Screening Of Acid - Producing Strain And Analysis Of Acid - Producing Ability

Three ideal microbial strains, namely T10-3, DH-2-1 and 2-1 have been selected from the strains which were separated from Daqing crude oil, oil spills water and petroleum polluted soil. All that selected strains could grow under both aerobic and anaerobic conditions using petroleum as the sole carbon source. And they have the ability to produce organic acid in aerobic and anaerobic environments, the function of nitrate reductase and without hydrogen sulfide generation.After 14 hours separated fermentation of these three ideal strains, their fermentation samples were detected with HPLC (High performance Liquid Chromatography). For T10-3, its acetic acid, propanoic acid, and butyric acid were 1.10g/L,0.24g/L, and 1.57g/L respectively. In Dh-2-1, the acetic acid, propanoic acid and butyric acid were 2.37g/L,0.68g/L, and 2.21g/L respectively. And the propanoic acid of 2-1 was 0.51g/L.For 72-hour fermentation samples, their components were analyzed with the GC-MS (Gas Chromatography and Mass Spectrometry). The results showed that, for T10-3, the percentage of acetic acid, isobutyric acid and butanediol were 11.407%,9.375% and 79.217% respectively. The isobutyric acid, butanediol and isopentoic acid and enanthic acid of DH-2-1 were 41.563%,46.619% 4.138% and 10.680% respectively. In 2-1, there were 15.442% of isobutyric acid and 84.558% of butanediol.Bacterial indentification was undertaken by morphological, biological tests and 16SrDNA. The strains T10-3 and DH-2-1 belong to Bacillus subtilis and the strain 2-1 is Bacillus licheniformis.For toleration abilities analysis of different strains growing under different temperature, salinity and pH conditions, two strains as DH-2-1 and T10-3 were selected and analyzed. The results indicated that the optimal salinity was 3% for these two strains, the perfect temperature ranged from 40℃to 45℃, and the most appropriate pH...