一个新的高温产氢菌及产氢特性的研究

利用Hungate滚管技术从西藏山南地区热泉淤泥中分离到一株高温产氢的厌氧发酵细菌T42。菌株T42革兰氏染色反应为阴性,但KOH裂解试验证实其为革兰氏阳性杆菌。菌体大小为0.7μm~0.9μm×3.2μm~7μm,不运动,不产芽孢。其生长温度范围为32℃~69℃,最适生长温度为60℃~62℃,生长pH范围为5.0~8.8,最适生长pH为7.0~7.5,代时30min。有机氮源是T42菌株的必需生长因子。菌株T42利用淀粉、纤维二糖、蔗糖、麦芽糖、糊精、果糖、糖原和海藻糖等底物生长并发酵产氢,发酵葡萄糖的终产物为乙酸、乙醇、H2和CO2。G C含量为31.2mol%。系统发育分析表明菌株T42与Thermobrachium celere和Caloramator indicus位于同一分支,生理生化特征也表明菌株T42应是Thermobrachium属的一个新菌株,在中国普通微生物菌种保藏中心的保藏号为AS1.5039。菌株T42的最佳产氢初始pH为7.2,最佳产氢温度为62℃,其氢转化率为1.06mol H2/mol葡萄糖,最大产氢速率为24.0mmol H2/gDW/h。20mmol/L的Mg2 和2mmol/L的Fe2 可分别提高菌株T42的产氢量20%和23.3%,而Ni2 对其产氢无明显的作用。当菌株T42和热自养甲烷热杆菌(Methanothermobacter thermautotrophicus)Z245共培养时,由于降低了氢分压,使其葡萄糖利用率和氢产量分别提高1倍和2.8倍,发酵产物乙酸和乙醇的比例也从1提高到1.7。     

A NEWLY ANTI-Streptococcus suis BACTERIOCIN PRODUCING STRAIN FROM UNWEANED PIGLETS FECAL MATTER: ISOLATION, PRELIMINARY IDENTIFICATION, AND OPTIMIZATION OF MEDIUM COMPOSITION FOR ENHANCED BACTERIOCIN PRODUCTION

A newly isolated anti-Streptococcus suis bacteriocin-producing strain LPL1-5 was obtained from healthy unweaned piglets' fecal matter, and was designated as Lactobacillus pentosus LPL1-5 based on morphology, biochemical properties, and 16S rDNA sequencing analysis. The medium composition for enhanced bacteriocin production by L. pentosus LPL1-5 was optimized by statistical methodology. Yeast extract, K(2)HPO(4)?·?3H(2)O, and MnSO(4)?·?H(2)O were identified as significant components influencing pentocin LPL1-5 production using the Plackett-Burman method. Response surface methodology was applied for further optimization. The concentrations of medium components for enhanced pentocin LPL1-5 production were as follows (g/L): lactose 20.00, tryptone 10.00, beef extract 10.00, yeast extract 14.00, MnSO(4)?·?H(2)O 0.84, K(2)HPO(4)?·?3H(2)O 4.92, triammonium citrate 2.00, Na-acetate 5.00, MgSO(4)?·?7H(2)O 0.58, Tween 80 1.00. Under the optimized condition, a value of 3154.65?±?27.93 IU/mL bacteriocin activity was achieved, which was 4.2-fold that of the original medium.     

A versatile method for preparation of hydrated microbial–latex biocatalytic coatings for gas absorption and gas evolution

We describe a latex wet coalescence method for gas-phase immobilization of microorganisms on paper which does not require drying for adhesion. This method reduces drying stresses to the microbes. It is applicable for microorganisms that do not tolerate desiccation stress during latex drying even in the presence of carbohydrates. Small surface area, 10-65?μm thick coatings were generated on chromatography paper strips and placed in the head-space of vertical sealed tubes containing liquid to hydrate the paper. These gas-phase microbial coatings hydrated by liquid in the paper pore space demonstrated absorption or evolution of H(2), CO, CO(2) or O(2). The microbial products produced, ethanol and acetate, diffuse into the hydrated paper pores and accumulate in the liquid at the bottom of the tube. The paper provides hydration to the back side of the coating and also separates the biocatalyst from the products. Coating reactivity was demonstrated for Chlamydomonas reinhardtii CC124, which consumed CO(2) and produced 10.2?±?0.2?mmol?O(2)?m(-2)?h(-1), Rhodopseudomonas palustris CGA009, which consumed acetate and produced 0.47?±?0.04?mmol?H(2)?m(-2)?h(-1), Clostridium ljungdahlii OTA1, which consumed 6?mmol CO?m(-2)?h(-1), and Synechococcus sp. PCC7002, which consumed CO(2) and produced 5.00?±?0.25?mmol O(2)?m(-2)?h(-1). Coating thickness and microstructure were related to microbe size as determined by digital micrometry, profilometry, and confocal microscopy. The immobilization of different microorganisms in thin adhesive films in the gas phase demonstrates the utility of this method for evaluating genetically optimized microorganisms for gas absorption and gas evolution.     

高效产氢细菌新种--Ethanologenbacterium sp.X-1的分离鉴定及其产氢效能

为获得高效产氢发酵细菌 ,采用改进的厌氧Hungate培养技术 ,从生物制氢反应器CSTR中分离一株产氢细菌X 1。对该株细菌进行了形态学特征、生理生化指标、16SrDNA和 16S 2 3SrDNA间隔区序列分析等研究。结果表明与最相近的种属Clostridiumcellulosi和Acetanaerobacteriumelongatum等的 16SrRNA基因序列同源性为 94 %以下。16S 2 3SrRNA间隔区基因序列比对分析显示保守区域仅为tRNAAla和tRNAIle序列 ,其它可变部位没有同源性区域 ,鉴定为新属Ethanologenbacteriumsp .。该株细菌为专性厌氧杆菌 ,代谢特征为乙醇发酵 ,葡萄糖发酵产物主要为乙醇、乙酸、H2 和CO2 。在pH4 0和 36℃条件下最大产氢速率是 2 8 3mmolH2 (gdrycell·h)。经鉴定和产氢效能分析表明该菌株是一新属的高效产氢细菌     

木糖发酵产氢菌的筛选及其生长产氢特性研究

利用改进的Hungate厌氧技术, 从牛粪堆肥中分离出一株能有效利用木糖发酵产氢的中温菌HR-1。通过16S rRNA系统发育树分析表明, 菌株 HR-1 与丙酮丁醇梭菌Clostridium acetobutylicum ATCC 824 相似性最高为96%, 结合生理生化和生长特性分析表明, HR-1是梭菌属Clostridium的一个新种, 命名为Clostridium sp. HR-1。菌株HR-1为单胞生长的规则杆状菌(0.3 mm ~0.6 mm)×(1.4 mm~2.3 mm), 革兰氏染色为阴性, 无荚膜、无鞭毛、表面光滑、无明显凸起, 专性厌氧菌。HR-1可在10°C~45°C, pH 4.0~10.0条件下生长; 37°C和pH 8.0分别为其最适生长条件。发酵PYG的主要发酵产物有氢气、二氧化碳、乙酸、丁酸及少量乙醇。HR-1可以利用有机氮源和无机氮源生长并产氢, 酵母提取物是其最佳产氢氮源。HR-1在木糖浓度为3 g/L和初始pH 6.5条件下, 其比产氢量为1.84 mol-H2/mol-木糖, 最大比产氢速率为10.52 mmol H2/h·g-细胞干重。HR-1可以亦利用葡萄糖、半乳糖、纤维二糖、甘露糖和果糖等碳源生长并发酵产氢, 发酵葡萄糖时比产氢量为2.36 mol-H2/mol-葡萄糖。     

产氢菌Enterobacter sp.和Clostridium sp.的分离鉴定及产氢特性

在高温水体中分离得到2株具有较高产氢活性的微生物菌株Z-16和C-32。根据两菌株的16SrDNA序列分析,初步鉴定菌株Z-16为Enterobactersp.,菌株C-32为Clostridiumsp.。研究了起始pH值、反应温度、碳源等对菌株放氢活性的影响。菌株Z-16的最适产氢条件为:反应系统起始pH7·0,反应温度35℃,以蔗糖为产氢底物。在最适条件下,菌株Z-16的氢转化率为2·68molH2/mol蔗糖。菌株C-32的最适产氢条件为:反应系统起始pH8·0,反应温度35℃,以麦芽糖为产氢底物。在最适条件下,菌株C-32的氢转化率为2·71molH2/mol麦芽糖。以葡萄糖为碳源时,菌株Z-16和菌株C-32的氢转化率分别为2·35和2·48molH2/mol葡萄糖。     

Microalgal biomass production and on-site bioremediation of carbon dioxide, nitrogen oxide and sulfur dioxide from flue gas using Chlorella sp. cultures

The growth and on-site bioremediation potential of an isolated thermal- and CO?-tolerant mutant strain, Chlorella sp. MTF-7, were investigated. The Chlorella sp. MTF-7 cultures were directly aerated with the flue gas generated from coke oven of a steel plant. The biomass concentration, growth rate and lipid content of Chlorella sp. MTF-7 cultured in an outdoor 50-L photobioreactor for 6 days was 2.87 g L?1 (with an initial culture biomass concentration of 0.75 g L?1), 0.52 g L?1 d?1 and 25.2%, respectively. By the operation with intermittent flue gas aeration in a double-set photobioreactor system, average efficiency of CO? removal from the flue gas could reach to 60%, and NO and SO? removal efficiency was maintained at approximately 70% and 50%, respectively. Our results demonstrate that flue gas from coke oven could be directly introduced into Chlorella sp. MTF-7 cultures to potentially produce algal biomass and efficiently capture CO?, NO and SO? from flue gas.     

Relationships between cellobiose catabolism, enzyme levels, and metabolic intermediates in Clostridium cellulolyticum grown in a synthetic medium

Continuous cultures, under cellobiose sufficient concentrations (14. 62 mM) using a chemically defined medium, were examined to determine the carbon regulation selected by Clostridium cellulolyticum. Using a synthetic medium, a q(cellobiose) of 2.57 mmol g cells(-1) h(-1) was attained whereas the highest value obtained on complex media was 0.68 mmol g cells(-1) h(-1) (Payot et al. 1998. Microbiology 144:375-384). On a synthetic medium at D = 0.035 h(-1) under cellobiose excess, lactate and ethanol biosynthesis were able to use the reducing equivalents supplied by acetic acid formation and the H(2)/CO(2) ratio was found equal to 1. At a higher dilution rate (D = 0.115 h(-1)), there was no lactate production and the pathways toward ethanol and NADH-ferredoxin-hydrogenase contributed to balance the reducing equivalents; in this case a H(2)/CO(2) ratio of 1.54 was found. With increasing D, there was a progressive increase (i) in the steady-state concentration of NADH and NAD(+) pools from 11.8 to 22.1 micromol (g cells) (-1), (ii) in the intracellular NADH/NAD(+) ratios from 0.43 to 1.51. On synthetic media, under cellobiose excess the carbon flow was also equilibrated by three overflows: exopolysaccharide, extracellular protein, and amino acid excretions. At D = 0.115 h(-1), 34% of the cellobiose consumed was converted into exopolysaccharides; this deviation of the carbon flow and the increase of the phosphoroclastic activity decreased dramatically the pyruvate excretion and explained the break in lactate production. Whatever the dilution rate, C. cellulolyticum, using ammonium and cellobiose excess, always spilled usual amino acids accompanied by other amino compounds. In vitro, GAPDH, phosphoroclastic reaction, alcohol dehydrogenase, and acetate kinase activities were high under conditions giving high in vivo specific production rates. There were also correlations between the in vitro lactate dehydrogenase activity and in vivo lactate production, but in contrast with the preceding activities, these two parameters decreased with D. All the results demonstrate that C. cellulolyticum was able to optimize carbon catabolism from cellulosic substrates in a synthetic medium.     

不同生境微生物转化H2/CO2产乙酸及其在合成气发酵中应用

【目的】合成气发酵对大力开发可再生资源和促进国家可持续发展具有重要意义,研究旨在探究不同生境微生物转化H2/CO2产乙酸及其合成气发酵的潜力。【方法】采集剩余污泥、牛粪、产甲烷污泥和河道底物样品在中温(37 °C)条件下生物转化H2/CO2气体,将来源于牛粪样品的H2/CO2转化富集物用于合成气发酵,通过454高通量技术和定量PCR技术分析复杂微生物群落的组成,GC气相色谱法检测气体转化产生的挥发性脂肪酸(VFAs)浓度。【结果】牛粪和剩余污泥微生物利用H2/CO2气体生成乙酸、乙醇和丁酸等,最高乙酸浓度分别为63 mmol/L和40 mmol/L,明显高于河道底物和产甲烷污泥样品的最高乙酸浓度3 mmol/L和16 mmol/L。牛粪和剩余污泥微生物中含有种类多样化的同型产乙酸菌,剩余污泥中同型产乙酸菌主要为Clostridium spp.、Sporomusa malonica和Acetoanaerobium noterae,牛粪中则为Clostridium spp.、Treponema azotonutricium和Oxobacter pfennigii。【结论】同型产乙酸菌的丰富度和数量两个因素都对复杂微生物群落转化H2/CO2产乙酸效率至关重要;转化H2/CO2得到的富集物可用于合成气发酵产乙酸和乙醇,这为基于混合培养技术的合成气发酵提供了依据。     

Metabolism of glucose and cellobiose by cellulolytic mesophilic Clostridium sp. strain H10.

The metabolism of strain H10, a cellulolytic mesophilic Clostridium sp., was studied on glucose and cellobiose as energy and carbon sources. The main products of fermentation of both sugars were acetate, lactate, and ethanol. At low sugar levels, molar growth yields were better for cellobiose than for glucose. In both cases, an inhibition of growth was observed between 1 and 2 g/liter and a total inhibition after the latter concentration. Inhibition was not the result of low pH due to acid formation; growth under static pH conditions was limited in the same way. On the other hand, acetate and lactate had no inhibitory effect when added at concentrations equal to the final titers. Concomitant with the inhibition of growth was a change in metabolic pathways for sugar concentrations between 1 and 2 g/liter, i.e., the production of lactate was higher. After complete inhibition of growth, an accumulation of carbohydrates which were neither glucose nor cellobiose was observed.     

Co-production of 3-hydroxypropionic acid and 1,3-propanediol from glycerol using resting cells of recombinant Klebsiella pneumoniae J2B strain overexpressing aldehyde dehydrogenase

The co-production of 3-hydroxypropionic acid (3HP) and 1,3-propanediol (PDO) from glycerol was studied using the resting cells of a recombinant Klebsiella pneumoniae J2B strain that overexpresses an aldehyde dehydrogenase (KGSADH). Active biomass was produced in a mineral salt medium containing yeast extract and glycerol under a range of aeration conditions, and shifted to potassium phosphate buffer containing glycerol for bioconversion. The microaerobic or anaerobic conditions were favorable for both the production of active biomass and subsequent bioconversion. At the flask level, the recombinant strain (2.0?g?CDW/L) grown under microaerobic conditions produced 43.2?mM 3HP and 59.0?mM PDO from glycerol (117?mM) in 30?min with a cumulative yield of 0.87?(mol/mol). The fed-batch bioconversion, which was performed in a 1.5-L bioreactor with 1.0?g?CDW/L at a constant pH?7.0 under anaerobic conditions, resulted in 125.6?mM 3HP and 209.5?mM PDO in 12?h with a cumulative overall productivity, yield, and maximum specific production rate of 27.9?mmol/L/h, 0.71 (mol/mol), and 128.5?mmol/g CDW/h, respectively. Lactate, succinate and 2,3-butanediol were the major by-products, whereas the production of acetate and ethanol was marginal. This is the first report of the simultaneous production of 3HP and PDO from glycerol using a resting cell system.     

Simultaneous saccharification and fermentation of acid-pretreated corncobs with a recombinant Saccharomyces cerevisiae expressing beta-glucosidase

To reduce the cellobiose inhibition of exoglucanase and endogulcanase and enhance cellulose hydrolysis during simultaneous saccharification and fermentation (SSF), a beta-glucosidase encoding gene named BGL1 was cloned from Saccharomycopsis fibuligera and integrated into the chromosomal rDNA region of the Saccharomyces cerevisiae industrial strain NAN-27 producing NAN-227. Compared with the parental strain, which had no detectable activity, the beta-glucosidase specific activity in NAN-227 was 1.02 IU/mg of protein. When cellobiose was used as the sole carbon source in a shake-flask, NAN-227 consumed 6.2g/L of cellobiose and produced 3.3g/L of ethanol in 48 h. The yield was 0.532 g/g. The parent strain only consumed 1.92 g/L of cellobiose and no ethanol was detected. During the SSF of acid-pretreated corncobs NAN-227 produced 20 g/L of ethanol at 72 h, which was similar to the parent strain when 20IU of beta-glucosidase/g of substrate was added.     

兼性厌氧复合菌群H纤维素降解和产乙醇能力及生态组成初探

通过限制性培养条件和连续继代培养,筛选获得了一组具有高效稳定降解纤维素能力的复合菌群H。该菌群在传代30代以上仍能保持各项性状稳定,其工作pH为6～9,3 d可以完全降解置于100 mL PCS缓冲液培养基中的滤纸,发酵液中能够检出1.54 g/L乙醇。通过16S rDNA扩增和DGGE的方法,对菌群在不同阶段的微生物组成进行了研究,确定了琥珀酸嗜热梭菌Clostridium thermo succinogene、产气荚膜梭菌Clostridium straminisolvens和紫色板蓝根梭菌Clostridium isatidis等多种可直接实现纤维素到乙醇转化的菌株。菌群通过菌种之间的协同作用,共同维持了体系的稳定及降解能力的稳定。明确菌系的组成,对于进一步研究菌群降解机理、优化菌群和提高乙醇产率意义重大。     

Continuous hydrogen production during fermentation of alpha-cellulose by the thermophillic bacterium Clostridium thermocellum

Continuous hydrogen (H2) production during fermentation of alpha-cellulose was established using the thermophillic, anaerobic bacterium Clostridium thermocellum ATCC 27405. The objectives of this work were to characterize growth of C. thermocellum, quantify H2 production and determine soluble end-product synthesis patterns during fermentation of a cellulosic substrate under continuous culture conditions. A 5 L working volume fermentor was established and growth experiments were maintained for over 3,000 h. Substrate concentrations were varied from 1 to 4 g/L and the feed was introduced with continuous nitrogen gas sparging to prevent clogging of the feed-line. The pH and temperature of the reactor were maintained at 7.0 and 600 degrees C, respectively, throughout the study. At concentrations above 4 g/L, the delivery of alpha-cellulose was impaired due to feed-line clogging and it became difficult to maintain a homogenous suspension. The highest total gas (H2 plus CO2) production rate, 56.6 mL L(-1) h(-1), was observed at a dilution rate of 0.042 h(-1) and substrate concentration of 4 g/L. Under these conditions, the H2 production rate was 5.06 mmol h(-1). Acetate and ethanol were the major soluble end-products, while lactate and formate were greatly reduced compared to production in batch cultures. Concentrations of all metabolites increased with increasing substrate concentration, with the exception of lactate. Despite a number of short-term electrical and mechanical failures during the testing period, the system recovered quickly, exhibiting substantial robustness. A carbon balance was completed to ensure that all end-products were accounted for, with final results indicating near 100% carbon recovery. This study shows that long-term, stable H2 production can be achieved during direct fermentation of an insoluble cellulosic substrate under continuous culture conditions.     

Characterization of a new xylanolytic bacterium, Clostridium xylanovorans sp. nov.

A new xylanolytic bacterium designated strain HESP1T (T = type strain) was isolated from a methanogenic digester. Strain HESP1T was a motile, rod shaped, spore-forming bacterium, which possessed a Gram-positive type cell wall. Glucose, fructose, lactose, trehalose, maltose, raffinose, sucrose, xylan, mannitol, cellobiose, galactose, mannose, melibiose, ribose were fermented to produce, acetate, butyrate, H2, CO2, formate, isobutyrate, and ethanol. Fumarate was fermented to acetate. Glycerol and methanol were also utilized. Sulfate, thiosulfate, nitrate, sulfur and fumarate were not used as electron acceptors. Strain HESP1T had a G + C content of 40 mol% and grew optimally at 37 degrees C and pH 7 on a fructose containing medium. Phylogenetically, strain HESP1T was most related to Clostridium aminovalericum (similarity of 94%) than to C. populeti, C. herbivorans and Eubacterium xylanophilum (average similarity of 92%), all members of subcluster XIVa of the low G + C containing Gram-positive branch. However, strain HESP1T shared little phenotypic and genotypic traits with C. aminovalericum and on the basis of this and phylogenetic evidence, we propose to tentatively designate strain HESP1T as a new species of the genus Clostridium, Clostridium xylanovorans sp. nov. The type strain is HESP1T (= DSM 12503).     

一株新型同型产乙酸菌Clostridium sp.的自养和异养生长特性

【背景】同型产乙酸菌是一类利用乙酰辅酶A途径固定CO_2合成自身细胞物质并生成乙酸、乙醇等代谢产物的厌氧菌群,其分布广泛、种类繁多且代谢多样。深入研究同型产乙酸菌菌株的代谢能力及特性,对探索该种群的生理生化特性及其环境作用至关重要。【目的】研究一株同型产乙酸菌Clostridium sp. BXX的最适培养条件及其自养与异养生长特性。【方法】设置BXX菌株培养温度10-55°C、初始pH 6.0-9.0、NaCl浓度0-2.0%、不同氮源,测定菌体细胞含量和产物生成浓度,确定菌株最适培养条件。研究BXX菌株分别以H_2/CO_2、合成气、CO、葡萄糖、1,2-丙二醇、甲酸钠、乙二醇甲醚、甘油、丙酮酸和乳酸为底物时的底物消耗、产物生成、菌体细胞含量和pH等,探究其自养和异养生长特性。【结果】BXX菌株的最适培养温度为30°C,初始pH为7.0,NaCl浓度为1.0%,氮源为酵母粉。BXX菌株能以H2/CO2、合成气、葡萄糖、1,2-丙二醇、甲酸钠、乙二醇甲醚和甘油为底物生长,不能以CO、丙酮酸或乳酸为底物生长。【结论】BXX菌株既能自养生长产乙酸,又能异养生长产乙醇。BXX菌株是乙酸发酵的优良菌种资源,有较好的工业应用潜力。     

Characterization of the cellulolytic and hydrogen-producing activities of six mesophilic Clostridium species

AIMS: To characterize cellulolytic, hydrogen-producing clostridia on a comparable basis. METHODS AND RESULTS: H(2) production from cellulose by six mesophilic clostridia was characterized in standardized batch experiments using MN301 cellulose, Avicel and cellobiose. Daily H(2) production, substrate degradation, biomass production and the end-point distribution of soluble fermentation products varied with species and substrates. All species produced a significant amount of H(2) from cellobiose, with Clostridium acetobutylicum achieving the highest H(2) yield of 2.3 mol H(2) mol(-1) hexose, but it did not degrade cellulose. Clostridium cellulolyticum and Clostridium populeti catalysed the highest H(2) production from cellulose, with yields of 1.7 and 1.6 mol H(2 )mol(-1) hexose from MN301 and 1.6 and 1.4 mol H(2) mol(-1) hexose from Avicel, respectively. These species also achieved 25-100% higher H(2) production rates from cellulose than the other species. CONCLUSIONS: These cellulolytic, hydrogen-producing clostridia varied in H(2) production, with Cl. cellulolyticum and Cl. populeti achieving the highest H(2) yields and cellulose degradation. SIGNIFICANCE AND IMPACT OF THE STUDY: The fermentation of cellulosic materials presents a means of H(2) production from renewable resources. This standardized comparison provides a quantitative baseline for improving H(2) production from cellulose through medium and process optimization and metabolic engineering.     

嗜热厌氧纤维素降解细菌的分离、鉴定及其系统发育分析

利用纤维素降解细菌和纤维素粘附的方法分别从新鲜牛粪、高温堆肥和本实验室保存的纤维素降解富集物中分离得到4株嗜热厌氧纤维素降解细菌。分离菌株为革兰氏染色阴性,直的或稍弯曲杆菌,菌体大小为0.4μm～0.6μm×3μm～15μm,严格厌氧,不还原硫酸盐,形成芽孢。多数芽孢着生于菌体顶端。分离菌株能利用纤维素滤纸、纤维素粉Whatman CFII、微晶纤维素、纤维素粉MN300和未经处理的玉米秆芯、甘蔗渣、水稻秸杆。分离菌株在pH6.2～8.9、温度45℃～65℃范围内利用纤维素,最适pH为7.0～7.5,最适温度为55℃～60℃,发酵纤维素产生乙醇、乙酸、H2和CO2。分离菌株还可利用纤维二糖、葡萄糖、果糖、麦芽糖、山梨醇作为碳源。部分长度的16S rDNA序列分析表明,分离菌株EVAI与Clostridium thermocellum具有99.8%相似性。     

Heterorhabditis atacamensis n. sp. (Nematoda: Heterorhabditidae), a new entomopathogenic nematode from the Atacama Desert, Chile

A new Heterorhabditis species of entomopathogenic nematode was isolated from soil of the Atacama Desert in Chile. The new species is characterized by morphometrics of the infective juvenile (IJ) with length (L)?=?611 (578-666)?μm, head to excretory pore length (EP)?=?115 (101-126)?μm, tail?=?69 (62-79)?μm long, (EP/tail)?×?100 (E%)?=?165 (149-182) and L/maximum body diameter (ratio a)?=?28 (25-31). The male has spicules 45 (40-49)?μm long, gubernaculum 20 (17-22)?μm long and (spicule length/anal body diameter)?×?100 (SW%)?=?205 (179-249). The hermaphroditic adult has shallow cuticular folds immediately anterior and posterior to the vulva, a slight post-anal swelling and a finely rounded tail terminus. Morphologically, H. atacamensis n. sp. resembles H. safricana, H. marelatus, H. downesi and H. amazonensis, but can be distinguished by characters of adult and IJ stages. In particular, for adult males, H. atacamensis n. sp. differs from H. amazonensis by the number and orientation of the genital papillae and from H. downesi by the position of the excretory pore; by the shape of the female tail terminus from H. downesi and by the position of the IJ hemizonid from H. marelatus. Heterorhabditis atacamensis n. sp. is further characterized by internal transcribed spacer (ITS) and D2D3 rDNA sequences, the closest species, H. safricana, being separated by 13?bp across 730?bp of the ITS (incorporating ITS1 (partial sequence), 5.8S (complete sequence), ITS2 (complete sequence)) and 5?bp across 592?bp of the partial 28S (incorporating D2D3) sequence. The morphological and molecular data confirm that H. atacamensis n. sp. is a valid species.     

杂色云芝产漆酶的发酵条件研究*

本文对杂色云芝（Coriolus versicolor）产漆酶的发酵条件作了研究。结果表明摇瓶实验产漆酶（Laccase）的最佳培养基成分为：可溶性淀粉 2g/L, NH4Cl 24mmol/L, 微量元素混合液 7ml/L, pH3.0柠檬酸—Na2HPO4缓冲溶液 0.01mol/L, KH2PO4 1.4×10-2 mol/L, MgSO4·7H2O 2.03×10-3mol/L, CaCl2·2H2O 6.8×10-4 mol/L, VB1 2.97×10-6 mol/L, 吐温80 4.0g/L, 愈创木酚0.01mmol/L, CuSO4 ·5H2O 0.005mmol/L,最佳发酵条件为培养基初始pH3.0, 菌体生长6d,培养基装量为250ml三角瓶中25ml培养液,25℃条件下振荡培养(150r/min)9d。