Pediococcus

Abstract: Lactic Acid Bacteria (LAB) commonly used as starter cultures in food technology are known to manufacture antimicrobial products having great potential. The aim of this study is isolation of lactic acid bacterial strain which has been potential for lactic acid production, to identify, characterize it and to optimize culture conditions for the process. For this study, we have isolated different strains of Lactic Acid Bacteria (LAB) from dairy sludge samples which were collected from 3 different dairy plant of Gujarat, (India). Therefore, characterization of isolated strains through morphological, physiological, biochemical and carbohydrate fermentation test were done. Lactic Acid Bacteria (LAB) are a group of Gram-positive, non- spore forming, cocci or rod shaped, catalase-negative and fastidious organisms, considered as ‘Generally Recognized As Safe’ (GRAS) organism. For isolation, samples were serially diluted and plated on MRS agar (DE MAN, ROGOSA and SHARPE agar. HI Media) Plate. Well-isolated colonies with typical characteristics were picked from each plate and were further sub cultured until pure isolates were obtained and transferred to MRS broth (HI Media) for further experiments. Identification of lactic acid bacteria belongs to family Lactobacillaceae was done first at genus level in the Lactobacillus, Lactococcus, Streptococcus, Leuconostoc, Pediococcus. Lactobacillus is rod shape and Streptococcus, Leuconostoc, Pediococcus are cocci shape. Most of them are used in dairy starter culture, present in raw milk, milk-loving bacteria. Isolated colony was identified by gram-staining, gram +ve and rod shape strain showed confirmation of lactobacillus . L.bulgaricus and Streptococcus thermophilus were found as the most dominant species in common sludge unit. While L.acidophillus was found as dominant species along with the L.bulgaricus and Streptococcus thermophilus in the sludge of pro biotic acidophilus butter milk manufacturing unit and L.casei, L.helveticus, L.brevis, L.lactis were present as the dominant species in the cheese manufacturing unit along with the L.bulgaricus and Streptococcus thermophilus. Selected microbial isolates obtained in this study will be used for production of lactic acid acts as monomer for the synthesis of biodegradable polymer on my future study.

Abstract: The control of wine microbial population during and beyond fermentation is of huge importance for wine quality. Lactic acid bacteria (LAB) in wine are responsible for malolactic fermentation (MLF) which can be desired in some cases and undesirable in others. Some LAB do not perform MLF and their uncontrolled growth could contribute to severe wine spoilage such as undesired flavours. Their identification and detection is considered crucial for numerous biotechnological applications in food fermentations, where, through acidification and secretion of bacteriocins, they contribute to reduce food spoilage and growth of pathogenic microorganisms. LAB have traditionally been classified using morphological or biochemical features. Primary isolation, biochemical identification and phenotypic analysis are laborious, time consuming and inaccurate and often lead to misidentification within some genera such as Pediococcus. Molecular identification based on suitable marker genes could be an attractive alternative to conventional morphological and biochemical methods. We assessed here the applicability of four housekeeping genes recA, rplB, pyrG and leuS in combination with the mle gene in multi-loci sequence typing (MLST) of Pediococcus parvulus and Pediococcus damnosus. Sequencing and comparative analysis of sequence data were performed on 19 strains collected during wine fermentation. A combination of these five marker genes allowed for a clear differentiation of the strains analysed, indicating their applicability in molecular typing. Analysis of the observed nucleotide polymorphisms allowed designing highly discriminative primers for a multi-loci sequence typing (MLST) method that proved successful in detecting a particular isolate or sequence type of P. parvulus when using either conventional PCR or Real Time PCR.

Abstract: Bacteriocins are ribosomally synthesized peptides having considerable potential as a food preservative because of their strong antagonistic activity against many food spoilage and pathogenic organisms. Bacteriocins from Pediococcus pentosaceous isolates, DFR-JJ1 and DFR-JJ6, were purified using cold-acetone precipitation, cell adsorption-desorption and gel permeation chromatography techniques. Cold-acetone fractionation resulted in higher yields of bacteriocins, but the specific activity and fold purification were higher for cell adsorption-desorption and gel permeation chromatography. Both bacteriocins JJ1 and JJ6 exhibited broad inhibitory spectrum against foodborne pathogens and spoilage microorganisms, including some Gram-negative bacteria. Amylase, lipase and catalase did not alter the antimicrobial activity but proteolytic enzymes inactivated these bacteriocins. They were heat stable and exhibited activity in a pH range of 2–8 with maximum activity between pH 4.0 and 5.0. Molecular weights of bacteriocin JJ1 and JJ6 were found to be ∼4.95 and 4.3 kDa, respectively. PRACTICAL APPLICATIONS Bacteriocins of lactic acid bacteria have been found to kill or inhibit the growth of foodborne pathogens and spoilage microflora, and hence, can be used as natural preservatives in the production of foods with enhanced shelf life and/or safety. With the emergence of antibiotic-resistant Gram-positive pathogenic bacteria, the possibility of bacteriocins as supplements or replacements for antibiotics for therapeutic use is also being considered. Of all the antimicrobial peptides, very few have been used as preservatives in the food industry and/or as antibiotic substances in medicine. However, an increasing number of bacteriocins are being tested in model systems, some of them show promising results and may reach commercial acceptance in the near future. In the present study, two bacteriocins from Pediococcus pentosaceous strains were purified, which inhibited the growth of Staphylococcus aureus in liquid medium and Salmonella typhimurium in orange juice, justifying their potential as food biopreservatives.

Abstract: The invention relates to lactic bacterial strains of the genera Lactobacillus ands Pediococcus which are capable of initiating and carrying out a complete malolactic fermentation on direct introduction, in the dried, frozen or lyophilised state, without a previous acclimatisation step, at a concentration of between 106 and 5x107 UFC/ml, into a wine with an alcohol content of 10 % or more and an average or high pH level. The resistance to alcohol is apparent with an excellent survival rate on inoculation and a rapid start to the fermentation activity such that said strain i) converts at least 5 %, preferably at least 10 %, of the malic acid into lactic acid in 5 days after inoculation of the wine and ii) converts at least 10 %, preferably at least 25 %, of the malic acid into lactic acid within 10 days of the inoculation of the wine. The invention further relates to a method for malolactic conversion in a wine of average to high pH by direct inoculation wit a lactic bacterial preparation, comprising at least one of said strains in the course of or at the end of the alcoholic fermentation.