The dibenzothiophene (DBT) desulfurization pathway of a facultative thermophilic bacterium Mycobacterium sp. X7B was investigated. Metabolites were identified by gas chromatography-mass spectrometry, and the results showed that 2-hydroxybiphenyl, the end product of the previously reported sulfur-specific pathway (also called 4S pathway), was further converted to 2-methoxybiphenyl. This is the first strain to possess this ability and therefore, an extended 4S pathway was determined. In addition, the DBT-desulfurizing bacterium Mycobacterium sp. X7B was able to grow on DBT derivatives such as 4-methylDBT and 4,6-dimethylDBT. Resting cells could desulfurize diesel oil (total sulfur, 535 ppm) after hydrodesulfurization. GCflame ionization detection and GCatomic emission detection analyses were used to qualitatively evaluate the effect of Mycobacterium sp. X7B treatment on the content of the diesel oil. The total sulfur content of the diesel oil was reduced 86% using resting cell biocatalysts for 24h at 45℃.

On an industrial scale, the production of pyruvate at a high concentration from the cheaper lactate substrate is a valuable process. To produce pyruvate from lactate by whole cells, various lactate-utilizing microorganisms were isolated from soil samples. Among them, strain WLIS, identified as Acinetobacter sp., was screened as a pyruvate producer. For the pyruvate preparation from lactate, the preparative conditions were optimized with whole cells of the strain. The cells cultivated in the medium containing 100mM of L-lactate showed the highest biotransformation efficiency from lactate to pyruvate. The optimized dry-cell concentration, pH, and temperature of reaction were 6g/L, pH 7.0-7.5, and 30℃, respectively. The influences of ethylenediaminetetraacetic acid (EDTA) and aeration on a biotransformation reaction were carried out under the test conditions. Under the optimized reaction conditions, L-lactate at concentrations of 200 and 500mM were almost totally stoichiometrically converted into pyruvate in 8 and 12h, respectively. About 60% of 800mM of L-lactate was transformed into pyruvate in 24h. This reduced conversion rate is probably due to the high substrate inhibition in biotransformation.

Biodegradation of carbazole was enhanced by the presence of a non-aqueous phase liquid (logKo/w≥3.1) at phase ratio of 1:1 (organic/aqueous). In a cyclohexane/aqueous phase system, the maximum specific degradation rate (3.34mg carbazole min−1g dry cell−1) was at an organic/aqueous ratio of 1:1. Pseudomonas sp. XLDN4-9 degraded 47% (w/w) of 1g carbazole l−1 in cyclohexane phase directly within 1h.

Ethanol concentration and fermentation productivity using Saccharomyces cerevisiae were substantially increased in shake flask cultures with a normal inoculum by combining 3 methods: (a) by making nutrient additions to the standard medium for ethanol production, (b) by immobilizing the cells in alginate beads and (c) by using a glucose step-feeding batch process. Ethanol concentration by free yeast was improved from 5.9% (w/w) to 9.6% (w/w) when a further 0.8% yeast extract and 1% animal peptone were added to the standard 30% (w/v) glucose nutrient medium. This was further increased to 12.8% (w/w) by using alginate immobilized yeast. The ethanol concentration was increased again, to 15.0% (w/w) by using the glucose step-feeding batch process.