This Mini-Review summarizes the historic developments and technological achievements in the biotechnological production of glutathione in the past 30 years. Glutathione is the most abundant non-protein thiol compound present in living organisms. It is used as a pharmaceutical compound and can be used in food additives and the cosmetic industries. Glutathione can be produced using enzymatic methods in the presence of ATP and its three precursor amino acids (L-glutamic acid, Lcysteine, glycine). Alternatively, glutathione can be produced by direct fermentative methods using sugar as a starting material. In the latter method, Saccharomyces cerevisiae and Candida utilis are currently used to produce glutathione on an industrial scale. At the molecular level, the genes gshA and gshB, which encode the enzymes γ- glutamylcysteine synthetase and glutathione synthetase, respectively, have been cloned from Escherichia coli and over-expressed in E. coli, S. cerevisiae, and Lactococcus lactis. It is anticipated that, with the design and/or discovery of novel producers, the biotechnological production of glutathione will be further improved to expand the application range of this physiologically and medically important tripeptide.

Pyruvic acid is an important organic acid widely used in the chemical and drug, as well as agrochemical, industries. Compared with the chemical method, biotechnological production of pyruvic acid is an alternative approach because of the low cost. An overview of biotechnological production of pyruvate, including direct fermentative production employing eukaryotic and prokaryotic microorganisms, production by a resting cell method and an enzymatic method as well as the recovery of pyruvate, is discussed. A multi-vitamin auxotrophic yeast strain, Torulopsis glabrata, has been used in the commercial production of pyruvate; emphasis is therefore placed on the mechanism and characteristics of pyruvate production by this strain.

Poly-3-hydroxybutyrate (PHB) is mainly accumulated by Ralstonia eutropha under unbalanced growth conditions, which limits its production in batch or fed-batch modes. The continuous production of PHB was investigated in a two-stage continuous culture system. The first-stage produced cell mass giving the maximal cell dry weight of 27.1g l−1 at 0.21h−1 of dilution rate. High specific cell growth rate results in the decrease of PHB synthesis under glucose-limited and nitrogen-rich conditions in the first-stage. The second-stage produced PHB giving the maximal PHB concentration of 47.6g l−1 at 0.14 h−1 of dilution rate. Specific PHB synthetic rate reached highest value at low dilution rate under nitrogen-limited condition in the second-stage, and decreased with the increase of ammonium concentration in the culture. In the continuous culture system, the maximal PHB productivity could reach 1.43g l−1h−1 at a dilution rate of 0.12h−1, but with relatively low PHB content of 47.6%. Maximal yield of PHB on glucose could reach 0.36g g−1 glucose at 0.075h−1 of dilution rate with relatively high PHB productivity of 1.23g l−1h−1 and PHB content of 72.1%, respectively.

pH is one of the most important environmental factors for cell growth and product formation. Batch microbial transglutaminase (MTG) fermentation by Streptoverticillium mobaraense WSH-Z2 at various pH values ranging from 5.0 to 8.5 was studied. A pH-shift strategy was developed to maximize MTG production in batch MTG fermentation. Based on time courses of the specific cell growth rate and specific MTG formation rate, a two-stage pH-shift strategy in which pH 7.0 was controlled at first 13 h, and then switched to 6.5 after 13 h was developed. By applying this pH-shift strategy in MTG fermentation, the maximal MTG activity and productivity had a significant improvement and reached 3.40u/ml and 81.4u/l/h, respectively, compared to those of constant pH operation (2.90u/ml and 61.4u/l/h).

The production of a novel polygalacturonic acid bioflocculant REA-11 from a newly isolated strain, Corynebacterium glutamicum CCTCC M201005, was investigated. Sucrose was chosen as a carbon source for REA-11 production. Complex nitrogen sources containing urea and an organic nitrogen compound enhanced both bacterial growth and REA-11 production, among which urea plus corn steep liquor was shown to be the most effcient combination. A cost-effective medium for REA-11 production mainly comprised 17g/l sucrose, 0.45g/l urea, and 5ml/l corn steep liquor, under which conditions the flocculating activity reached 390U/ml. The molar ratio of carbon to nitrogen (C/N) significantly affected REA-11 production, where a C/N ratio of 20: 1 was shown to be the best. Interestingly, by simultaneously feeding sucrose and urea at a C/N ratio of 20: 1 at 24h of fermentation, REA-11 production (458U/ml) was enhanced by 17% compared to the control. In a 10 l jar fermentor, lower dissolved oxygen tension was favorable for REA-11 production: a flocculating activity of 520U/ml was achieved at a kLa of 100h 1. REA-11 raw product is relatively thermo-stable at acidic pH ranges of 3.0-6.5. Preliminary application studies showed that REA-11 had stronger flocculating activity to Kaolin clay suspension compared to chemical flocculants. In addition, the capability of decolorizing molasses wastewater indicates the industrial potential of this novel bioflocculant.

生物修复是处理石油污染水体效果最好的一种方法，具有广阔的应用前景。本文简述了石油的组成、生物修复的概念及类型，对石油烃的微生物摄取、降解机制、生物修复的影响因素及强化途径等进行了详细论述，并对石油污染水体生物修复的现状及今后的发展趋势进行了讨论。

根据GC2MS分析，垃圾渗滤液中有机组分大多是难生物降解的有机化合物，如酚类、杂环类、杂环芳烃、多环芳烃类化合物,约占渗滤液中有机组分的70%以上。本文对渗滤液中典型有机化合物在电化学氧化和厌氧生物组合工艺系统中的降解特性进行了系统研究。结果表明，在电化学处理系统中，杂酚类、酰胺类、苯并噻唑、苯醌、喹啉、萘等有机化合物降解速率高于外222羟基桉树脑和异喹啉等化合物，但前者在厌氧生物处理系统中去除率低；渗滤液原水经过电化学氧化处理后，挥发性脂肪酸（VFA）含量从原水中的0168%增加到电化学出水中的16118%；此组合工艺能够显著降低因渗滤液复杂组分间的增效协同作用和拮抗作用而引起的毒性，系统出水可生化性增强，为进一步研究垃圾渗滤液的处理技术和进行该组合处理系统的大规模开发提供参考。

以放射型根瘤菌（Rhizobium radiobacter）WSH2601为出发菌株，经紫外线和亚硝基胍复合诱变，获得遗传稳定性好的抗放线菌素D突变株WSH-F06。在摇瓶中考察了碳、氮源等营养条件以及接种量、装液量和初始pH等环境条件对突变株WSH-F06细胞生长和积累辅酶Q10的影响。通过诱变和优化发酵条件，突变株WSH-F06的辅酶Q10产量和胞内含量分别达到34mg/L和2.4mg/g，比出发菌株在同样条件下提高了16%。

This paper studied the effect of pH and the viscosity of feed solution on the mass transfer in two different specifications of hydrophobic hollow fiber membrane contactors. Experimental results showed that the pH of the feed had a significant effect on the rate of mass transfer, the flux and the removal efficiency of easily ionized volatile compounds (VCs), such as ammonia. In unbuffered feed solutions, both the resistance of membrane and the resistance of feed side were affected by the pH of feed and both of them had contributions to the overall mass transfer. A model, 1/k=(1/kf+1/km)1/a2NH3, was proposed to predict the effect of pH and gave good agreement with the experimental data for the two contactors. The relationship between viscosities and the mass transfer coefficient could be described by 1/K=(1/Kf+1/Km)=(η2/η1) 0.33. Based on our experiments, the change of the viscosities in the concentration range of ammonia from 50 to 10,000mg l−1 caused about 3-4% variation of the mass transfer coefficients. Moreover, it may be more suitable to use the equilibrium concentrations of volatile species instead of the total concentrations of VCs to estimate mass transfer coefficients, removal efficiency and flux. Experimental results also revealed that the choice of the pH of feed might be one of the most crucial factors for removing easily ionized VCs, such as ammonia, from water and wastewater.

The chemical cleaning of polysulphone (PS) ultrafilters fouled during filtration of the glutamic fermentation broths was throughly investigated in this paper. The results demonstrated that the cleaning efficiency was strongly dependent on the cleaning mode and conditions, including agent concentration, cleaning temperature and time. As compared to the cleaning efficiency of two-step method, the combined simultaneous process (CSP) had merit. The cleaning kinetic equation was established and the active energy and rate constant of cleaning reactions were attained based on the first-order reaction and Arrhenius form. So, the cleaning ability and rate of different CSPs could be evaluated. Sodium dodecyl sulfate (SDS, C12H25OSO3Na) CSP achieved the strongest cleaning power and hydrogen peroxide (H2O2) CSP had the fastest cleaning rate. Also, the scanning electron microscopy (SEM) photographs of cleaned membrane surfaces were taken to directly observe the cleaning efficiency of different CSPs.