[Effect of ZnSO4 on L-lactic acid production by Rhizopus oryzae].

OBJECTIVE: To improve the yield and quality of L-lactic acid by Rhizopus oryzae, we aim to understand the relationship between inorganic salts utilization and the L-lactic acid metabolism of the strain RLC41-6, through systematic analysis of the effects of zinc ion concentration on the production of L-lactic acid and the Lactic Dehydrogenase (LDH) activity. METHODS: Rhizopus oryzae was cultured at 36 degrees C for 36h with different quantity of ZnSO4 in fermentation medium. The fermentation products were monitored by reversed-phase high performance liquid chromatography (RP-HPLC), LDH isoenzyme composition in the cell was analysed by non-denatured polyacrylamide gel electrophoresis (PAGE). RESULTS: Our results showed that the concentration of ZnSO4 in medium could modulate the expression of LDH isoenzyme except LDH1, especially stimulated the expression of LDH4 and LDH5. When initial concentration of ZnSO4 is above 0.02%, the LDH4 and LDH5 reached the highest level. However, the activity of LDH was inhibited by higher concentration zinc ion in extracellular environment. When ZnSO4 concentration is 0.02%, LDH activity reaches its maximum 200U/mL, the HPLC assay showed only L-lactic in the fermentation products (137 g/L), while the conversion rate of glucose to lactic acid is 91%. CONCLUSION: Zinc ion can regulate the metabolic processes of Rhizopus oryzae and modulate the types of the final fermentation products. An optimal concentration of ZnSO4 can not only facilitate the LDH expression but also prevent pyruvate from transformation into the malic acid and fumaric acid during the metabolism process, thereby enhance the metabolism of glucose to lactic acid of Rhizopus oryzae.

Structural characterisation and anti-ageing activity of extracellular polysaccharide from a strain of Lachnum sp.

A homogeneous extracellular polysaccharide of Lachnum YM261(LEPS-1) with a molecular weight of 21670Da was characterised. According to HPGPC, IR, periodate oxidation and Smith degradation, GC-MS and (1)H NMR analysis, the results indicated that LEPS-1 was a glucan linked by the ß-(1→3)-d-pyran glycosidic bond. The effect of LEPS-1 on anti-ageing in d-gal model mice was also studied. It was found that LEPS-1 significantly increased the activities of antioxidant enzymes (i.e. SOD superoxide dismutase, CAT catalase, GSH-PX glutathione peroxidase) and decreased malondialdehyde (MDA) content in liver, brain and serum of d-gal model mice. These results showed that LEPS-1 had a strong anti-ageing activity.

[Production of ligninase by co-fermentation of Coprinus comatus and Trichoderma reesei].

In order to enhance the utilization efficiency, reduce the environmental pollution of traditional chemical treatment and the agriculture waste incineration; we studied the ligninase production by Coprinus comatus, Aspergillus niger and Trichoderma reesei through the plate screening. The results showed that C. comatus mixed culture with T. reesei have a good compatibility and higher yields of Laccase. On the basis of this pre-experiment, we studied the optimal conditions of mixed culture for enzyme production. Under the optimal conditions: the inoculation proportion of C. comatus and T. reesei (5:2), the interval of time (12 h), the temperature 260C, the shake rotation speed 150 r/min, fermented for 3 days, the Laccase activity reached 3267.1 U/mL, increased by 106% contrasted with single culture of C. commatus.

[Progress in study on microbial enzymes for the metabolism of environmental refractory organic compounds].

With the rapid development of socialization and industrialization, more and more pollutes were produced and discharged into natural environment. It is harmful to human health and life. These pollutes included refractory degradation organic compounds like PAHs, RDX, HMX, CL-20, PCBs and alkanes and their relative substances. Various compounds exist in nature with long life span. They are the most hazardous than other organics. The impact of pollutes can be treated by microorganisms. Results showed that it is an effective way for bioremediation of these pollutes with microbial metabolism or cometabolism. A few key enzymes, mainly oxidative and reductive enzymes, connected with the first step of initial degradation. Normally, enzymes grouped with other active fraction on the cell membrane are composed of one oxidative and reductive system for substrates oxidation. The metabolic intermediates can be used with TCA by microorganisms. The pathways of metabolism and the key enzymes were summarized. The further research topics should be focused on microorganism screen and its relative enzyme, pathway and mechanism of metabolism or cometabolism for such compounds degradation, and the result was hoped for the environmental protection.

[Investigation of fucoidanase by FTIR spectra].

Fucoidanase was isolated and purified from marine fungus LD8 by solid state fermentation, extraction with citric acid buffer, acetone precipitatation and column chromatography on Sephadex G-100. A single band on PAGE shows that pretty pure fucoidanase has been obtained. FT-IR spectra and its derivation, self-deconvolution and curve-fitting methods were used to analyze the secondary structure of the fucoidanase. Composite bands of the amide I and amide III were studied by using Fourier self-deconvolution (FSD) with an enhancement factor of K = 2.2 and a half width of 20.2 cm(-1). The relative average fractions of alpha-helix, beta-sheet, random coil, beta-turn are 11.5%, 58.6%, 14.5% and 15.9%, respectively, according to amide I region, while the content of alpha-helix is 12%, beta-sheet 57.3%, random coil 14.5%, and beta-turn 16.3% on amide III region. In other words, both the conclusions were exactly consistent. All the above results show that beta-sheet was the dominant component, which is about 58%, and that beta-turn is about 15%, random coil 15%, and alpha-helix 12% at room temperature.

Diastereomeric quinolinone alkaloids from the marine-derived fungus Penicillium janczewskii.

From Penicillium janczewskii, obtained from a marine sample, two new diastereomeric quinolinones, 3S,4R-dihydroxy-4-(4'-methoxyphenyl)-3,4-dihydro-2(1H)-quinolinone (1) and 3R,4R-dihydroxy-4-(4'-methoxyphenyl)-3,4-dihydro-2(1H)-quinolinone (2), were identified, along with two known alkaloids, peniprequinolone (3) and 3-methoxy-4-hydroxy-4-(4'-methoxyphenyl)-3,4-dihydro-2(1H)-quinolinone (4). Cytotoxicity testing on eight tumor cell lines revealed a moderate specificity of 2 on SKOV-3 cells.

[Production and properties of chitinase from Beauveria bassiana Bb174 in solid state fermentation].

This paper studied the chitinase production of Beauveria bassiana Bb174 under solid state fermentation condition. The optimal medium consisted of wheat bran and silkworm chrysalis at the ratio of 4:1, supplemented with 1 g peptone L(-1) as nitrogen source and some other mineral nutrients. The enzyme activity reached 126 units per gram dry medium after cultured for 2 days at 28 degrees C and natural pH by inoculated 3 ml spore suspension into this medium. The optimal temperature and pH for chintinase production were 40 degrees C and 5.0, respectively. The temperature to lose 50% activity of the enzyme was 48 degrees C after incubated at 30-70 degrees C for 1 h. The enzyme was stable at 30-40 degrees C and pH 4-6, and the Km and Vmax values were 0.52 mg x ml(-1) and 0.7 deltaE680 x h(-1), respectively.