Biosurfactant-producing Ability of Highly Efficient Petroleum-degrading Bacterium BS-8

After incubation for 6 -30 h, with the rapid increase of bacterial cell number, surface tension of bacterium BS-8 was reduced sharply from 63.2 mN/m to 39.4 mN/m. The production of biosurfactants by BS-8 was growth-dependent. Using glucose as the carbon source, bacterium BS-8 was incubated. Based on centrifugation, precipitation and chromogenie reaction of the culture solution, results indicated that the biosurfactants belonged to lipopeptides. The yield of biosurfaetants isolated and purified from the culture solution was 0.58 g/L, and the critical micelle concentration （CMC） was 90 mg,/L. Under conditions of pH 4 -9, tem- perature 20 -70 ℃, NaCl concentration 1% -6%, biosurfactants predueed by BS-8 exhibited the highest stability.

Screening of Feather Degrading Bacteria and Optimization of Fer-mentation Conditions from Poultry

The purpose of this experiment was to isolate and screen the microorganisms from the soil where chicken feathers were piled for a long time and identify them biologically.Single-factor test and response surface methodology(RSM)analyses were used to explore the optimum conditions for the growth and fermentation of a strain.Screening of bacterial strains from the soil where feathers were piled for a long time was performed,and 12 keratinolytic bacterial strains were isolated.One of these isolates,CH-7,was found to be the most effective feather-degrading strain,which was identified as Lactococcus lactis KU568489.1.The growth situation of feather keratin degrading bacterium analysis results showed that the best degradation effect of CH-7 was found in oxygen,inoculation 5%,initial pH=6.5,fermentation temperature 30℃,speed 220 r·min-1 and fermentation time 36 h,and CH-7 had the highest degradation rate of feather keratin.The optimization analysis of RSM showed that there was more significances of the three factors,32℃,pH 6.3 and amount of inoculum at 5.7%on the degradation of feather keratin.Based on the above results,the feather degrading bacterium,Lactococcus lactis CH-7,was obtained by screening,30℃and pH 5.5-6.5 were the best growth conditions.The oxygen,the amount of inoculum 5.7%,the fermentation temperature,32℃,pH 6.3 and the rotational speed 220 r·min-1 were the best fermentation conditions.Under these conditions,38.48%degradation rate was obtained after 36 h fermentation,which demonstrated the strain CH-7 was potential to the fermented feather meal for feed.

Two-step fermentation process and the corresponding study on its enzymology characteristics

Strain HIT-3,which has good performances in cellulose degradation,was isolated from the campus soil. Based on the identification of conservative sequences 16S rDNA and the analysis of physiological-biochemical characteristics,HIT-3 was identified as Achromobacter xylosoxidans. Denitrificans. A two-step fermentation process was conducted by adopting compound-bioflocculant-producing flora constructed by cellulose-degrading bacterium HIT-3 and flocculating bacterium F2. The cellulose degradation metabolites of HIT-3 was taken as substrates by flocculating bacterium F2,by which excellent compound bio-flocculant was obtained. In addition,the enzymology characteristics of HIT-3 were investigated when cultured in cellulose media,which utilized CMC-Na as its sole carbon. The results show that HIT-3 achieves a climax of 67.6 U/mL of enzyme production after incubation for 6 d,and the organic carbons produced are sufficient as the substrates required by the fermentation of flocculating bacterium F2(flocculating efficiency of 85.6%),which makes it feasible to reuse bioenergy.

Isolation andapplicationofanibuprofen-degrading bacterium toabiologicalaerated filter forthetreatmentof micro-polluted water

Ibuprofen(IBU)is widely used in the world as anti-inflammatory drug,which posed health risk to the environment.A bacterium capable of degrading IBU was isolated from activated sludge in a sewage treatment plant.According to its morphological,physiologic,and biochemical characteristics,as well as 16S rRNA sequence analysis,the strain was identified as Serratia marcescens BL1(BL1).Degradation of IBU required the presence of primary substrate.After a five-day cultivation with yeast powder at 30℃ and pH 7,the highest degradation(93.47%
2.37%)was achieved.The process of BL1 degrading IBU followed first-order reaction kinetics.The BL1 strain was applied to a small biological aerated filter(BAF)device to form a biofilm with activated sludge.IBU removal by the BAF was consistent with the results of static tests.The removal of IBU was 32.01% to 44.04% higher than for a BAF without BL1.The indigenous bacterial community was able to effectively remove CODMn(permanganate index)and ammonia nitrogen in the presence of BL1.