Abstract: The use of biphasic systems consisting of water and a water-immiscible organic solvent offers a number of advantages for the bioconversion of water-insoluble reactants. Hydrolytic enzymes can also be used in such systems to synthesize peptide and ester bonds.

Abstract: The biomass resource thermochemical conversions bioconversion bio-energy and development environmental factors.

Abstract: The activities of populations in complex anaerobic microbial communities that perform complete bioconversion of organic matter to CH4 and CO2 are reviewed. Species of eubacteria produce acetate, H2, and CO2 from organic substrates, and methanogenic species of archaebacteria transform the acetate, H2, and CO2 to CH4. The characteristics and activities of the methanogenic bacteria are described. The impact of the use of H2 by methanogens on the fermentations that produce acetate, H2, and CO2 and the importance of syntrophy in complete bioconversion are discussed.

Abstract: Aspergillus awamori and Trichoderma reesei were used, separately and in mixed culture, to convert apple distillery waste into microbial biomass. Overall, the use of mixed culture had considerable advantages, the positive properties of each species being retained. The effect of Aspergillus is evident in improved filtration and chemical oxygen demand reduction, as well as in the β-glucosidase synthesis. Trichoderma, on the other hand, contributes to good fibre degradation, protein enrichment of the biomass and cellulolytic, xylanolytic and pectolytic activities in the filtrates.

Abstract: Production of l-phenylalanine from trans-cinnamic acid using isolate SPA10 cells was reduced to 26% of that observed initially when cells were reacted a second time with fresh substrate mixture. The stability (reuseability) of Phenylalanine Ammonia-Lyase (PAL) containing cells was significantly influenced by both the trans-cinnamate concentration and initial reaction pH. Using 2% t-cinnamate, l-phenylalanine production was 7-fold greater after 3 successive runs at pH 9.0 than at the optimum of pH 10.2. Cells reacted in the presence of 5% t-cinnamate were relatively unstable. Permeabilising agents, such as toluene and xylene, stimulated l-phenylalanine production but also enhanced instability of the catalyst. Several effectors were shown to stimulate the initial rate of the PAL bioconversion, but only sorbitol, alginate, glutaraldehyde, polyethylene glycol and glycerol conferred any significant degree of stability. Sparging of cultures and bioreactors with various gases revealed that oxygen enhanced PAL inactivation, CO2 had little effect and nitrogen conferred remarkable stability on PAL activity for several weeks in culture medium. The presence of chloride ions (from HCl) and aeration of substrate mixtures resulted in poor reuseability of catalyst. A combination of H2SO4 substitution for HCl and N2-sparging resulted in excellent initial conversions and good catalyst stability at 26°C but less at 30°C. The inclusion of 1.5 M sorbitol in reaction mixtures maintained PAL stability over several successive incubations.

Abstract: Bioconversion of citronellol 1 was studied with four strains of Botrytis cinerea. Using grape must predominant transformation of 1 to 2,6-dimethyl-1,8-octandiol 2 and (E)-2,6-dimethyl-2-octen-1,8-diol 3 was observed. In minor amounts 2,6-dimethyl-2,8-octandiol 4, two p-menthan-3,8-diol isomers 5a, 5b, (Z)-2,6-dimethyl-2-octen-1,8-diol 6, isopulegol 7, 2-methyl-2-hepten-6-one-1-ol 8 and 2-methyl-γ-butyrolactone 9 were found. Using a small amount of grape must in a synthetic medium (1:700) the bioconversion products 2, 4, 5a and 5b were absent, but additionally 2-methyl-2-hepten-6-one 10, 2-methyl-2-hepten-6-ol 11 and citronellic acid 12 were detected. The results obtained were strongly dependent on the strains used; one strain did not show any metabolic activity against 1. The bioconversion products were identified by capillary gas chromatography (HRGC) and coupled HRGC techniques, i.e. on-line — mass spectrometry (HRGC-MS) and — Fourier transform infrared spectroscopy (HRGC-FTIR).

Abstract: Among the problems associated with the bioconversion of monoterpenes by plant cell suspensions are the toxicity of some substrates and/or products at low concentrations, the transient state of nascent products and the length of time required to obtain the cell suspension. We investigated the extractive bioconversion of geraniol by a Vitis vinifera c.v. Muscat de Frontignan cell suspension in a two-phase system consisting of an aqueous nutrient phase surmounted by a lipid (Miglyol 812) phase. This system proved to be advantageous as it allowed a five-fold increase in the substrate load without causing any detrimental effect on the cell suspension, it improved the persistence of nascent products and it permitted the recycling or re-use of the cell suspension in a monoterpene bioconversion process.

Abstract: In this investigation the bioconversion of glycerol from glucose was studied in a laboratory fermentor using an alkaline medium with a fed batch mode of carbon source addition yielding 30% glycerol concentration in the final broth. (Refs. 9).

Abstract: A novel two-stage bioreactor has been designed for a combined submerged (SF) and solid substrate fermentation (SSF) of wheat straw. The straw was pretreated with steam, and cellulases from the culture fluid of Trichoderma reesei were adsorbed on it for increased bioconvertibility. SSF was conducted in the top part of the bioreactor by inoculating the straw with a 36-h mycelial culture of T. reesei, or Coriolus versicolor. In the bottom part of the fermenter, Endomycopsis fibuliger was grown in SF. The SF liquor was recirculated through the SSF stage at 24 h intervals to remove glucose and other metabolites that may inhibit growth, and to maintain optimum moisture level and temperature. The removed glucose and other metabolites provided nutrients for the yeast in the SF stage. The combined fermentation resulted in overall higher biomass yield, increased bioconversion, increased cellulase production, and increased digestibility compared with single SSF or SF.

Abstract: The use of sodium sulphite as a steering agent for enhancing the yield of glycerol during anaerobic ethanol fermentation is well established. Several studies have been reported in the literature using free as well as immobilized cells of Saccharomyces cerevisiae. In these studies it was observed that a relatively high concentration of sulphite in the fermentation broth, typically 40-100 g/l, was required to obtain a commercially significant yield of glycerol on sugar fermented. However, the dosing of large quantities of sulphite generally resulted in reduced viability of the microorganisms and slow fermentations. The glycerol concentration in the fermented broth was generally observed to be in the range 20-40 g/l. The low productivity coupled with the high cost of sulfite rendered the process commercially unattractive. In order to reduce the sulphite requirement, whilst at the same time increasing the productivity, a modified vacuum fermentation was developed in the laboratories. The process was successfully estabilished on a pilot scale and typical data obtained on scaleup are reported below. 8 references.

Abstract: The solid-substrate fermentation of wheat straw with an alkaliphilic white-rot fungus (Coprinus sp.) was found to be influenced by the levels of nitrogen, phosphorus+sulphur and free carbohydrates, in terms of biodegradation of straw ingredients, microbial protein production and changes in in-vitro dry matter digestibility (IVDMD). Nitrogen and Phosphorus+Sulphur compounds favoured the bioconversion and their optimum levels were (g/100 g DM): urea (sterile): 1.5, urea (unsterile): 3.0; superphosphate: 1.0. The addition of free carbohydrates as molasses and whey had detrimental effect on biodegradation of lignin as also on organic matter degradation and digestibility. However, the protein production was enhanced in the supplemented straw. The optimized laboratory fermentation was also extended to 4 kg-(sterile and unsterile) and 50 kg-(unsterile) fermentation.

Abstract: None of the fourteen thermophilic moulds was able to break down the aliphatic side chain of sterols,viz. cholesterol, lanosterol, sitosterol, and stigmasterol so as to yield 4-androstene-3, 17-dione, 1,4-androstadiene-3, 17-dione and progesterone. InAcremonium alabamensis and.Talaromyces emersonii, cholestenone was detected as a product of fermentation of cholesterol whereas the former yielded stigmastadienone from stigmasterol and sitosterol. Lanosterol appeared to be resistant to fungal bioconversion. All the thermophilic moulds exhibited avidity for binding sterols to the mycelium, but the ability to bind sterol seemed to depend upon the nature of the organism and the sterol.

Abstract: A solid state fermentation process was developed for the conversion of straw and cellulose under anaerobic conditions by a mixed culture of cellulolytic and methanogenic organisms. The bioconversion rate and efficiency were compared under mesophilic (35° C) and thermophilic (55° C) conditions. Cellulolytic activity was assayed in terms of sugar and overall soluble organic matter (chemical oxygen demand, COD) production. Maximum conversion rates were obtained under thermophilic conditions, i.e. 8.4 g and 14.2 g COD/kg·d, respectively, when wheat straw and cellulose were used as substrates. The cellulolytic activity of the reactor contents (23% dry matter), measured under substrate excess conditions, amounted to 50 g COD/kg·d. As a comparison, the activity of rumen contents (15% dry matter) measured by the same assay amounted to 150 g COD/kg·d. The anaerobic cellulases appeared to be substrate bound. This and the relative low activity levels attained, limit the perspectives of producing cellulase enzymes by this type of process.

Abstract: The authors designed and tested a new process for converting fodder beets to ethanol: continuous diffusion-fermentation. This process utilizes the simultaneous diffusion-fermentation concept of the EX-FERM design; however, it overcomes the material handling problems inherent in that system by utilizing a counterflow tubular auger system. This process also eliminates the need for roller mills or presses and dryers which are required for alcohol recovery from solid phase fermentation. The latter is the only other currently feasible procedure for producing distillably worthwhile amounts of ethanol from fodder beets, sweet sorghum, and other similar feedstocks. Results on the use of sodium meta bisulfite (SMB) for contamination control with fermenting fodder beet cubes are reported.

Abstract: Two basidiomycetes cultures, BH1 and BW1, isolated from the biomanure sample of a bio-gas plant belonging to Polyporus sp., were used in combination with celluolytic cultures viz. Trichoderma sp. and Cellulomonas strain R2 for microbial protein production from whole bagasse. The biomass yields obtained were much higher in mixed cultures fermentation than in corresponding controls. Combination of BH1/BW1 with Cellulomonas proved to be the better in comparison with Trichoderma. Simultaneous inoculation of the bacteria along with BH1 culture resulted in higher protein production.

Abstract: The utilization of cellulose from one ton of lignocellulose for ethanol production would yield 150–250 kg of hemicelluloses. The total soluble solids in the hemicellulose fraction (HF) obtained with the Universite de Sherbrooke (UdeS) process contained about 56% carbohydrates. These carbohydrates were present in the form of oligomers of various sugars, predominantly xylose. All the test fungi,Chaetomium cellulolyticum, C. cellulolyticum (asporogenous mutant) andPleurotus sajor-caju, were capable of utilizing all the carbohydrates present in HF.C. cellulolyticum gave the highest amount of protein (7 g/l) from 19 g carbohydrates/l. The yield of protein was higher than expected, indicating that carbon compounds other than reducing sugars present in HF might have been consumed for fungal growth. The inhibitory effect of toxic compounds on protein production increased with an increase in concentration of soluble solids in HF. The inhibitory effect was overcome by increasing the pH of the medium to 6.0 or 7.0. Fungal protein production from hemicelluloses will give extra revenue in our integrated approach for ethanol production from lignocelluloses.

Abstract: The utilization of the cellulose and hemicellulose of pretreated biomass for the production of fuels and chemicals was investigated. Aspenwood was pretreated by steam-explosion and then fractionated by water-extraction into a water-extract fraction rich in sugars from hemicellulose and a cellulose-rich residue. The two fractions were then hydrolyzed either by acid or fungal enzymes (cellulase and xylanase enzyme complexes of Trichoderma harzianum E58) to component sugars. The sugar mixtures of both the acid and enzyme hydrolyzates of the cellulose or hemicellulose fractions could be fermented efficiently by Klebsiella pneumoniae ATCC 8724 and Clostridium acetobutylicum ATCC 824 for the production of butanediol and butanol, respectively. The production of butanediol was further enhanced by combining enzymatic hydrolysis and fermentation (CHF). The process was readily scaled up in laboratory fermentors. The process was also successfully extended to the utilization of the combined cellulose and hemicellulose components of aspenwood and agricultural residues (i.e., steam-exploded biomass without further extraction). The results demonstrated the industrial potential of the two organisms for the bioconversion of total biomass carbohydrates to valuable fuels and chemicals.

Abstract: Large quantities of cull bananas are available world-wide, and often in regions lacking indigenous sources of high-quality protein animal feedstuffs. One possible method of utilizing these wastes is to upgrade them to microbial protein by means of bioconversion of the fermentable sugars of the ripe or over-ripe pulp by the yeastCandida utilis, which is nutritionally well-accepted. Studies of ripeMusa sapientum var. ‘Gros Michel’ bananas were conducted in order to obtain both the microbial and the engineering data necessary for the development of such an aerobic fermentation process. For banana pulp fermentation liquors in the concentration range 10 to 35% (w/v) fresh weight (FW) banana, the corresponding dry weight banana concentrations and the fraction of insoluble solids before and after sterilization (121°C, 30 min) have been measured and are reported. In addition to fermentation studies of banana liquor prepared from 10% (w/v) fresh whole banana, comparative kinetic studies of the batch growth and substrate assimilation pattern were performed on media containing as the sole soluble carbohydrate source either one of the major banana sugars (glucose, fructose, sucrose) or a mixture of the three. Wherever feasible, the maximum specific growth rate (μmax) was evaluated by four different methods: dry weight biomass, optical density, crude protein content of broth insoluble solids and dissolved oxygen history. In addition to the comparative μmax results, values of the biomass yield coefficient and the specific respiration rates for each case are presented and discussed. A preliminary process design of the fermentation section of a moderate-scale microbial protein production plant based on 20,000 kg FW banana/day feedstock is presented. The results of this study indicate that such a plant would yield about 2,900 kg/day of protein-enriched product containing 5 wt% moisture and 44 wt% (c. 1,400 kg/day) crude protein.

Abstract: The polyhydric alcohols, glycerol and sorbitol, significantly increased the rate ofl-phenylalanine production from trans-cinnamic acid using whole cells ofRhodotorula rubra. Chloride ions and oxygen prevented the stimulatory effect of the polyhydric alcohols. Furthermore, the severe inhibition, of the biotransformation by high trans-cinnamic acid concentrations was alleviated in the presence of glycerol, and sorbitol. The rate of conversion could be manipulated still further, even with high trnas-cinnamic acid concentrations, by elevating the reaction pH to, 12 in the presence of polyhydric alcohol. When cells were also treated first with glutaradehyde (0.1% v/v) and then polyethylene glycol (15% v/v), although neither compound stimulated the actual rate of bioconversion, the reaction was markedly stabilised and gave a 73% yield after 28 days of continuous operation.

Abstract: The invention relates to a process of selective bioconversion of DINIS into MONIS-5, wherein the DINIS is added to a medium containing at least one microorganism possessing a glutathion transferase or an acellular extract of such a microorganism.