Insights into laccase producing organisms,fermentation states,purification strategies,and biotechnological applications

Laccases are phenol oxidases belonging to the superfamily of multicopper oxidases and are found in bacteria, fungi, lichens, higher plants, and insects. Over the past few decades, laccases and laccase mediator systems (LMS) have found uses in a wide range of technological applications such as textile dye decolorization, industrial wastewater detoxification, pulp bleaching, chemical synthesis, and development of miniaturized biosensors. This has encouraged numerous studies to find and purify laccases with exploitable characteristics. The main aim of the present review is to summarize the rich literature data gained in recent years from the studies on laccases, focusing on the organisms that produce them, the methods used for screening, laccase activity assays, purification strategies, and the application of laccases as eco‐friendly biocatalysts. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1443–1463, 2015     

油藏注入水靶向脱硫潜力的高温脱硫菌群富集驯化

【背景】海上油田见聚后产出水硫化物超标,影响到注聚水的配聚黏度,采用生物脱硫时,由于常规除硫菌难以适应除油后产出液的高温,使得脱硫效果不佳。【目的】分析海上采出液水处理过程的菌群结构,明确生物处理各节点的菌群构成变化;开展耐高温脱硫菌驯化筛选,获得耐高温的高效脱硫菌。【方法】采集来自胜利油田海三站的水样,以16S rRNA基因高通量测序技术分析样本菌群结构,并分别在不同温度(55、60和65℃)下的无机富集培养基中进行多轮转接驯化,结合常压室温等离子体(atmospheric and room temperature plasma, ARTP)诱变技术筛选获得耐高温的脱硫菌群,采用宏基因组测序技术分析富集菌群的组成,并测定其脱硫能力。【结果】处理前的采出液水样含有较多的嗜热菌和硫酸盐还原菌,如Thermodesulfovibrio、Pseudothermotoga、Thermolithobacter、Fervidobacterium、Thermovenabulales和Pseudomonas;以厌氧气浮除油工艺处理的出水中,嗜氢菌属(Hydrogenophilus)成为最主要的优势菌,...     

Comparisons Between the Kinetic Behaviour of the Muscle Carnitine Palmitoyltransferase I of a Higher and Lower Vertebrate

The V_max of rat muscle mitochondrial CPT I toward the coenzyme A derivatives of 16:0, 16:1n-7, 18:1n-9, and 22:6n-3 were far lower than those recorded previously for this enzyme in rat liver at the same temperature (37°C). However, the V_max of 7.0 nmol · min⁻¹ · mg mitochondrial protein⁻¹ for linoleoyl CoA (18:2n-6), which was the greatest recorded for the five acyl CoAs examined in muscle, was similar to that in liver. These comparisons presumably reflect a difference in the essential fatty acid requirements of these two rat tissues. Although the V_max values for CPT I in the musculature of a lower vertebrate (larval lamprey) at 20°C were similar to those exhibited toward the coenzyme A derivatives of 16:0, 16:1n-7, 18:1n-9, and 22:6n-3 by the CPT I of rat musculature at 37°C, the corresponding V_max toward 18:2n-6 (3.2 nmol · min⁻¹ · mg mitochondrial protein⁻¹) was lower. The latter relatively low activity may spare from oxidation this essential fatty acid, which is in low abundance in the diet of larval lampreys. Although the V_max values toward the four nonessential fatty acids in larval lamprey muscle were similar to those in rat muscle, the corresponding K_0.5 values were lower, thus indicating that the musculature of larval lampreys has a high capacity for energy generation through β-oxidation.     

Respiration-dependent proton translocation and the mechanism of protonmotive force generation in Nitrobacter winogradskyi

Abstract Proton translocation associated with electron flow to oxygen has been observed with cells of Nitrobacter winogradskyi in the presence of either potassium ferrocyanide or isoascorbate plus N , N , N ', N ' tetramethyl- p -phenylenediamine. The data are consistent with a proton pumping function for the terminal oxidase, cytochrome aa ₃, in this organism as the mechanism for generating a protonmotive force. The failure of previous work with Nitrobacter [4] to detect proton translocation linked to oxidation of nitrite, the physiological substrate, is discussed.     

高碘酸钠和戊二醛交联法构建的R-藻红蛋白-C-藻蓝蛋白交联物能量传递效率的比较研究

从单细胞蓝藻钝顶螺旋藻中纯化C-藻蓝蛋白,从海洋红藻多管藻纯化R-藻红蛋白.分别用高碘酸钠氧化法和戊二醛法将二者共价连接为R-藻红蛋白-C-藻蓝蛋白交联物,再用Sephadex G-200柱层析纯化.光谱分析表明,用两种方法构建的共价交联物都可以将激发能从R-藻红蛋白传递到C-藻蓝蛋白.二者相比,高碘酸钠氧化法构建的共价交联物的能量传递效率更高.     

Weak phylogenetic signal in physiological traits of methane‐oxidizing bacteria

The presence of phylogenetic signal is assumed to be ubiquitous. However, for microorganisms, this may not be true given that they display high physiological flexibility and have fast regeneration. This may result in fundamentally different patterns of resemblance, that is, in variable strength of phylogenetic signal. However, in microbiological inferences, trait similarities and therewith microbial interactions with its environment are mostly assumed to follow evolutionary relatedness. Here, we tested whether indeed a straightforward relationship between relatedness and physiological traits exists for aerobic methane‐oxidizing bacteria (MOB). We generated a comprehensive data set that included 30 MOB strains with quantitative physiological trait information. Phylogenetic trees were built from the 16S rRNA gene, a common phylogenetic marker, and the pmoA gene which encodes a subunit of the key enzyme involved in the first step of methane oxidation. We used a Blomberg's K from comparative biology to quantify the strength of phylogenetic signal of physiological traits. Phylogenetic signal was strongest for physiological traits associated with optimal growth pH and temperature indicating that adaptations to habitat are very strongly conserved in MOB. However, those physiological traits that are associated with kinetics of methane oxidation had only weak phylogenetic signals and were more pronounced with the pmoA than with the 16S rRNA gene phylogeny. In conclusion, our results give evidence that approaches based solely on taxonomical information will not yield further advancement on microbial eco‐evolutionary interactions with its environment. This is a novel insight on the connection between function and phylogeny within microbes and adds new understanding on the evolution of physiological traits across microbes, plants and animals.     

fliY基因失活减弱沙福芽孢杆菌ST7菌株的锰氧化能力

【背景】沙福芽孢杆菌ST7菌株具有较强的锰氧化能力,但其分子机制不清楚。【目的】着重研究鞭毛马达开关蛋白基因(fliY)对沙福芽孢杆菌锰氧化能力的影响。【方法】根据同源重组原理,以沙福芽孢杆菌ST7菌株为起始菌株,构建fliY基因敲除的突变株ΔfliY,测定菌落迁徙、细菌生物膜和锰氧化率等,研究fliY基因突变后菌株的运动能力、生物膜生成和锰氧化能力是否发生变化。【结果】经克隆测序,证实突变株ΔfliY中fliY基因的后半段被卡纳霉素抗性基因取代,fliY基因失活;与野生型菌株ST7相比,突变株ΔfliY在全营养的LB培养基中生长变化不大,但在含锰的PYCM培养基中,突变株的生长速度减慢、菌落较小、生物膜生成量显著下降,运动性和锰氧化能力分别下降65%和20%。【结论】fliY基因不仅影响菌株的生长和运动,而且参与细菌的趋化和锰氧化等生物学过程。     

Water oxidation chemistry of photosystem II

Photosystem II (PSII) uses light energy to split water into protons, electrons and O2. In this reaction, nature has solved the difficult chemical problem of efficient four-electron oxidation of water to yield O2 without significant amounts of reactive intermediate species such as superoxide, hydrogen peroxide and hydroxyl radicals. In order to use nature's solution for the design of artificial catalysts that split water, it is important to understand the mechanism of the reaction. The recently published X-ray crystal structures of cyanobacterial PSII complexes provide information on the structure of the Mn and Ca ions, the redox-active tyrosine called YZ and the surrounding amino acids that comprise the O2-evolving complex (OEC). The emerging structure of the OEC provides constraints on the different hypothesized mechanisms for O2 evolution. The water oxidation mechanism of PSII is discussed in the light of biophysical and computational studies, inorganic chemistry and X-ray crystallographic information.     

厌氧氨氧化体的组成、结构与功能

厌氧氨氧化(Anammox)是微生物和环境领域的研究热点之一。厌氧氨氧化菌(AnAOB)是Anammox的功能载体。不同于大部分原核微生物,AnAOB具有独特的细胞器——厌氧氨氧化体,它是进行Anammox代谢的场所。研究厌氧氨氧化体有助于探明厌氧氨氧化菌的代谢特性。本文综述了厌氧氨氧化体的组成、结构与功能,以期为从事Anammox研究的同行提供参考。