Application and comparison in biosynthesis and biodegradation by Fusarium solani and Aspergillus fumigatus cutinases.

In this study, two synthesized cutinase genes from Fusarium solani and Aspergillus fumigatus were expressed in Pichia pastoris X33. The characteristics of these two cutinases were investigated and compared. The results indicated that F. solani and A. fumigatus cutinases hydrolyzed p-nitrophenyl substrates with different carbon chain lengths. A. fumigatus cutinase predominately hydrolyzed p-nitrophenyl butyrate, but F. solani cutinase preferred p-nitrophenyl decanoate. The abilities of polymer synthesis and bioplastic degradation were tested and compared between F. solani and A. fumigatus cutinases. The results showed that F. solani cutinase had degradation ability on poly(ε-caprolactone) (PCL) and synthesized polymer with a molecular weight (MW) of 2300 in organic solvent. However, A. fumigatus cutinase completely degraded PCL and synthesized molecules with a MW of 25,000, suggesting that A. fumigatus cutinase has more promising applications.

Further characterization of o-nitrobenzaldehyde degrading bacterium Pseudomonas sp: ONBA-17 and deduction on its metabolic pathway

A previously reported o-nitrobenzaldehyde (ONBA) degrading bacterium Pseudomonas sp. ONBA-17 was further identified and characterized. Based on results of DNA base composition and DNA-DNA hybridization, the strain was identified as P. putida. Its degradation effect enhanced with increase of inoculum amount and no lag phase was observed. Higher removal rate was achieved under shaking conditions. All tested ONBA with different initial concentrations could be completely degraded within 5 d. In addition, degradative enzyme(s) involved was confirmed as intra-cellular distributed and constitutively expressed. Effects of different compounds on relative activity of degradative enzyme(s) within cell-free extract were also evaluated. Finally, 2-nitrobenzoic acid and 2, 3-dihydroxybenzoic acid were detected as metabolites of ONBA degradation by P. putida ONBA-17, and relevant metabolic pathway was preliminary proposed. This study might help with future research in better understanding of nitroaromatics biodegradation.

Further characterization of o-nitrobenzaldehyde degrading bacterium Pseudomonas sp. ONBA-17 and deduction on its metabolic pathway.

A previously reported o-nitrobenzaldehyde (ONBA) degrading bacterium Pseudomonas sp. ONBA-17 was further identified and characterized. Based on results of DNA base composition and DNA-DNA hybridization, the strain was identified as P. putida. Its degradation effect enhanced with increase of inoculum amount and no lag phase was observed. Higher removal rate was achieved under shaking conditions. All tested ONBA with different initial concentrations could be completely degraded within 5 d. In addition, degradative enzyme(s) involved was confirmed as intra-cellular distributed and constitutively expressed. Effects of different compounds on relative activity of degradative enzyme(s) within cell-free extract were also evaluated. Finally, 2-nitrobenzoic acid and 2, 3-dihydroxybenzoic acid were detected as metabolites of ONBA degradation by P. putida ONBA-17, and relevant metabolic pathway was preliminary proposed. This study might help with future research in better understanding of nitroaromatics biodegradation.

[Screening, denitrification characteristics, and anaerobic ammonium oxidation ability of denitrifying bacterium aHD7].

A highly efficient denitrifying bacterium aHD7 was screened from activated sludge. After static culture at 30 degrees C for 3 days, the denitrification rate of the aHD7 reached 91.7%, and during denitrification, nitrite had lower accumulation, with its concentration basically maintained at 1.8 mg x L(-1). The microscopy observation demonstrated that the aHD7 was a gram-negative bacillus, with an average size of 0.5 microm x (1.5-2.5) microm. Based on its biochemical/morphological characteristics and homologic analysis of 16S rDNA sequence, the aHD7 was identified as Pseudomonas mendocina. The investigation on the factors affecting the denitrification capacity of aHD7 showed that at the initial concentration of nitrate nitrogen being less than 276.95 mg x L(-1), the denitrification rate was almost 100%, and when the initial concentration of nitrate nitrogen was as high as 553.59 mg x L(-1), the denitrification rate could reach 66.8%, with little nitrite accumulated. Ethanol was the most suitable carbon source. C/N ratio 6-8 and pH value 6-9 benefited the denitrification. The aHD7 had a good ability of anaerobic ammonium oxidation, and its average ammonium utilization rate reached 4.56 mg x L(-1) x d(-1).

[Mechanism of trichosanthin inducing apoptosis of mouse prostatic cancer RM-1 cells in vitro].

OBJECTIVE: To study the inducing effect of trichosanthin on the apoptosis of mouse prostatic cancer RM-1 cells and its mechanism. METHODS: MTT assay was used to identify the effect of trichosanthin on RM-1 cells in vitro. The cells apoptosis was detected by Hoechest 33258 fluorescent staining and flow cytometry. The levels of bax proteins were detected by western blot analysis as well as their apoptosis rate. RESULTS: The IC50 value of trichosanthin for RM-1 cell was 117.32 mg/L. Cell cycle was analysised by flow cytometry, trichosanthin induced an arrest in G0/G1 phase. Hoechest 33258 fluorescent staining showed typical nucleolus changes in apoptosis cells. Expression of bax was up-regulated at protein levels in a time-dependent manner. CONCLUSION: Trichosanthin can induce apoptosis in RM-1 cells. The induction of apoptosis is a very important mechanism of trichosanthin to inhibit prostatic cancer.