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This study details the indigenous oil-degrading consortia, using crude oil as sole carbon and energy sources, which were screened out from the oily sludge of Central-Asia arid region via a crude oil mineral salt medium (MSM) plate tests. The enriched consortia are considered as heterotrophic alkali- tolerant microorganisms, which readily grew under the pH 6.0-12.0. Moreover, petroleum hydrocarbon degradation in water exhibited that the decomposition rate was the highest at pH 11.0 and reached 68.57% for the 8 d period. For the alkaline oily sludge with pH of ~10, the selected consortia could consume 60% of petroleum hydrocarbon in 7 days of aerobic cultivation, indicating that it had the potential practical application in remediation of crude oil-contaminated saline-alkaline soil and sludge. GC-MS analysis of the residual hydrocarbons showed that chain saturated alkane (C8 to C20) was greater than 90% treated for 8 days. Based on 16S rRNA gene sequences, the consortia were identified as Porphyrobactercryptus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. Overall, the obtained oil-degrading strain presented a short growth period, the ease of isolation and screening, as well as the high crude oil degradation capacity and alkali-tolerant property, which would endow it to degrade crude-oil under alkali-wastewater or sludge. [ABSTRACT FROM AUTHOR]

The over-expression of exogenous proteins in Escherichia coli usually led to forming insoluble proteins due to misfolding or aggregation. Molecular chaperones might ameliorate this problem for some specific proteins. In order to improve the production of soluble human-like collagen (HLC), the roles of different chaperone teams on HLC were investigated. The GroEL team could increase the production of soluble HLC by assisting the correct folding of HLC and increasing the mRNA level of the gene coding for HLC. Trigger factor (TF) also played a positive role in HLC expression; whereas, the extent of the increase of soluble HLC production depended on the expression level of TF. Moreover, the DnaK team did not work positively on soluble HLC, which might result from the unbalanced ratio of DnaK:DnaJ:GrpE. Compared with the parent strain without the transformation of any chaperone plasmid, the production of soluble HLC with overexpression of the GroEL team from the starting point of cultivation was increased by 32.4%. [ABSTRACT FROM AUTHOR]

In order to reduce the production cost of human-like collagen (HLC), a minimal medium was introduced. On the base of Design of experiments (DOE), especially Plackett-Burman design and central composite design, a modified minimal medium that could give a high yield of HLC was developed. The optimum minimal medium for engineered E. coli BL21 ΔptsG contained 6.11g/L of glucose, 5.82g/L of (NH4) 2SO4, 1.80x10-4gL of thiamine and 3.00x10-2L of trace element solution, the other ingredients were same to that in M9 medium. And the HLC production of ptsG mutant reached to 0.26g/L in this optimized minimal medium, which approached to 0.27g/L produced by the strain without deleting ptsG gene in an optimized complex medium. [ABSTRACT FROM AUTHOR]