pathway for terpene biosynthesis not previously described in yeast.
TL;DR: This study shows for the first time that the passaged inoculum is virulent irrespective of the original culture medium or insect host and it is postulate that starvation conditions, whether in vivo or in vitro, results in de-repression of Pr1 and that elevated levels of this enzyme enhance fungal virulence.
Abstract: Nutrition influenced growth, sporulation and virulence of the insect pathogenic fungus, Metarhizium anisopliae. Virulent conidia were produced on susceptible insect hosts, 1% yeast extract, 2% peptone, osmotic stress medium (OSM) and CN 10:1 medium. Several strain independent markers were identified that could be used to predict the virulence of M. anisopliae conidia. Virulent conidia typically had high levels of spore bound Pr1, an important cuticle degrading protease, and high germination rates. We also show for the first time that virulent conidia have an endogenous CN ratio below 5.2:1. Real Time PCR revealed that virulent conidia from insects contained significantly higher levels of transcripts of pr1 A and other pathogenicity-related genes than inoculum from artificial media. Of the artificial media studied, 1% yeast extract medium yielded the most virulent conidia, these had higher levels of transcripts of these pathogenicity-related genes than the least virulent conidia from the high conidia yielding CN 35:1 medium (=SDA), however, the levels were significantly lower than those in insect-derived conidia. Our study shows for the first time that the passaged inoculum is virulent irrespective of the original culture medium or insect host. Virulent conidia were consistently produced on OSM even though growth and sporulation were poor. We postulate that starvation conditions, whether in vivo or in vitro, results in de-repression of Pr1 and that elevated levels of this enzyme enhance fungal virulence.
TL;DR: Different degradation rates of chlorpyrifos in six types of treated soils suggested that soils used for cabbage growing in combination with inoculation of strain DSP3 showed enhanced microbial degradation of chlor pyrifo.
Abstract: A bacterium, isolated from contaminated soils around a chemical factory and named strain DSP3 was capable of biodegrading both chlorpyrifos and 3,5,6-trichloro-2-pyridinol. Based on the results of phenotypic features, phylogenetic similarity of 16S rRNA gene sequences, DNA G + C content, and DNA homology between strain DSP3 and reference strains, strain DSP3 was identified as Alcaligenes faecalis. Chlorpyrifos was utilized as the sole source of carbon and phosphorus by strain DSP3. We examined the role of strain DSP3 in the degradation of chlorpyrifos and 3,5,6-trichloro-2-pyridinol under different culture conditions. Parathion and diazinon could also be degraded by strain DSP3 when provided as the sole sources of carbon and phosphorus. An addition of strain DSP3 (108 cells g−1) to soil with chlorpyrifos (100 mg kg−1) resulted in a higher degradation rate than the one obtained from non-inoculated soils. Different degradation rates of chlorpyrifos in six types of treated soils suggested that soils used for cabbage growing in combination with inoculation of strain DSP3 showed enhanced microbial degradation of chlorpyrifos.
TL;DR: This review presents the current model on mechanisms of invasion of the colonic epithelium by these bacteria and focuses on their pathogenicity factors, particularly the virulence plasmid-encoded type III secretion system.
Abstract: Bacteria of Shigella spp. (S. boydii, S. dysenteriae, S. flexneri and S. sonnei) and enteroinvasive Escherichia coli (EIEC) are responsible for shigellosis in humans, a disease characterized by the destruction of the colonic mucosa that is induced upon bacterial invasion. Shigella spp. and EIEC strains contain a virulence plasmid of approximately 220 kb that encodes determinants for entry into epithelial cells and dissemination from cell to cell. This review presents the current model on mechanisms of invasion of the colonic epithelium by these bacteria and focuses on their pathogenicity factors, particularly the virulence plasmid-encoded type III secretion system.
TL;DR: The present results from the chronically oil-contaminated landfarming soil support the suggested importance of Nitrosospira-like AOB in terrestrial environments.
Abstract: Chemolithotrophic ammonia-oxidising bacteria (AOB) present in oil-contaminated landfarming soil were studied over two growing seasons in 1999 and 2000. The number of AOB (4–9 · 10 5 cells g � 1 of dry soil) determined with the quantitative polymerase chain reaction (real-time PCR) and the rate of potential ammonium oxidation ð0.05–0.28 l gN O � – Ng � 1 of dry soil h � 1 Þ indicated the presence of stable AOB populations. Denaturing gradient gel electrophoresis (DGGE) profiling and sequence analysis of PCRamplified AOB 16S rRNA genes showed dominance of Nitrosospira-like sequences in clusters 2 and 3. The present results from the chronically oil-contaminated landfarming soil support the suggested importance of Nitrosospira-like AOB in terrestrial environments.
TL;DR: The Chaetomium globosum strain F0142, which was isolated from barnyard grass, showed potent disease control efficacy against rice blast and wheat leaf rust and moderate control of tomato late blight.
Abstract: The Chaetomium globosum strain F0142, which was isolated from barnyard grass, showed potent disease control efficacy against rice blast (Magnaporthe grisea) and wheat leaf rust (Puccinia recondita). Two antifungal substances were purified from broth from this organism and identified as chaetoviridins A and B. Chaetoviridin A exhibited higher antifungal activity than chaetoviridin B against plant pathogenic fungi both in vitro and in vivo. Treatment with chaetoviridin A at 62.5 μg/mL suppressed the development of rice blast and wheat leaf rust by over 80%. The molecule also exhibited moderate control of tomato late blight, resulting in 50% control following the application of 125 μg/mL chaetoviridin A.
TL;DR: It seems likely that raw bovine milk used in the preparation of mashed potato contained S. aureus that subsequently produced sufficient SEH in the mashed potato to cause food poisoning.
Abstract: Mashed potato made with raw bovine milk was suspected to have been the source of a food poisoning outbreak. Almost 8 x 10(8)Staphylococcus aureus CFU g(-1) were detected in the mashed potato. S. aureus was also found in bulk milk from the farm that had supplied milk for the mashed potato. Isolates from mashed potato and bulk milk were positive for the gene encoding staphylococcal enterotoxin H (seh), and the corresponding protein toxin, SEH, was detected by ELISA in the mashed potato. Production of SEH by S. aureus isolates from mashed potato (n = 4) and bulk milk (n = 4) was also demonstrated by ELISA. Sequencing of seh from one mashed potato isolate and one bulk milk isolate confirmed that the gene was a variant seh, and that the genes in both isolates were identical. Macrorestriction of chromosomal DNA with Sma1 followed by pulsed-field gel electrophoresis of seh-positive S. aureus from mashed potato and bulk milk revealed indistinguishable banding patterns between isolates from both sources. It seems likely that raw bovine milk used in the preparation of mashed potato contained S. aureus that subsequently produced sufficient SEH in the mashed potato to cause food poisoning.
TL;DR: This review focuses on the well studied perylenequinone toxin, cercosporin, produced by species in the genus Cercospora, with the characterization of genes encoding a polyketide synthase and a major facilitator superfamily transporter representing the first and last steps of the biosynthetic pathway.
Abstract: Several genera of plant pathogenic fungi produce photoactivated perylenequinone toxins involved in pathogenesis of their hosts. These toxins are photosensitizers, absorbing light energy and generating reactive oxygen species that damage the membranes of the host cells. Studies with toxin-deficient mutants and on the involvement of light in symptom development have documented the importance of these toxins in successful pathogenesis of plants. This review focuses on the well studied perylenequinone toxin, cercosporin, produced by species in the genus Cercospora. Significant progress has been made recently on the biosynthetic pathway of cercosporin, with the characterization of genes encoding a polyketide synthase and a major facilitator superfamily transporter, representing the first and last steps of the biosynthetic pathway, as well as important regulatory genes. In addition, the resistance of Cercospora fungi to cercosporin and to the singlet oxygen that it generates has led to the use of these fungi as models for understanding cellular resistance to photosensitizers and singlet oxygen. These studies have shown that resistance is complex, and have documented a role for transporters, transient reductive detoxification, and quenchers in cercosporin resistance. 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.
TL;DR: Results indicate that the gnd mutation is responsible for diminished allosteric regulation and contributes to redirection of more carbon to the pentose phosphate pathway that was identified as the primary source for NADPH essential for L-lysine biosynthesis, thereby leading to improved product formation.
Abstract: Toward more efficient L-lysine production, we have been challenging genome-based strain breeding by the approach of assembling only relevant mutations in a single wild-type background. Following the creation of a new L-lysine producer Corynebacterium glutamicum AHP-3 that carried three useful mutations (lysC311, hom59, and pyc458) on the relevant downstream pathways, we shifted our target to the pentose phosphate pathway. Comparative genomic analysis for the pathway between a classically derived L-lysine producer and its parental wild-type identified several mutations. Among these mutations, a Ser-361-->Phe mutation in the 6-phosphogluconate dehydrogenase gene (gnd) was defined as a useful mutation for L-lysine production. Introduction of the gnd mutation into strain AHP-3 by allelic replacement led to approximately 15% increased L-lysine production. Enzymatic analysis revealed that the mutant enzyme was less sensitive than the wild-type enzyme to allosteric inhibition by intracellular metabolites, such as fructose 1,6-bisphosphate, D-glyceraldehyde 3-phosphate, phosphoribosyl pyrophosphate, ATP, and NADPH, which were known to inhibit this enzyme. Isotope-based metabolic flux analysis demonstrated that the gnd mutation resulted in 8% increased carbon flux through the pentose phosphate pathway during L-lysine production. These results indicate that the gnd mutation is responsible for diminished allosteric regulation and contributes to redirection of more carbon to the pentose phosphate pathway that was identified as the primary source for NADPH essential for L-lysine biosynthesis, thereby leading to improved product formation.
TL;DR: This report demonstrates the disruption of B. bronchiseptica biofilms by rhamnolipids secreted from Pseudomonas aeruginosa, and suggests that biosurfactants such as rhamNolipid may be utilized as antimicrobial agents for removing Bordetella bio Films.
Abstract: We have previously reported that the respiratory pathogen Bordetella bronchiseptica can form biofilms in vitro. In this report, we demonstrate the disruption of B. bronchiseptica biofilms by rhamnolipids secreted from Pseudomonas aeruginosa. This suggests that biosurfactants such as rhamnolipids may be utilized as antimicrobial agents for removing Bordetella biofilms.
TL;DR: The finding that, among the investigated adhesins, fibronECTin-adhesins are present in the majority of the implant associated S. aureus clinical isolates encourages the development of strategies to specifically block the interaction of bacteria with matrix fibronectin by antagonist ligands.
Abstract: Here are reported data on virulence determinants of Staphylococcus aureus from orthopedic surgical infections, emphasizing on the genes encoding fibronectin (fnbA, fnbB) and collagen (cna) adhesins. 191 S. aureus strains from orthopedic infections (53 from internal fixation devices, 29 external fixation devices, 15 knee arthroprostheses, 30 hip arthroprostheses, 45 surgical reconstruction and 19 non-associated to medical devices) were investigated for the presence of the genes of the collagen-binding protein Cna and of the two fibronectin-binding proteins, FnbA and FnbB. 87 (46%) strains were found to be cna+ without significant variations across the different surgical categories considered. Conversely, the fnbA and the fnbB genes were almost always present in all surgical categories. The finding that, among the investigated adhesins, fibronectin-adhesins are present in the majority of the implant associated S. aureus clinical isolates encourages the development of strategies to specifically block the interaction of bacteria with matrix fibronectin by antagonist ligands.
TL;DR: Conidial anastomosis tubes (CATs) can be recognized in 73 species of filamentous fungi covering 21 genera, and develop in culture and in host-pathogen systems, and are potential agents of gene exchange between individuals of the same and different species.
Abstract: Conidial anastomosis tubes (CATs) can be recognized in 73 species of filamentous fungi covering 21 genera, and develop in culture and in host-pathogen systems. They have been shown to be morphologically and physiologically distinct from germ tubes in Colletotrichum and Neurospora, and under separate genetic control in Neurospora. CATs are short, thin, usually unbranched and arise from conidia or germ tubes. Their formation is conidium-density dependent, and CATs grow towards each other. MAP kinase mutants of Neurospora are blocked in CAT induction. Nuclei pass through fused CATs and are potential agents of gene exchange between individuals of the same and different species. CAT fusion may also serve to improve the chances of colony establishment.
TL;DR: A procedure combining a cell extraction method and Fluorescence In Situ Hybridization for molecular monitoring and quantification of bacteria in soil and aquifer samples is presented and is promising for in situ detection of indigenous bacterial communities in complex samples.
Abstract: In the present study a procedure combining a cell extraction method and Fluorescence In Situ Hybridization (FISH) for molecular monitoring and quantification of bacteria in soil and aquifer samples is presented. FISH was applied to bacterial cells extracted from the matrix by density gradient centrifugation. This separation method was applied to soil and aquifer samples and produced high cell recovery of 76.5%± 4.4 and 78.0%± 3.2, respectively. FISH, performed on the harvested cells, permitted a perfect visualization and quantification of bacteria. This approach is therefore promising for in situ detection of indigenous bacterial communities in complex samples.
TL;DR: Two species-specific PCR assays for rapid and accurate detection of the pathogenic fungi Fusarium oxysporum f.
Abstract: We developed two species-specific PCR assays for rapid and accurate detection of the pathogenic fungi Fusarium oxysporum f. sp. niveum and Mycosphaerella melonis in diseased plant tissues and soil. Based on differences in internal transcribed spacer (ITS) sequences of Fusarium spp. and Mycosphaerella spp., two pairs of species-specific primers, Fn-1/Fn-2 and Mn-1/Mn-2, were synthesized. After screening 24 isolates of F. oxysporum f. sp. niveum, 22 isolates of M. melonis, and 72 isolates from the Ascomycota, Basidiomycota, Deuteromycota, and Oomycota, the Fn-1/Fn-2 primers amplified only a single PCR band of approximately 320 bp from F. oxysporum f. sp.niveum, and the Mn-1/Mn-2 primers yielded a PCR product of approximately 420 bp from M. melonis. The detection sensitivity with primers Fn-1/Fn-2 and Mn-1/Mn-2 was 1 fg of genomic DNA. Using ITS1/ITS4 as the first-round primers, combined with either Fn-1/Fn-2 and or Mn-1/Mn-2, two nested PCR procedures were developed, and the detection sensitivity increased 1000-fold to 1 ag. The detection sensitivity for the soil pathogens was 100-microconidia/g soil. A duplex PCR method, combining primers Fn-1/Fn-2 and Mn-1/Mn-2, was used to detect F. oxysporum f. sp. niveum and M. melonis in plant tissues infected by the pathogens. Real-time fluorescent quantitative PCR assays were developed to detect and monitor the pathogens directly in soil samples. The PCR-based methods developed here could simplify both plant disease diagnosis and pathogen monitoring as well as guide plant disease management.
TL;DR: It is demonstrated that TTSS3 is required for the full virulence of B. pseudomallei in the hamster model of infection and the virulent mutants deficient in several putative T TSS3 effector molecules are examined.
Abstract: Burkholderia pseudomallei, the etiological agent of melioidosis, is an animal pathogen capable of inducing a highly fatal septicemia. B. pseudomallei possesses three type III secretion system (TTSS) clusters, two of which (TTSS1 and TTSS2) are homologous to the TTSS of the plant pathogen Ralstonia solanacearum, and one (TTSS3) is homologous to the Salmonella SPI-1 mammalian pathogenicity island. We have demonstrated that TTSS3 is required for the full virulence of B. pseudomallei in a hamster model of infection. We have also examined the virulence of B. pseudomallei mutants deficient in several putative TTSS3 effector molecules, and found no significant attenuation of B. pseudomallei virulence in the hamster model.
TL;DR: First evidence was provided that the cell division and the localization of GFP-PHA synthase foci are in vivo co-located and PHA granules with twofold increased diameter were formed.
Abstract: For the first time a functional protein was fused to a PHA synthase resulting in PHA granule formation and display of the respective function at the PHA granule surface. The GFP reporter protein was N-terminally fused to the class I PHA synthase of Cupriavidus necator (PhaC) and the class II PHA synthase of Pseudomonas aeruginosa PAO1 (PhaC1), respectively, while maintaining PHA synthase activity and PHA granule formation. Fluorescence microscopy studies of GFP–PHA synthase attached to emerging PHA granules indicated that emerging PHA granules locate to cell poles and to midcell representing the future cell poles. A rapid oscillating movement of GFP–PHA synthase foci from pole to pole was observed. In cell division impaired Escherichia coli, PHA granules were localized between nucleoids at regular spacing suggesting that nucleoid occlusion occurred. Accordingly, anucleate regions of the E. coli mukB mutant showed no regular spacing, but PHA granules with twofold increased diameter were formed. First evidence was provided that the cell division and the localization of GFP–PHA synthase foci are in vivo co-located.
TL;DR: Direct measurement of JHE activity, however, shows that the Pir proteins are not able to metabolise JH, and leaves the mode of action of these interesting proteins uncertain.
Abstract: The genome of the insect pathogen Photorhabdus luminescens strain TT01 contains numerous genes predicting toxins and proteases. Within the P. luminescens TT01 genome, the products of two loci, plu 4093-plu 4092 and plu 4437-plu 4436, show oral insecticidal activity against both moth and mosquito larvae. The proteins encoded by these loci, here termed ‘Photorhabdus insect related’ (Pir) proteins A and B, show similarity both to δ-endotoxins from Bacillus thuringiensis (Bts) and a developmentally regulated protein from a beetle, Leptinotarsa decemlineata. The beetle protein has been inferred to possess juvenile hormone esterase (JHE) activity due to its developmentally regulated pattern of expression and the Photorhabdus proteins PirA and PirB have been proposed to be mimics of insect JHEs that can disrupt insect metamorphosis by metabolizing the insect growth regulator juvenile hormone (JH) [Nat. Biotechnol. 21 (2003) 1307–1313]. Here we confirm that, when injected together, PirA and PirB from two different Photorhabdus strains have insecticidal activity against caterpillars of the moth Galleria mellonella but show no oral activity against a second moth species Manduca sexta. Direct measurement of JHE activity, however, shows that the Pir proteins are not able to metabolise JH. These data show that the Pir proteins have no JHE activity, as suggested, but leave the mode of action of these interesting proteins uncertain.
TL;DR: The results indicate that rpoS gene is involved in tolerance to antibiotics in P. aeruginosa during the stationary phase and heat stress, however, under osmotic stress, tolerance to biapenem was not dependent on the r poS gene.
Abstract: The alternative sigma factor, RpoS has been described as a central regulator of many stationary phase-inducible genes and a master stress-response regulator under various stress conditions. We constructed an rpoS mutant in Pseudomonas aeruginosa and investigated the role of rpoS gene in antibiotic tolerance. The survival of the rpoS mutant cells in stationary phase was ∼70 times lower when compared with that of the parental strain at 37 °C for 2 h after the addition of biapenem. For imipenem, the survival was ∼40 times lower. Heat stress promoted an increase in the survival of the parental strain to biapenem, but the same was not found to be the case for the rpoS mutant. Our results indicate that rpoS gene is involved in tolerance to antibiotics in P. aeruginosa during the stationary phase and heat stress. However, under osmotic stress, tolerance to biapenem was not dependent on the rpoS gene.
TL;DR: This minireview focuses on recent findings about host susceptibility and the way powdery mildew fungi might induce it.
Abstract: Plants are resistant to most potentially pathogenic microbes. This forces plant pathogens to develop sophisticated strategies to overcome basic plant resistance, either by masking intrusion or by suppression of host defences. This is particularly true for fungal pathogens, which establish long lasting interactions with living host tissue, without causing visible damage to invaded cells. The interactions of cereal crops and Arabidopsis with powdery mildew fungi are model systems for understanding host resistance. Currently, these systems are also promoting the understanding of fungal infection by identifying fungal pathogenicity and virulence factors and host target sites. This minireview focuses on recent findings about host susceptibility and the way powdery mildew fungi might induce it.
TL;DR: The obtained profile for IAA synthesis coincides with the expression of the indole-3-pyruvate decarboxylase gene (ipdC), encoding a key enzyme in the IAA biosynthesis of A. brasilense.
Abstract: Batch and fed batch cultures of Azospirillum brasilense Sp245 were conducted in a bioreactor. Growth response, IAA biosynthesis and the expression of the ipdC gene were monitored in relation to the environmental conditions (temperature, availability of a carbon source and aeration). A. brasilense can grow and produce IAA in batch cultures between 20 and 38 C in a standard minimal medium (MMAB) containing 2.5 g l � 1 L-malate and 50 l gm l � 1 tryptophan. IAA synthesis requires depletion of the carbon source from the growth medium in batch culture, causing growth arrest. No significant amount of IAA can be detected in a fed batch culture. Varying the concentration of tryptophan in batch experiments has an effect on both growth and IAA synthesis. Finally we confirmed that aerobic growth inhibits IAA synthesis. The obtained profile for IAA synthesis coincides with the expression of the indole-3-pyruvate decarboxylase gene (ipdC), encoding a key enzyme in the IAA biosynthesis of A. brasilense. 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.
TL;DR: A novel disease of crayfish Procambarus clarkii appeared in the summer of 2004 in freshwater aquaculture in Jiangsu province of China and the agent was unique in having a helical morphology and rotary motility and was found in haemolymph, muscles, nerves and connective tissues by smear method and TEM.
Abstract: A novel disease of crayfish Procambarus clarkii appeared in the summer of 2004 in freshwater aquaculture in Jiangsu province of China. Light and transmission electron microscopy (TEM), molecular biological methods and in vitro culture were used to identify the pathogen. The agent was unique in having a helical morphology and rotary motility as observed by phase-contrast light microscopy and was found in haemolymph, muscles, nerves and connective tissues by smear method and TEM. Ultra-thin sections under TEM revealed the wall-free membrane of the microbe. The agent could pass through membrane filters with pores 220 nm in diameter and was cultivated in vitro in M1D medium. 16S rDNA of the crayfish pathogen was amplified by PCR using primers specific for Spiroplasma-specific 16S rDNA. The resultant 271 bp PCR product showed 99% identity with Spiroplasma mirum 16S rDNA, having a close relationship with the spiroplasma from the Chinese mitten crab Eriocheir sinensis. This is the second time a spiroplasma has been found in a freshwater crustacean. The 271 bp PCR product was also amplified from the bottom mud in the ponds associated with the disease. The PCR molecular method is an effective way to detect spiroplasma in freshwater environment. The results from this study are significant in expanding the host range of spiroplasma and freshwater ecology.
TL;DR: In the recombinant, overexpression of hydA abolished lactic acid production and increased acetic acid production by over-oxidation of NADH, which is required for reduction of pyruvic acid to lactic Acid in the wild-type.
Abstract: A [Fe]-hydrogenase gene (hydA) was cloned from Clostridium paraputrificum M-21 in Escherichia coli using a conserved DNA sequence of clostridial hydrogenase genes amplified by PCR as the probe. The hydA gene consisted of an open reading frame of 1749 bp encoding 582 amino acids with an estimated molecular mass of 64,560 Da. It was ligated into a shuttle vector, pJIR751, originally constructed for Clostridium perfringens and E. coli, and expressed in C. paraputrificum. Hydrogen gas productivity of the recombinant increased up to 1.7-fold compared with the wild-type. In the recombinant, overexpression of hydA abolished lactic acid production and increased acetic acid production by over-oxidation of NADH, which is required for reduction of pyruvic acid to lactic acid in the wild-type.
TL;DR: A loop-mediated isothermal amplification (LAMP) method for detecting Shigella and enteroinvasive Escherichia coli efficiently detected the ipaH gene within 2 h at a minimal amount of bacteria (8 CFU) per reaction.
Abstract: Here we report a loop-mediated isothermal amplification (LAMP) method for detecting Shigella and enteroinvasive Escherichia coli. The target for this LAMP method is the ipaH gene which is carried by both of the pathogens. The LAMP method efficiently detected the gene within 2 h at a minimal amount of bacteria (8 CFU) per reaction.