Abstract: Continuous, steady-state fermentations using carbon monoxide gas as the sole carbon and energy source have been achieved with the CO strain ofButyribacterium methylotrophicum. Fermentation pH was found to regulate carbon monoxide metabolism over the pH range of 6.8 to 5.0. Cell growth diminished at low pH, with washout occurring at pH 5.0. As observed previously in batch culture, lower pH values favored production of butyrate over acetate. The mechanism responsible for this trend is currently being investigated by quantification of key intracellular enzyme activities. At low pH values, direct, steady-state fermentation of carbon monoxide to alcohols has been verified. Of major significance is the production of butanol from carbon monoxide in pure culture. This newly identified pathway provides a potential mechanism for direct bioconversion of synthesis gas to butanol.

Abstract: A hydantoin-hydrolyzing enzyme has been purified from an newly isolatedAgrobacterium sp. by procedures including ammonium sulfate fractionation and ion-exchange chromatography. Kinetic studies have demonstrated that this enzyme, which is strictlyd-selective and has a broad substrate specificity exhibits remarkable stability. Microbial bioconversion at 60°C and pH 10.0, allowed complete conversion of 30 g/L ofd,l 5-benzylhydantoin into thedN-carbamyl derivative of phenylalanine (molar yield of 96%) in less than 10 h. The hydantoinase is activated by Ni2+ ions.

Abstract: Various spent agro-residues obtained after cultivation of the edible mushroom Pleurotus sajor-caju were used in anaerobic digestors for production of biogas. The changes that take place in the residues during bioconversion were quantified in terms of composition of cellulose, hemicellulose, lignin, carbon and nitrogen. These “mycostraws” resulted in increased biogas production over the untreated ones, which varied from 21.5% in the case of spent bagasse to 38.8% in the case of spent paddy straw. The increased biogas generation by the spent residues seems to be due to the increased susceptibility to digestion and more favourable C/N ratio of the residues.

Abstract: Liquid cultures of a mutant strain of Fusarium sporotrichioides NRRL 3299 that accumulates trichodiene rather than T-2 toxin converted tricho-9-ene-2 alpha,3 alpha,11 alpha-triol, trichotriol (tricho-10-ene-2 alpha,3 alpha,9 alpha-triol), tricho-10-ene-2 alpha,3 alpha,9 beta-triol, 3 alpha-hydroxytrichothecene, and 3 alpha-acetoxytrichothecene to T-2 toxin. Other possible oxygenated precursors of T-2 toxin, including trichodiol (tricho-10-ene-2 alpha,9 alpha-diol), trichothecene, 4 alpha-hydroxytrichothecene, and 15-hydroxytrichothecene, were not metabolized. The results indicate that in the biosynthesis of T-2 toxin by F. sporotrichioides, (i) oxygenation at C-3 occurs prior to the second cyclization, (ii) this second cyclization involves two steps that may be nonenzymatic, and (iii) oxidation at C-3 precedes that at C-4 or C-15.

Abstract: Extraction of lactic acid from fermentation broths have been studied. The extractant selected for this research was paraffin oil which, in addition to having satisfactory physical properties, is non-toxic and does not affect the fermentability of the broth. Several amine compounds and a polymeric resin (Bonopore) have been tested to increase the extraction efficiency of the paraffin oil. Addition of these compounds gave higher K D values. However, all of the amine compounds tested are highly toxic to the free cells of L. delbrueckii (NRRL B-445). Bonopore, the polymer giving good absorption pattern and no deleterious effects was tested with paraffin oil in repeated batch culture of L. delbrueckii.

Abstract: Two biotechnological systems were developed for sucrose conversion into levan and ethanol withZymomonas mobilis, ensuring a 66.7% transfer of substrate carbon in a batch and 61% carbon transfer in a continuous culture. The effect of glucose, ethanol, and medium pH on sucrose conversion byZ. mobilis was studied. The addition of ethanol to the fermentation medium, in the final conc. of 100 g/L, uncoupled levan synthesis from ethanol fermentation. For a continuous culture, the most efficient conversion of substrate carbon into levan was reached at pH 4.8, giving 64.2 g/L levan, with the levan yield of 0.22 g/g and the productivity of 3.2 g/L/h.

Abstract: The application of the bioconversion process has been generally restricted to the production of fine chemicals that are difficult to obtain through conventional chemical methods. Recently, however, the industrial production of acrylamide, an important commodity chemical, using bacterial nitrile hydratase, was started in Japan. We describe here the first successful example, the enzymatic production of acrylamide, and the recent progress in the microbial transformation of nitriles. The cofactors and reaction mechanism of nitrile hydratase are also discussed.

Abstract: The transformation of hydrogen sulfide into elementary sulfur and sulfate was investigated in a photo-bioreactor using autotropic bacteriaChlorobiumthiosulfatophilum. The accumulations of sulfur and sulfate in the reactor were found to be dependent on the light energy and the feed rate of H2S. The optimum operation lines were established to limit sulfide or sulfate. Immobilization of the whole cells in strontium-alginate matrix enhanced the conversion more than with the free cells.

Abstract: The anaerobic bioconversion of selected phthalic acid esters (PAEs) was investigated using inocula from diverse natural habitats. Results of bioconversion studies indicated that di‐n‐butyl phthalate (DBP) and butyl benzyl phthalate (BBP) levels were reduced by 80% and 50%, respectively, after 4 weeks incubation in samples inoculated with diluted anaerobic digester sludge; greater than 90% bioconversion of DBP and BBP was observed in samples inoculated with either anaerobic freshwater or salt marsh sediment. Bis(2‐ethylhexyl) phthalate (DEHP) was not degraded by any inocula tested. The persistence of DEHP was apparently not associated with DEHP toxicity to indigenous microflora.

Abstract: Inactivation of the alcohol oxidase enzyme system of Pichia pastoris, during the whole-cell bioconversion of ethanol to acetaldehyde, was due to catabolite inactivation. Electron microscopy showed that methanol-grown cells contained peroxisomes but were devoid of these microbodies after the bioconversion. Acetaldehyde in the presence of O2 was the effector of catabolite inactivation. The process was initiated by the appearance of free acetaldehyde, and was characterized by an increase in the level of cyclic AMP, that coincided with a rapid 55% drop in alcohol oxidase activity. Further enzyme inactivation, believed to be due to proteolytic degradation, then proceeded at a constant but slower rate and was complete 21 h after acetaldehyde appearance. The rate of catabolite inactivation was dependent on acetaldehyde concentration up to 0.14 mM. It was temperature dependent and occurred within 24 h at 37°C and by 6 days at 15°C but not at 3°C. Alcohol oxidase activity was psychrotolerant, with only a 17% decrease in initial specific activity over a temperature drop from 37 to 3°C. In contrast, protease activity was inhibited at temperatures below 15°C. When the bioconversion was run at 3°C, catabolite inactivation was prevented. In the presence of 3 M Tris hydrochloride buffer, 123 g of acetaldehyde per liter was produced at 3°C, compared with 58 g/liter at 30°C. By using 0.5 M Tris in a cyclic-batch procedure, 140.6 g of acetaldehyde was produced.

Abstract: Pseudomonas sp strains, isolated from soil, utilized toluene as their sole carbon source through ameta cleavage pathway Strains metabolizing toluene through anortho cleavage pathway were selected from the wild typemeta strain Theortho pathway strains were subjected to chemostat selection to obtain a fast-growing strain with doubling time reduced from 14 to 12 h Benzoale and antibiotics enrichment selection procedures were utilized to select a blocked mutant The blocked mutant grew on acetate as its sole carbon source and oxidatively converted toluene tocis, cis-muconic acid Double-blocked and muconate-permeable mutants were also selected to reduce reversion frequency and to enhance muconic acid production In shake-flask experiments, muconic acid at 35 g/l was obtained after 2 days of fermentation In a 14 l fermenter, muconic acid was produced at 45 g/l in 4 days of controlled fed-batch fermentation The oxidative bioconversion process was also demonstrated in a 1500 l fermenter

Abstract: Proliferation of macroalgae is a world-wide problem with 50,000 m3 of drift Ulva harvested per year in Brittany and about 1.0 to 1.2 million tons growing in the Venice lagoon. This biomass may be treated by bioconversion (aerobic or anaerobic fermentation) to give useful products (gas, fertilizers or others) and to remove a source of environmental pollution. Such a treatment also may be applied to cultivated or harvested seaweeds and to seaweed industry residues.

Abstract: The transformation of hydrocortisone to prednisolone was studied in aqueous two-phase systems, as a model for the extractive bioconversion of fine chemicals. The bacterium, Arthrobacter simplex, was able to grow in the two-phase system and the cells could be revitalized after a period of use. Use of aqueous two-phase systems made it possible to operate the reaction at higher substrate concentrations than in pure buffer solution. An adsorptive method to remove the product from the top phase was tested and shown to be both efficient and compatible with the overall process. In order to reduce the costs of operation in aqueous two-phase systems, a cheaper starch-based polymer, Reppal-PES, was successfully used as a substitute for dextran.

Abstract: The ability of the monensin-producing organism Streptomyces cinnamonensis to bioconvert the (E)-and (Z)-isomers of nerolidol (= 3,7,1 1-trimethyldodeca-1,6,10-trien-3-ol) into new oxygenated products has been investigated. When a 3H-labelled racemic form of each sesquiterpene was added to fermentations of S. cinnamonensis, several new 3H-labelled products could be detected. Two products were isolated from bioconversion of (E)-nerolidol, the amide 8 and the 9 (Scheme 2), whereas four products were isolated from the bioconversion of (Z)-nerolidol, the epoxydiol 10, triols 11 and 12, and the tetrahydrofuryl alcohol 13 (Scheme 4). Products 9–13 were obtained as a 1 : 1 mixture of diastereoisomers, and 12 was shown to arise by the overall anti addition of two OH groups to the trisubstituted (Z)-double bond of (Z)-nerolidol. Both isomers of nerolidol as well as the acetylene 7 are inhibitors of monensin production in shake cultures of S. cinnamonensis.

Abstract: A bioconversion process with Aspergillus parasiticus has been developed to enhance p-hydroxylation activities with respect to aromatic substrates such as m-terphenyl. Through modified growth conditions, we are improving product concentration, while streamlining fermentation and downstream processing requirements. We routinely carry out biosynthetic conversions with m-terphenyl at the 300-L scale and produce over 200 g of 4,4″-dihydroxy-m-terphenyl at a concentration of 0.7 g/L in the fermentation vessel.

Abstract: The bioconversion of avermectin to its 27-hydroxy derivative is achieved withNocardia autotrophica subsp.canberrica. The approach of increasing bioconversion productivity rather than efficiency was adopted in these studies. Process improvement studies focused on the physico-chemical conditions of the fermentation, examined initially at the shake-flask scale. Bioconversion yields were affected by pH, substrate concentration, time of substrate addition, substrate solubilization, carbon to nitrogen ratio, and medium strength. Optimization of these parameters resulted in a 8-fold process improvement. During pre scale-up studies, the sensitivity of this bioconversion to the antifoam employed was demonstrated and lard oil was selected as giving the best results. Additional process changes were required during scale-up efforts in larger vessels, including replacement of the original substrate solvent with dimethylsulfoxide.

Abstract: Using residue biomass as feedstock for conversion to calcium magnesium acetate (CMA) as an alternative road salt has been investigated. This salt is less corrosive to bridge decks and vehicles than sodium chloride, the traditional road salt. CMA derived from residue biomass is expected to be less costly than that derived from petroleum or natural gas. The residue biomass may be woody biomass residues not suitable for lumber or paper pulp, industrial residues such as whey, municipal solid waste (MSW), or sewage sludge. This study focused on bioconversion of sewage sludge to CMA based on “suppressed methane” fermentation to produce acetic acid followed by liquid ion exchange to recover acetic acid from the fermenter broth prior to reaction with limestone. Overall feasibility was evaluated using results from laboratory work and cost estimates from a preliminary engineering process model. Percent bioconversion and kinetics to acetic acid were confirmed in small batch fermenters. Equilibrium constants for acetic acid recovery via liquid ion exchange were measured. Rates of conversion to CMA were determined.

Abstract: Whole cells of methylotrophic yeasts are able to oxidize benzyl alcohol to benzaldehyde in aqueous reaction media. However, the low water solubility of the reactant and product of this bioconversion, combined with the ability of both to strongly inhibit the reaction, suggested to us the use of non-aqueous reaction fluids. Using non-aqueous systems, it was found that Pichia pastoris can be used to oxidize higher alcohols. The alcohol oxidase from such yeast had been previously reported unable to oxidize such alcohols. Purified alcohol oxidase was shown to function in a number of two-phase systems of varied aqueous to organic phase concentrations. The stability and biocatalyst recovery of the enzyme was improved by immobilization.

Abstract: Alginate-entrapped cells of Mucuna pruriens as well as the phenoloxidase isolated from the cell cultures, are able to ortho-hydroxylate several mono-, bi- and tri-cyclic monophenols. In this study, 7,8-dihydroxy N-di-n-propyl 2-aminotetralin, a catechol of pharmaceutical interest and difficult to prepare chemically, could be produced in considerable quantities by bioconversion of the precursor 7-hydroxy N-di-n-propyl 2-aminotetralin. A continuous flow system on a laboratory scale was used, which consisted of a phenoloxidase suspension in dialysis tubing as the biocatalysator in an airlift fermentor coupled with an aluminium oxide column for selective product isolation. Product formation continued for at least 50 h, resulting in ca. 130 mg product per liter, this being a bioconversion percentage of 25%. When the enzyme preparation was reused, 85% of the original activity was measured.

Abstract: The conversion of 2,6-dialky naphthalene to the corresponding 2,9-dicarboxy naphthalene by microbiological means is described. Exemplary means include the use of NAH7 plasmids, encoding aromatic oxygenase enzymes, in a Pseudomonas host. The conversion product is useful as a monomer in the production of high performance synthetic polymers.