锰氧化菌Bacillus sp. MK3-1的Mn(Ⅱ)氧化特性和除锰能力研究

锰氧化微生物能够将可溶的Mn(II)氧化为不溶的锰氧化物沉淀, 因此在生物除锰研究上具有重要的应用价值。本研究从锰污染土壤中分离到一株锰氧化菌Bacillus sp. MK3-1, 该菌对MnCl2有较高抗性, 其最低抑制浓度(Minimal inhibitory concentration, MIC)为20 mmol/L。实验表明该菌在培养基中Mn(Ⅱ)的去除率高达96%, 同时将其制成固体包埋菌剂应用于含0.15 mmol/L的MnCl2水溶液实验, 结果表明其仍然具有稳定的除锰能力, 去除率为87.12%, 使溶液的终锰浓度符合国家排放标准。扫描电子显微镜观察和能谱分析实验表明, 实验产生的锰氧化物均匀地分布在Bacillus sp. MK3-1的细胞表面, 细胞表面含锰量为19.60% (W/W)。用简并引物扩增目前被认为催化锰氧化的多铜氧化酶基因mnxG, 获得了903 bp的基因片段, 其基因产物与已报道的多铜氧化酶具有86%的同源性。     

泥浸汁对太湖沉积物中的好氧可培养细菌多样性的影响

【目的】研究添加泥浸汁与否对太湖沉积物中可培养细菌的影响。【方法】采用R2A培养基和添加泥浸汁R2A培养基对沉积物中细菌进行分离培养,16S r RNA基因系统发育分析比较种群结构。【结果】培养基中添加泥浸汁,可使可培养细菌的种类数量增加到1.6倍。16S r RNA基因序列分析表明,培养的优势细菌类群存在明显差别。R2A培养基上生长的细菌主要为厚壁菌门(52%)、放线菌门(24%)、变形菌门(20%)和拟杆菌门(4%),其中大部分细菌与芽孢杆菌属、假单胞菌属、节杆菌属等关系密切;而添加泥浸汁的R2A培养基上生长的细菌则主要为变形菌门(40%)、放线菌门(35%)、厚壁菌门(22.5%)和拟杆菌门(2.5%),与鞘脂单胞菌属、芽孢杆菌属、副球菌属、节杆菌属等关系密切。【结论】添加泥浸汁原始营养因子可提高沉积物中可培养细菌的多样性,提高菌种可培养效率。     

一株重金属高耐受菌的分离及鉴定

利用含不同浓度的重金属选择性培养基,对采集的微生物样本进行分离,并筛选出一株超高耐受重金属菌ZM-12。对ZM-12的16S rDNA高变区序列进行BLAST比较和MEGA 4.0分析,结果通过同源进化树分析表明该菌属于肠杆菌属（Enterobacter）。对该菌进行生理生化实验、最低抑菌浓度（MIC）的测定和火焰原子吸收实验,结果表明：ZM-12属于革兰氏阴性杆菌,在不同种类的重金属培养基中,其MIC值各不相同,Cu2+、Pb2+、Mn2+、Ni2+对ZM-12的MIC值分别为22.33 mmol/L、14.48 mmol/L、>200 mmol/L、58.69 mmol/L。通过火焰原子吸收的方法,测定了ZM-12对培养基中重金属的去除率,培养一定时间后,分别测定了溶液中重金属Pb2+、Mn2+、Cu2+、Ni2+的浓度,得到其最大去除率分别达到97.68%、99.93%、41.23%、99.46%。该菌株的发现及鉴定为重金属污染环境的治理提供了参考。     

黄孢原毛平革菌生产锰过氧化物酶的发酵条件研究

目的 :研究黄孢原毛平革菌产锰过氧化物酶的发酵条件。方法 :对培养条件进行优化 ,采用正交设计法对培养基组分进行优化。结果与结论 :优化培养条件为 :接种量 1 6× 10 6 个孢子 L ,pH 4 4～ 4 8,温度 36℃～ 4 0℃ ,转数 12 0r/min。优化培养基参数为 :葡萄糖 5g L ,酒石酸铵 1 3mmol L ,吐温 - 80 1 2g L ,Mn2 + 0 9mmol L。     

普通和稀释培养基研究太湖沉积物可培养细菌的多样性

采用普通牛肉汁培养基和 10倍稀释的普通牛肉汁培养基 (以下简称稀释培养基 )研究太湖沉积物中细菌多样性 ,发现在稀释培养基上生长的细菌数量普遍是在普通牛肉汁琼脂培养基上生长的细菌数量的 3～ 5倍。分离得到纯培养物的 16SrDNA部分序列 (5′端约 5 0 0bp)分析表明 ,不同培养基上生长的优势细菌类群存在差别 :普通培养基生长的细菌主要为γ_Proteobacteria(35. 1% ) ,其次为Actinobacteria(2 4 5 % )和Firmicutes(2 2 . 3% )等类群 ,其中大部分细菌与假单胞菌属 (Pseudomoas)、芽孢杆菌属 (Bacillus)和节杆菌属 (Archrobacter)细菌的系统关系密切 ;稀释培养基生长的细菌则主要为Actinobacteria(2 7. 1% )、Firmicutes(2 5 . 7% )、α_Proteobacteria(2 1. 4 % )和γ_Proteobacteria(15. 7% )等类群 ,与芽孢杆菌属 (Bacillus) (2 5. 7% )发育系统关系密切的细菌为优势属。研究结果表明同时采用两种培养基有助于从太湖沉积物中分离到更多种微生物。     

苎麻脱胶菌群RAMCD407中优势菌的分离、鉴定及脱胶能力分析

【目的】以苎麻生物脱胶菌群RAMCD407为研究材料,分析其菌种功能,初步阐明菌群的种间协作机理。【方法】利用4种不同的培养基,对该菌群中的微生物进行分离培养,通过16S r RNA基因序列比对鉴定,将分离得到的菌株进行果胶酶活力、木聚糖酶活力和胶质去除率的测定与筛选。筛选得到的菌株重新组合成为复合菌系JHY,并分析各菌种对JHY的功能影响。【结果】共获得25个菌株,这25个菌株分别属于芽孢杆菌属、假单胞菌属、肠杆菌属、鲁梅利杆菌属、鞘氨醇杆菌属和微小杆菌属。从中筛选出6株细菌,分别为Y1、2H3、Y2、JY31、2H2和2H1,组成复合菌系JHY。经测定,2H2在复合菌系JHY中发挥重要作用,能提高复合菌系的果胶酶活力、木聚糖酶活力和胶质去除率;JY31的存在抑制了其它菌株的生长,降低了复合菌系JHY的酶活力和胶质去除率。【结论】2H2为复合菌系JHY的重要菌种,去除JY31可提高复合菌系JHY的脱胶效率。     

Bergey氏对细菌门的分类(续)

2.代谢硫破的细菌 硫杆菌属口汤iobacill,’,),硫化裂片菌属(Sulfolob“,), 硫小杆菌属(T为iobaet,,iu。),大单胞菌属(Macro- 。ooa,),旦日硫菌属(T乃10,“l,,,),硫螺菌属(T人10- J户‘ra)。 3.沉淀铁和镁载化物的细菌 梢铁曰科(Sideroeapsaeeae):鞘铁菌(51女roea娜a),瑙 里氏臼属(Na,’ ma,,扮lla),储菌属(oehrobi,‘。),铁 珠日属(sid行ococou,)。,十三.分:产生甲烧的细, 甲杭杆日科(Methanobacteriaeeae):甲烷杆菌属(M。- t汤‘,o吞‘c扮r‘um),甲烷八盈菌(M,t八aoo了arei”a),甲 挑珠菌属(阶动aoococc“,)。,十二分:革兰氏阳性球. …     

滇西北兰坪金顶铅锌矿矿区可培养细菌多样性初步研究

目的对兰坪金顶铅锌矿矿区样品中的可培养细菌进行分离并对其多样性进行研究。方法采集云南兰坪金顶铅锌矿矿区土样和矿石样,采用固体肉汤培养基、卯黄培养基及PYGV培养基分离该矿区环境中的可培养细菌,利用16SrRNA基因序列分析构建系统发育树,并统计不同种属细菌的数量,初步评估细菌多样性。结果兰坪金顶铅锌矿矿区环境细菌的主要种群包括放线菌门、变形菌门和厚壁菌门的不同菌属：微球菌属、节杆菌属、假单胞菌属、短波单胞菌属、芽孢杆菌属、类芽孢杆菌属、考克菌属、葡萄球菌属、芽孢八叠球菌及Skermanella属的菌株,其中抗逆性较强的优势菌群为放线菌门的细菌。结论本研究初步证实兰坪金顶铅锌矿矿区可培养细菌种类丰富。     

北极海洋沉积物中锰细菌的分离与系统发育

对中国第二次北极科学考察采集的北极海洋沉积物中的锰细菌进行了筛选、分离和系统发育分析。根据其在筛选平板上菌落的形态学特征,分别从站位P11和S11采集的沉积物中分离到了21株和19株锰细菌。系统发育分析表明,两个站位的锰细菌群落组成有着明显的差别。站位P11分离的可培养锰细菌主要由细菌域（Bacteria）中变形杆菌门的γ-变形杆菌纲（γ-Proteobacteria）和放线菌纲（Actinobacteria）组成,二者分别占86％和14％;γ-变形杆菌纲主要包括嗜冷杆菌属（Psychrobacter）、希瓦氏菌属（Shewanella）、假交替单胞菌属（Pseudoaheromonas）、不动杆菌属（Acinetobacter）、海杆菌属（Marinobacter）,其中以嗜冷杆菌属为主,其比例可达67％。从站位S11分离到的可培养锰细菌主要包括细菌域中变形杆菌门的α-变形杆菌纲（α-Proteobacteria）和γ-变形杆菌纲以及拟杆菌门（Bacteroides）中的黄杆菌纲（Flavobaeteria）;γ-变形杆菌纲主要包括希瓦氏菌属、海单胞菌属（Marinomonas）和交替单胞菌属（Aheromonas）,α-变形杆菌纲主要为鞘氨醇单胞菌属（Sphingomonas）。实验菌株均对Mn^2＋有着较强的抗性,其中以菌株Marinomonas sp．S11-S-4耐受性最高。     

草地贪夜蛾幼虫肠道细菌的分离鉴定及纤维素降解细菌的筛选

【目的】本研究旨在明确草地贪夜蛾Spodopterafrugiperda幼虫肠道可培养细菌组成,筛选纤维素降解细菌。【方法】采用传统细菌培养及16S rDNA分子标记相结合的方法分离鉴定草地贪夜蛾幼虫肠道可培养细菌;采用刚果红染色法筛选纤维素降解细菌,并通过3,5-二硝基水杨酸(DNS)法测定不同pH(5.0-9.0)条件下的纤维素酶活力。【结果】从草地贪夜蛾幼虫中筛选分离出14种肠道细菌菌株,分别隶属放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)等3门11属,即谷氨酸棒杆菌属(Glutamicibacter)、肠球菌属(Enterococcus)、芽胞杆菌属(Bacillus)、葡萄球菌属(Staphylococcus)、摩根菌属(Morganella)、肠杆菌属(Enterobacter)、志贺氏菌属(Shigella)、克洛诺杆菌属(Cronobacter)、克雷伯氏菌属(Klebsiella)、沙雷氏菌属(Serratia)、苍白杆菌属(Ochrobactrum)。2株产纤维素酶细菌隶属厚壁菌门芽胞杆菌属。酶活力测定结果显示:2株纤维素降解细菌的纤维素酶在pH 6.0-8.0均有相对较高的活性,在pH 8.0时,纤维素酶活最高。【结论】草地贪夜蛾幼虫肠道中细菌种类多样,其肠道内存在纤维素降解细菌。在偏碱性条件下,纤维素降解细菌的纤维素酶活力显著高于酸性条件。研究结果丰富了纤维素降解细菌资源,在饲料生产、食品加工、化学能源等方面具有应用前景。此外,草地贪夜蛾作为重大农业害虫,其肠道有益菌群,有望成为新的防治靶标。     

禽源致病性大肠埃希菌安徽分离株I型菌毛pilA基因的序列测定与分析

目的探明大肠埃希菌I型菌毛pilA基因在不同宿主来源菌株间的同源性,为利用Ⅰ型菌毛基因诊断和防治大肠埃希菌病提供理论基础。方法以禽源致病性大肠埃希菌安徽分离株基因组DNA为模板,采用PCR方法扩增Ⅰ型菌毛pilA基因,并进行序列测定与分析。结果 13株不同血清型禽源致病性大肠埃希菌安徽分离株均携带pilA基因,彼此间该基因的核苷酸序列和氨基酸序列同源性分别介于84.9%～99.7%和86.2%～99.2%。pilA基因核苷酸序列在安徽分离株与鸡源参考株、猪源参考株以及人源参考株之间的同源性分别为85.9%～99.7%、85.9%～93.9%和87.5%～100%,氨基酸序列同源性分别为83.1%～99.2%、88.5%～93.8%和90%～100%。系统发育进化树分析显示JD16、JD34、JD11、JD24、YD2、JD8和YD1禽源安徽分离株与人源参考株sPH2的亲缘关系较近,在进化树的同一分支上;GD3、YD5、GD2、YD3、YD5和YD7禽源安徽分离株与鸡源参考株PDI-386和猪源参考株107/86的亲缘关系较近,在进化树中属于同一分支;GD1禽源安徽分离株与鸡源参考株HY1-2和MS2-1的亲缘关系较近,在进化树中属于另一分支。结论大肠埃希菌I型菌毛pilA基因在不同宿主来源菌株及不同血清型菌株之间高度保守,可作为大肠埃希菌病的诊断基因和疫苗候选基因。     

<Emphasis Type="Italic">Delftia</Emphasis> sp. JD2: a potential Cr(VI)-reducing agent with plant growth-promoting activity

A chromium (Cr)-resistant bacterium isolated from soil containing 6,000 mg/kg of Cr was identified based on 16S rRNA gene sequence analysis as Delftia, and designated as JD2. Growth of JD2 was accompanied with reduction of Cr(VI) to Cr(III) in liquid medium initially containing 100 mg/L Cr(VI), the maximum concentration allowing growth. JD2 showed NADH/NADPH-dependent reductase activity associated with the soluble fraction of cells. The results suggest that JD2 might be a good candidate for the treatment of highly Cr(VI)-contaminated water and/or industrial effluents. The isolate produced indole-3-acetic acid in the presence and absence of Cr(VI) and showed free-living nitrogen-fixing activity possibly attributable to a V-nitrogenase. JD2 did not counteract the harmful effect of Cr(VI) during leguminous plant growth and nodulation by rhizobial strains but functioned as a “helper” bacterium to enhance the performance of rhizobial inoculant strains during inoculation of alfalfa and clover (used as model plants to study plant growth-promoting activity) in the absence of Cr(VI).     

Hypothalamic control of body temperature: insights from the past

This essay looks at the historical significance of three APS classic papers that are freely available online: Hammel HT, Hardy JD, and Fusco MM. Thermoregulatory responses to hypothalamic cooling in unanesthetized dogs. Am J Physiol 198: 481-486, 1960 (http://ajplegacy.physiology.org/cgi/reprint/198/3/481). Hammel HT, Jackson DC, Stolwijk JAJ, Hardy JD, and Stromme SB. Temperature regulation by hypothalamic proportional control with an adjustable set point. J Appl Physiol 18: 1146-1154, 1963 (http://jap.physiology.org/cgi/reprint/18/6/1146). Hellstrom B and Hammel HT. Some characteristics of temperature regulation in the unanesthetized dog. Am J Physiol 213: 547-556, 1967 (http://ajplegacy.physiology.org/cgi/reprint/213/2/547).     

Production of excreted human epidermal growth factor (hEGF) by an efficient recombinant Escherichia coli system

Recombinant Escherichia coli JM101 strains harbouring plasmids pWKW2 or lacUV5par8EGF, both encoding human epidermal growth factor (hEGF), were used in fermentations to optimize levels of excreted hEGF. Medium composition, inducer level, growth stage at induction and culture conditions, were optimized with respect to volumetric production of the recombinant protein. MMBL medium, with glucose at 5 g/l and tryptone as nitrogen source, was chosen. Isopropyl-β- -thiogalactopyranoside(IPTG) concentrations of 0.1 mM for E. coli JM101[pWKW2] and 0.2 mM for E. coli K-12 JM101[lacUV5par8EGF], were found to give the best hEGF production levels. The volumetric yields of hEGF were maximal when the cultures were induced in the mid-logarithmic phase. Growth temperature had a significant effect on hEGF yield. A simple continuous fed-batch process for cultivation of E. coli JM101[pWKW2] was developed. The maximum concentration of excreted hEGF attained in continuous fed-batch cultivation was 325 mg/l, as compared to 175 mg/l, in batch cultivation. The hEGF produced from the continuous fed-batch cultivation was substantiated by SDS-PAGE and immunoblotting.     

传染性法氏囊病毒的抗原及分子特征

用鸡胚成纤维细胞对来自野外的 5 个传染性法氏囊病毒株 (IBDV-JD1 、 JD2 、 NB 、 HZ1 、 HZ2) 进行分离,测定理化特性、致病性,同时进行血清亚型测定及 A 片段基因组的克隆分析 . 试验所用 5 个法氏囊组织悬液在鸡胚成纤维细胞盲传 2~14 代后适应细胞并产生细胞病变 . 细胞适应的 IBDV 毒株的理化和形态特征与经典传染性法氏囊病毒株一致 . 除 IBDV-HZ1 、 HZ2 属经典 IBDV 血清型外, IBDV-JD1 、 JD2 和 NB 毒株分属不同的血清亚型 . 人工感染实验结果显示,分离的 IBDV 毒株产生与野外病例相似的临床症状和病变,出现法氏囊滤泡髓质的淋巴细胞变性、坏死和消失 . 基因组序列分析显示, IBDV-NB 毒株 A 片段由 3 264 个核苷酸组成,编码由 145 个氨基酸残基组成的 VP5 和由 1 012 个氨基酸残基组成的多聚蛋白 . 与来自 GenBank 的 IBDV Ⅰ型毒株比较, NB 毒株 A 片段编码的多聚蛋白与 JD1 毒株的同源性最高,达 99.5% , VP2 与 JD1 、 CEF94 、 D78 的同源性为 99.8% , VP3 与 JD1 的同源性为 99.2% , VP4 与 JD1 的同源性为 100% , VP5 与 JD1 , HZ2 , P2 , CEF94 , CT , Cu-1 和 D78 毒株的同源性为 99.3%. NB 毒株 VP2 蛋白的第 253 、 280 、 284 位氨基酸残基与 IBDV 变异毒株和经典毒株一致,但不同于 IBDV 超强毒株 . 这些结果暗示 IBDV 的抗原表位是构象依赖性表位, IBDV 血清亚型的形成与 IBDV 弱毒疫苗病毒株密切相关 .     

Toluene degradation by Pseudomonas putida F1. Nucleotide sequence of the todC1C2BADE genes and their expression in Escherichia coli

The nucleotide sequence of the todC1C2BADE genes which encode the first three enzymes in the catabolism of toluene by Pseudomonas putida F1 was determined. The genes encode the three components of the toluene dioxygenase enzyme system: reductaseTOL (todA), ferredoxinTOL (todB), and the two subunits of the terminal dioxygenase (todC1C2); (+)-cis-(1S, 2R)-dihydroxy-3-methylcyclohexa-3,5-diene dehydrogenase (todD); and 3-methylcatechol 2,3-dioxygenase (todE). Knowledge of the nucleotide sequence of the tod genes was used to construct clones of Escherichia coli JM109 that overproduce toluene dioxygenase (JM109(pDT-601]; toluene dioxygenase and (+)-cis-(1S, 2R)-dihydroxy-3-methylcyclohexa-3,5-diene dehydrogenase (JM109(pDTG602]; and toluene dioxygenase, (+)-cis-(1S, 2R)-dihydroxy-3-methylcyclohexa-3,5-diene dehydrogenase, and 3-methylcatechol 2,3-dioxygenase (JM109(pDTG603]. The overexpression of the tod-C1C2BADE gene products was detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The three E. coli JM109 strains harboring the plasmids pDTG601, pDTG602, and pDTG603, after induction with isopropyl-beta-D-thiogalactopyranoside, oxidized toluene to (+)-cis-(1S, 2R)-dihydroxy-3-methylcyclohexa-3,5-diene, 3-methylcatechol, and 2-hydroxy-6-oxo-2,4-heptadienoate, respectively. The tod-C1C2BAD genes show significant homology to the reported nucleotide sequence for benzene dioxygenase and cis-1,2-dihydroxycyclohexa-3,5-diene dehydrogenase from P. putida 136R-3 (Irie, S., Doi, S., Yorifuji, T., Takagi, M., and Yano, K. (1987) J. Bacteriol. 169, 5174-5179). In addition, significant homology was observed between the nucleotide sequences for the todDE genes and the sequences reported for cis-1,2-dihydroxy-6-phenylcyclohexa-3,5-diene dehydrogenase and 2,3-dihydroxybiphenyl-1,2-dioxygenase from Pseudomonas pseudoalcaligenes KF707 (Furukawa, K., Arimura, N., and Miyazaki, T. (1987) J. Bacteriol. 169, 427-429).     

大肠杆菌腺苷脱氨酶基因的克隆、表达与缺失

利用途径工程的基本原理,拟在大肠杆菌核苷酸代谢途径中构建腺苷（AR）转化为腺苷三磷酸（ATP）的新途径,故需使细胞内的腺苷脱氨酶基因（add）缺失。通过构建大肠杆菌MC4100　DNA的基因文库,筛选得到含腺苷脱氨酶基因的DNA片段。构建表达质粒pBD1和pBD2并实现了表达。在此基础上构建了add基因缺失的带卡那霉素抗性基因的线性52kb DNA分子,同时转化JM83、MC4100、BL21（DE3）。经遗传稳定性实验和DNA分子杂交鉴定,确认得到了来自JM83的两株add基因缺陷株J1和J2。再对菌株J1、pUC18／JM83、pBD1／JM83的细胞粗提液做腺苷脱氨酶的酶活鉴定比较,结果表明则没有腺苷脱氨酶活性,pBD1／JM83有比pUC18／JM83强的腺苷脱氨酶活性。     

Cloning and expression of an agarase gene from a marine bacterium Pseudomonas sp. w7

Two different agarase genes (pSW1, pSW3) were cloned from a marine bacterium Pseudomonas sp. W7 into E. coli JM83 using the multicopy plasmid vector pUC19. Two cloned strains of recombinant E. coli which showed the agarase activity were obtained and were named E. coli JM83/pSW1 and E. coli JM83/pSW3. These strains had the insert fragment of 3.7kb and 3.0kb, respectively. The N-terminal amino acid sequence of the agarase containing the recombinant plasmid pSW3 was determined and the sequence did not show homology to any other known agarases. The optimum pH and temperature of the agarases from the cloned strains, E. coli JM83/pSW1 and pSW3, were 6.0, 7.0 and 30°C, 40°C, respectively.     

Desaturation, dioxygenation, and monooxygenation reactions catalyzed by naphthalene dioxygenase from Pseudomonas sp. strain 9816-4.

The stereospecific oxidation of indan and indene was examined with mutant and recombinant strains expressing naphthalene dioxygenase of Pseudomonas sp. strain 9816-4. Pseudomonas sp. strain 9816/11 and Escherichia coli JM109(DE3)[pDTG141] oxidized indan to (+)-(1S)-indanol, (+)-cis-(1R,2S)-indandiol, (+)-(1S)-indenol, and 1-indanone. The same strains oxidized indene to (+)-cis-(1R,2S)-indandiol and (+)-(1S)-indenol. Purified naphthalene dioxygenase oxidized indan to the same four products formed by strains 9816/11 and JM109(DE3)[pDTG141]. In addition, indene was identified as an intermediate in indan oxidation. The major products formed from indene by purified naphthalene dioxygenase were (+)-(1S)-indenol and (+)-(1R,2S)-indandiol. The results show that naphthalene dioxygenase catalyzes the enantiospecific monooxygenation of indan to (+)-(1S)-indanol and the desaturation of indan to indene, which then serves as a substrate for the formation of (+)-(1R,2S)-indandiol and (+)-(1S)-indenol. The relationship of the desaturase, monooxygenase, and dioxygenase activities of naphthalene dioxygenase is discussed with reference to reactions catalyzed by toluene dioxygenase, plant desaturases, cytochrome P-450, methane monooxygenase, and other bacterial monooxygenases.     

Proposed mechanism of acetate accumulation in two recombinant Escherichia coli strains during high density fermentation

The productivity of Escherichia coli as a producer of recombinant proteins is affected by its metabolic properties, especially by acetate production. Two commercially used E. coli strains, BL21 (lambdaDE3) and JM109, differ significantly in their acetate production during batch fermentation at high initial glucose concentrations. E. coli BL21 grows to an optical density (OD, 600 nm) of 100 and produces no more than 2 g/L acetate, while E. coli JM109 grows to an OD (600 nm) of 80 and produces up to 14 g/L acetate. Even in fed-batch fermentation, when glucose concentration is maintained between 0.5 and 1.0 g/L, JM109 accumulates 4 times more acetate than BL21. To investigate the difference between the two strains, metabolites and enzymes involved in carbon utilization and acetate production were analyzed (isocitrate, ATP, phosphoenolpyruvate, pyruvate, isocitrate lyase, and isocitrate dehydrogenase). The results showed that during batch fermentation isocitrate lyase activity and isocitrate concentration were higher in BL21 than in JM109, while pyruvate concentration was higher in JM109. The activation of the glyoxylate shunt pathway at high glucose concentrations is suggested as a possible explanation for the lower acetate accumulation in E. coli BL21. Metabolic flux analysis of the batch cultures supports the activity of the glyoxylate shunt in E. coli BL21.