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BackgroundBioethanol obtained by fermenting cellulosic fraction of biomass holds promise for blending in petroleum. Cellulose hydrolysis yields glucose while hemicellulose hydrolysis predominantly yields xylose. Economic feasibility of bioethanol depends on complete utilization of biomass carbohydrates and an efficient co-fermenting organism is a prerequisite. While hexose fermentation capability of Saccharomyces cerevisiae is a boon, however, its inability to ferment pentose is a setback.ResultsTwo xylose fermenting Kodamaea ohmeri strains were isolated from Lagenaria siceraria flowers through enrichment on xylose. They showed 61% glucose fermentation efficiency in fortified medium. Medium engineering with 0.1% yeast extract and peptone, stimulated co-fermentation potential of both strains yielding maximum ethanol 0.25 g g−1 on mixed sugars with ~ 50% fermentation efficiency. Strains were tolerant to inhibitors like 5-hydroxymethyl furfural, furfural and acetic acid. Both K. ohmeri strains grew well on biologically pretreated rice straw hydrolysates and produced ethanol.ConclusionsThis is the first report of native Kodamaea sp. exhibiting notable mixed substrate utilization and ethanol fermentation. K. ohmeri strains showed relevant traits like utilizing and co-fermenting mixed sugars, exhibiting excellent growth, inhibitor tolerance, and ethanol production on rice straw hydrolysates.Electronic supplementary materialThe online version of this article (10.1186/s13065-018-0375-8) contains supplementary material, which is available to authorized users.

Upward flux of water and deep-placed (8-10 cm) P was studied in columns of sandyloam and silty clay loam, with water tables of 60 and 90 cm, each subjected to potential evaporation rates of 2-2 and 7-5 mm/day, for 15 days. An amount of 300 mg P/kg soil, labelled with 20 /tCi 32 P/g P, was applied as diammonium hydrogen orthophosphate.Evaporation losses increased with increase in potential evaporation (PE) and decrease in depth to water table in both soils, but the ratio of actual to potential evaporation (AE/PE) decreased with increasing PE, indicating that the evaporative losses in both the soils were mainly controlled by their hydraulic conductive properties. Under no circumstances did AE equal PE. Evaporation, in general, was higher from sandy loam than from silty clay loam.Corresponding to water flux, total upward P flux increased with increasing PE and decreasing depth to water. In the sandy loam, with 2-2 mm PE/day, 21 % of the deepplaced P moved to the soil surface with the 60 cm water table, against 5 % with the 90 cm water table. Under 7-5 mm PE/day, 39% P migrated to the surface with the 60 cm water table, but no 3a P was detected at the surface with the 90 cm water table.In the silty clay loam, however, P movement was much restricted.

α-amylase, an enzyme of industrial importance is used extensively in food, pharmaceutical, textile and detergent industries. Since, a substantial quantity of α-amylase isderived from microbial sources, manipulation of bacterial strain, fermentation conditions and media composition has a major effect on yield of enzyme. Bacillus amyloliqifaciens, obtained from MTCC culture collection was used to study the enhancement of α-amylase production using media concentration manipulation. Taguchi’s orthogonal array was designed for maximization of α-amylase output. The different media components selected as parameters to be optimized were calcium chloride, starch, tryptone, ammonium sulphate and glucose. The concentration of starch and tryptone demonstrated to have maximum effect on amylase production. The optimization strategy was successful in obtaining substantial increase in amylase production of about 2 folds as compared to the unoptimized medium.