Abstract: The poor management of solid wastes in Tanzania urban centers is a chronic problem that has increasingly become a source of environmental pollution. Bioconversion offers a cheap and safe method of not only disposing these wastes, but also it has the potential to convert lignocellulosic wastes into usable forms such as reducing sugars that could be used as food. This paper reports a preliminary study on the physical characteristics, acid pretreatment, saccharification by cellulase from Trichoderma reesei and fermentation by Saccharomyces cerevisiae of the lignocellulosic component of the solid wastes collected from various dumping sites located in Kinondoni Municipality, Dar es Salaam city. The results showed that overall, the lignocellulosic component constitute about 50% of solid wastes dumped in the study areas. Maximum production of reducing sugars was obtained after 6 h of saccharification while highest concentrations of bioethanol were achieved after 48 h of fermentation. Microbial bioconversion of lignocellulose component yielded up to 21% bioethanol.

Abstract: The valorisation of glycerol produced in a constantly increasing amount as a by-product from fat processing becomes a serious problem for the related industry. The refining of this glycerol to pharmaceutical quality is energy-consuming and does not represent a cost-effective alternative, especially not for biodiesel producers. Anoth­ er possibility for valorisation of raw glycerol is the micro­ biological conversion into the important intermediate chemical 1,3-propanediol (1,3-PD). Currently, the polyal­ cohol is expensively obtained from petrochemical origin, but it is of growing interest mainly for modern fibre syn­ thesis. Within the European Union-funded research pro­ ject BIODIOL, an integrated bioconversion process for 1,3-PD production from raw glycerol is developed. Untreated glycerols from biodiesel industry are used as the main substrate. A new, wild-type strain and a tailor­ made strategy lead to 1,3-PD concentrations up to 100 g×L -1 . The process development is driven by both economical and ecological aspects. The utilisation of cheap substrate sources such as biodiesel and starch industry supports the sustainable approach. Thereby, the production costs of 1,3-PD can be reduced to an efficient and competitive level.

Abstract: Softwood residues are the most abundant feedstock available for bioconversion in many northern countries. However, the high costs for delignification and enzymatic hydrolysis currently deter commercialization of softwood bioconversion processes. This study evaluates the abilities of two novel fungal preparations (MSUBC1 and MSUBC2) and two commercial cellulase preparations (TR1 and TR2) to hydrolyze cellulose in Douglas-fir pretreated by steam explosion or ethanol organosolv process. MSUBC1 showed significantly better performance than the other preparations on both lignocellulosic substrates. In particular, MSUBC1 achieved >76% cellulose conversion for hydrolysis of steam-exploded Douglas-fir (∼44% lignin) after 72 h at low enzyme loading (10 filter paper units/g of cellulose) and without β-glucosidase supplementation.

Abstract: Economic barriers preventing commercialization of lignocellulose-toethanol bioconversion processes include the high cost of hydrolytic enzymes. One strategy for cost reduction is to improve the specific activities of cellulases by genetic engineering. However, screening for improved activity typically uses “ideal” cellulosic substrates, and results are not necessarily applicable to more realistic substrates such as pretreated hardwoods and softwoods. For lignocellulosic substrates, nonproductive binding and inactivation of enzymes by the lignin component appear to be important factors limiting catalytic efficiency. A better understanding of these factors could allow engineering of cellulases with improved activity based on reduced enzyme-lignin interaction (“weak lignin-binding cellulases”). To prove this concept, we have shown that naturally occurring cellulases with similar catalytic activity on a model cellulosic substrate can differ significantly in their affinities for lignin. Moreover, although cellulose-binding domains (CBDs) are hydrophobic and probably participate in lignin binding, we show that cellulases lacking CBDs also have a high affinity for lignin, indicating the presence of lignin-binding sites on the catalytic domain.

Abstract: The esterification of cinnamic acid (CA) and oleyl alcohol (OA) in organic solvent media by immobilized lipase Novozym 435 was optimized in terms of selected parameters, including the logarithm of the 1-octanol/water partition coefficient of the organic solvent (log P, 0.29-4.5), initial water activity (aw, 0.05-0.75), agitation speed (0-200rpm), temperature (35-65 ◦ C) and ratio of substrates (CA/OA, 1.0:0.5-1.0:6.0). The results showed that the more hydrophobic solvent mixtures and lower initial aw values resulted in a higher enzymatic activity and bioconversion yield. The most appropriate solvent medium and initial aw value was the mixture of iso-octane/2-butanone (85:15, v/v) and 0.05, respectively. The results also showed that an agitation speed of 150rpm and a reaction temperature of 55 ◦ Cw ere optimal for the reaction system. The activation energy (Ea) of the esterification reaction was calculated as 43.6kJmol −1 . The optimal ratio of CA to OA was 1.0:6.0, with the absence of any inhibition by OA. Using the optimized conditions, the maximum enzymatic activity was 390.3nmolg −1 min −1 , with a bioconversion yield of 100% after 12days of reaction. In addition, the electrospray ionization-mass spectroscopy analysis confirmed that the major end product of the esterification reaction was oleyl cinnamate.  2005 Society of Chemical Industry

Abstract: Submerged cultures of the ascomycete Chaetomium globosum oxidised the exogenous sesquiterpene (+)-valencene to nootkatone via the stereoselective generation of α-nootkatol. Inhibition experiments suggested that the first introduction of oxygen, the rate-limiting step of the bioconversion, may have been catalysed by a cytochrome-P450-monooxygenase. However, nootkatone was not the final metabolite: further flavour-active and inactive, non-volatile oxidation products were identified. (+)-Valencene and the flavour-active mono-oxyfunctionalised transformation products, α-nootkatol, nootkatone, and valencene-11,12-epoxide accumulated preferably inside the fungal cells. Di- and poly-oxygenated products, such as nootkatone-11,12-epoxide, were found solely in the culture medium, indicating an active transport of these metabolites into the extracellular compartment during (+)-valencene detoxification. These metabolic properties may have contributed to the high tolerance of the fungus towards the exogenous hydrocarbon.

Abstract: The generation of aroma compounds by carotenoid cleavage in the 9–10 position was studied, due to the importance of these compounds in the flavor and fragrance industry. The bioconversion of the carotenoid lutein to C13 norisoprenoids utilizing a microbial mixture composed of Trichosporon asahii and Paenibacillus amylolyticus was carried out by a fermentation process. Applying an experimental design methodology, the effects of nutritional factors on the production of aroma compounds present in the tobacco profile were studied. After an assessment of the significance of each nutritional factor, the levels of the variables yielding the maximum response were calculated. Glucose, tryptone, and yeast extract exerted a strong negative effect over the objective function, with glucose being the strongest. Lutein possessed a positive effect over the tobacco aroma production, while sodium chloride and trace elements showed no influence over the process. The yield attained after culture medium manipulation was almost ten-fold higher, compared with the base medium; and the aroma mixture was characterized as: 7,8-dihydro-β-ionol (95.2%), 7,8-dihydro-β-ionone (3.7%), and β-ionone (1.1%).

Abstract: A semi-continuous simultaneous saccharification and fermentation (SSF) process for the bioconversion of cellulose into ethanol and other organic chemicals is disclosed. The process provides for substantially higher substrate conversion at a given enzyme loading (or alternatively a lower enzyme loading used to achieve the same conversion) in a reactor operated according to a semi-continuous feeding protocol.

Abstract: Xylose-to-xylitol batch bioconversions from wheat straw hemicellulosic hydrolysate were carried out in Erlenmeyer flasks in order to assess the influence of medium composition (hydrolysate concentration, supplementation with ammonium sulphate, calcium chloride and rice bran extract, and initial pH) on xylitol production, productivity and yield. By using the screening design and the response surface methodologies, the statistically significant variables influencing the bioconversion were selected and linear models were fitted to the experimental data. According to the results, the best conditions to perform the bioconversion consisted in using a threefold concentrated hydrolysate supplemented with ammonium sulphate (1.0 g/l) and rice bran extract (5.0 g/l), whose pH was adjusted to 6.0 prior to inoculation. Under these conditions, a xylitol production of 24.17 g/l was observed after 72 h of fermentation, resulting in a productivity of 0.34 g/l h and in a bioconversion yield of 0.49 g/g.

Abstract: The present invention is directed to a regio- and stereoselective bioconversion of selected aliphatic dinitriles into corresponding cyanocarboxylic acids. More particularly, the present invention provides methods for the conversion of 2-isobutyl-succinonitrile into (S)-3 cyano-5-methylhexanoic acid, which is a useful intermediate in the synthesis of (S)-3(aminomethyl)-5-methylhexanoic acid (pregabalin). Pregabalin can be used for treating certain cerebral diseases, for example, in the treatment and prevention of seizure disorders, pain, and psychotic disorders.

Abstract: The hybrid anaerobic solid–liquid (HASL) system was a modified two-phase anaerobic digester developed for bioconversion of food waste. The aim of this study was to estimate the feasibility of the HASL system for the treatment of food waste with a high content of lipids. The presence of lipids in food waste increased the energy value of nutrients but could inhibit growth of methanogens. The positive effect of lipids on the performance of anaerobic digestion dominated when the contents of lipids were in the range from 20 to 30% of total solids of food waste. Lipid contents of 40% diminished the production of volatile fatty acids in the acidogenic reactor as well as biogas production and the concentration of total bacteria and methanogens in the methanogenic reactor. Therefore, the HASL system can be used for the treatment of lipid-containing food wastes if the lipid content is below 40% of total solids. Copyright © 2005 Society of Chemical Industry

Abstract: Xylose-to-xylitol bioconversion was performed utilizing Candida guilliermondii immobilized in sugarcane bagasse and cultured in Erlenmeyer flasks using sugarcane bagasse hydrolysate as the source of xylose Fermentations were carried out according to a factorial design, and the independent variables considered were treatment, average diameter, and amount of bagasse used as support for cell immobilization By increasing the amount of support, the xylitol yield decreased, whereas the biomass yield increased The diameter of the support did not influence xylitol production, and treatment of the bagasse with hexamethylene diamine prior to fermentation resulted in the highest amount of immobilized cells

Abstract: The present invention is directed to a substantially odorless biologically mediated treatment process for solid and liquid organic wastes. The present invention also provides for a novel nutrient rich humus material produced from the biologically mediated treatment process. The bioconversion process of the present invention results from low electron acceptor concentrations and high quantities of microorganisms in a diverse microbial community.

Abstract: Acidic metal-bearing wastewaters are treated to produce a finished water of sufficient purity to meet discharge standards while recovering metals removed in forms which are commercially valuable. The metals are selectively precipitated, either in a batch or in a continuous system, for removal of individual metal products in a specific sequence of steps from the wastewater. In each step, the pH is adjusted to the specific pH range and sulfide ion is introduced to precipitate the metals, excepting the removal of ferric iron and aluminum which is achieved using hydroxide precipitation. Bioconversion process using unique equipment converts sulfate in the wastewater to the hydrogen sulfide gas required for the precipitation process. This bioconversion process reduces the sulfate in the wastewater so that the water can be directly discharged or used for agricultural applications.

Abstract: Most of the freshwater systems in tropical countries are infested with one kind of aquatic weed or the other causing serious environmental problems. All efforts to control the growth and spread of these weeds have failed miserably and hence the concept of eradication through utilization is being adopted by many researchers. Solid state fermentation, the culturing of microorganisms on moist solid substrates in the absence or near absence of free water, has generated great deal of interest among researchers because of its various advantages over the submerged fermentation technique. Cellulase enzyme is used extensively in various industries, especially in textile, food and in the bioconversion of lignocellulosic wastes to alcohol. The extensive use of cellulase in industries depends on the cost of the enzyme and hence considerable research is being carried out to isolate better microbial strains and also to develop new fermentation processes with the aim to reduce the product cost. The objective of the present study is to determine whether water hyacinth, one of the commonly found aquatic weeds, can be used as a substrate for cellulase production, by three native bacterial isolates named WHB 3, WHB 4 and SMB 3, under the process of solid state fermentation. Results indicate that all the three isolates produced cellulase enzyme by using water hyacinth as the solid support. Under optimized conditions of moisture, pH, temperature, incubation time and inoculum concentration, the enzyme yield increased from 16.8 to 94.8 units for SMB 3, from 25.2 to 110.4 units for WHB 3 and from 18.0 to 127.2 units for WHB 4. The addition of nitrogen and carbon sources resulted in a significant increase in cellulase yield and WHB 3 produced the maximum amount of 216 units followed by SMB 3 and WHB 4.

Abstract: Modeling and simulation for simultaneous saccharification and fermentation (SSF) process in bioconversion of paper mill sludge to lactic acid was carried out. The SSF process combined the enzymatic hydrolysis of paper mill sludge into glucose and the fermentation of glucose into lactic acid in one reactor. A mathematical modeling for cellulose hydrolysis was developed, based on the proposed mechanism of cellulase adsorption deactivation. Another model for simple lactic acid fermentation was also made. A whole mathematical model for SSF was developed by combining the above two models for cellulose hydrolysis and lactic acid fermentation. The characteristics of the SSF process were investigated using the mathematical model.

Abstract: A laboratory-scale study of bioconversion of local lignocellulosic material, oil palm biomass (OPB) was conducted by evaluating the enzyme production through microbial treatment in solid state bioconversion (SSB). OPB in the form of empty fruit bunches (EFB) was used as a solid substrate and treated with the white-rot fungus, Phanerochaete chrysosporium, to produce ligninase. The results showed that the highest ligninase activity of 400.27 U/liter was obtained at day 12 of fermentation. While the optimum study indicated the enzyme production of 1472.8 U/liter with moisture content of 50%, 578.7 U/liter with 10% v/w of inoculum size, and 721.8 U/liter with co-substrate concentration of 1% (w/w) at days 9, 9 and 12 of fungal treatment, respectively. The parameters glucosamine and reducing sugar were observed to evaluate the growth and substrate utilization in the experiment.

Abstract: Biotransformation of methyl protodioscin (1) by Cunninghamella elegans (AS 3.1207) was investigated. Nine bioconversion products were isolated and identified. Eight of the bioconversion products were pregnane glycoside or steroidal saponins. It was found that steroidal saponin skeleton could be converted to pregnenolone skeleton only using microbial methods, which must have chemical procedures in the reported literatures. The found enriched the types of bioconversion reaction and provided a new way for the production of androstenedione. Most bioconversion products showed considerable cytotoxic activities against HepG2, NCI-H460, MCF-7 and HeLa cell lines compared to methyl protodioscin.

Abstract: Resumen en: Bioconversion of rice straw (Oriza sativa), coffee pulp (Coffea arabica) and banana leaves (Musa sapiensis) after Pleurotus ostreatus cultivation was ev...

Abstract: Compost produced by solid‐state bioconversion of the Indah Water Konsortium domestic wastewater treatment plant's sludge/biosolids significantly influenced the plant growth and development of corn (Zea mays). The solid‐state bioconversion refers to the control growth of microorganisms, generally on the surface of water‐insoluble substances for biodegradation of biopolymers and bioremediation of chemical compounds. Compost of biosolids with rice straw significantly increased plant height, shoot, and root dry weight. Moreover, it promoted 100.51% dry‐matter production compared to control. But the dry matter was recorded 46.80% only in urea (+N) application. The highest vegetative growth and delayed drying of basal leaves were attained using 1/2 of compost with 1/2 amount of urea, of the optimal dose of nitrogen (N) requirement for corn production. The recorded heavy metals concentration in plant tissues was quite low. Most of the heavy metals in composts of biosolids were on average 30 times lower ...