Simulation of the impacts of diagenesis or low-grade metamorphism on neutrophilic microaerobic Fe(II)-oxidizing biofilm     

LI Jun  LI YiLiang 《中国科学:地球科学(英文版)》2014,57(5):1021-1029

The microaerobic iron-oxidizing bacteria in circumneutral environment produce extracellular polymeric substances(EPS)with unique morphologic features,such as stalks or sheaths,which can be regarded as geobiological signatures.The Archean and early Palaeoproterozoic oceans were anoxic with high soluble Fe(II)that were suggested to have been oxidized through the metabolism of Fe(II)-oxidizing bacteria.The precursor of the ultrafine hematite in banded iron formation(BIF),e.g.,ferrihydrite,was suggested to be the mineral record of microbial Fe(II)-oxidation at that time.However,both the biological materials and primary iron minerals were prone to being altered by diagenetic or low-grade metamorphic processes.This makes it difficult to interpret the genesis of Precambrian BIFs.Here,we report experimental simulation on the effects of diagenesis or low-grade metamorphism on neutrophilic microaerobic Fe(II)-oxidizing bacteria and their biomass.Stalks,sheaths,and iron oxide spheroidal aggregates are partially preserved after the 100 MPa/300°C treatments,which indicates the mixed organic matters and iron oxides could survive the diagenetic or low-grade metamorphic processes.Some organic-mineral mixing structures carry information on microbial processes,though they appear similar to pseudomorphs of fossilized bacteria.  相似文献   

A polysaccharide-degrading marine bacterium Flammeovirga sp. MY04 and its extracellular agarase system     

Wenjun Han  Jingyan Gu  Qiujie Yan  Jungang Li  Zhihong Wu  Qianqun Gu  Yuezhong Li 《中国海洋大学学报(英文版)》2012,11(3):375-382

Bacteria of the genus Flammeovirga can digest complex polysaccharides (CPs), but no details have been reported regarding the CP depolymerases of these bacteria. MY04, an agarolytic marine bacterium isolated from coastal sediments, has been identified as a new member of the genus Flammeovirga. The MY04 strain is able to utilize multiple CPs as a sole carbon source and grows well on agarose, mannan, or xylan. This strain produces high concentrations of extracellular proteins (490 mg L-1 ± 18.2 mg L-1 liquid culture) that exhibit efficient and extensive degradation activities on various polysaccharides, especially agarose. These proteins have an activity of 310 U mg-1 ± 9.6 U mg-1 proteins. The extracellular agarase system (EAS) in the crude extracellular enzymes contains at least four agarose depolymerases, which are with molecular masses of approximately 30-70 kDa. The EAS is stable at a wide range of pH values (6.0-11.0), temperatures (0-50℃), and sodium chloride (NaCl) concentrations (0- 0.9 mol L-1). Two major degradation products generated from agarose by the EAS are identified to be neoagarotetraose and neoagarohexaose, suggesting that β-agarases are the major constituents of the MY04 EAS. These results suggest that the Flammeovirga strain MY04 and its polysac-charide-degradation system hold great promise in industrial applications.  相似文献   

A Polysaccharide-Degrading Marine Bacterium Flammeovirga sp.MY04 and Its Extracellular Agarase System     

HAN Wenjun  GU Jingyan  YAN Qiujie  LI Jungang  WU Zhihong  GU Qianqun  LI Yuezhong 《青岛海洋大学学报(英文版)》2012,(3):375-382

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具有多种胞外酶的对虾肠道黏附菌的分离和鉴定     

刘慧玲  罗鹏  杨世平  李广聪  莫嘉文  王蔚 《广东海洋大学学报》2012,(3):1-5

用对虾饲料培养基从健康凡纳滨对虾肠道分离出500株黏附细菌,以产淀粉酶、脂肪酶和蛋白酶能力为指标,筛选出产该3种消化酶的细菌90株,占总菌株的18%.对其中生长较快的69株进行16S rDNA 基因测序,确定其分类地位.结果显示,69株菌分别属于不动杆菌属(Acinetobacter)、芽孢杆菌属(Bacillus)、葡萄球菌属(Staphylococcus)、假交替单胞菌属(Pseudoalteromonas)、气单胞菌属(Aeromonas)、嗜盐单胞菌属(Halomonas)、利斯顿氏菌属(Listonella)、莫拉氏菌属(Moraxella)等,其中数量最多是芽胞杆菌属,占鉴定细菌总数的53.62%,数量最少是气单胞菌属和嗜盐单胞菌属,均占鉴定细菌总数的2.90%.表明对虾肠道黏附菌群中具有较多能分泌多种消化酶的细菌,可进一步开发为促进对虾消化功能的益生菌  相似文献   

Iron-stimulated growth and microcystin production of Microcystis novacekii UAM 250     

Hongli Li  Tom Murphy  Jay Guo  Tanya Parr  Czesia Nalewajko 《Limnologica》2009,39(3):255-259

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PROPERTIES OF PROTEOLYTIC TOXIN OF VIBRIO ANGUILLARUM FROM DISEASED FLOUNDER   总被引：3，自引：0，他引：3  

莫照兰  陈师勇  张培军 《中国海洋湖沼学报》2002,20(4):316-322

Extracellular products(ECP)produced by Vibrio anguillarum strain M3 originally isolated from diseased flounder(Paralichthys olivaceus)were prepared.ECP of M3 showed gelatinase,casinase,amylase and haemolytic activity on agarose plates.High protease activity against azocasin was detected.Bacterium M3 showed highest growth and protease activity at 25℃。The Protease present in ECP showed maximal activity at pH 8 and 55℃；was completely inactivated by application of 80℃ heat for 30 min;was completely inhibited by EDTA and HgCl2,and was partially inhibited by PMSF,SDS,MnCl2 and iodoacetic acid;but not inhibited by CaCl2 and MgCl2.The ECP was toxic to flounder fish at LD50 values of 3.1 μg protein/g body weight.The addition of HgCl2 and application of heat at 50℃ decreased the lethal toxicity of ECP.When heated at 100℃,ECP lethality to flounder was completely in-hibited.After intramuscular injection of ECP into flounder,it showed evident histopathological changes including necrosis of muscle,extensive deposition of haemosiderin in the spleen,dilated bolld vessels congested with numerous lymphocytes in the liver.These results showed that ECP protease was a lethal factor produced by the baterium V.anguillarum M3.  相似文献   

石墨对污泥中厌氧微生物代谢产物及其性能的影响     

朱梦扬  李青  王进  陈天虎  周跃飞  彭书传 《岩石矿物学杂志》2016,35(4):721-728

矿物材料对废水厌氧处理及厌氧污泥改性具有十分重要的作用,而微生物代谢产物是生物处理系统的重要组分,在提高污染物去除率和甲烷产量等方面也起到非常重要的作用。本研究对矿物材料石墨和厌氧微生物共存体系内溶解性微生物产物(soluble microbial product,SMP)和胞外聚合物(extracellular polymeric substances,EPS)进行了分析表征。结果表明,石墨对EPS和SMP的组成和含量影响显著,主要是由于石墨的吸附作用及其对石墨颗粒的环境毒性所致。红外光谱分析表明,添加石墨体系内SMP与EPS的基团种类并未发生明显改变,但含量有所改变。三维荧光分析结果显示,SMP的主要荧光类物质为色氨酸类似物和腐殖质(辅酶NADH),而EPS的主要荧光类物质为色氨酸类似物和腐殖酸,石墨能明显降低色氨酸类似物及腐殖酸类物质的产生。石墨会减弱微生物的相对疏水性,提高表面自由能,有利于微生物团聚体的形成。  相似文献   

Mg²⁺、Mn²⁺对波吉卵囊藻生长的影响     

张慧  刘锦上  黄翔鹄 《广东海洋大学学报》2021,(2)

【目的】研究Mg²⁺、Mn²⁺对波吉卵囊藻生长和多糖代谢的影响。【方法】取蒸馏水培养数日后的波吉卵囊藻液接入以f/2培养液的配方为基础的新鲜培养液中,Mg²⁺浓度梯度分别设置为0、1、2、4、8 mg/L,Mn²⁺浓度梯度分别设置为0、0.005、0.050、0.500、5.000 mg/L,实验周期为10 d。【结果与结论】不同浓度Mg²⁺、Mn²⁺对波吉卵囊藻的生长有显著性影响,当Mg²⁺质量浓度为2 mg/L时,波吉卵囊藻的相对增长率、色素蛋白含量均出现最大值,显著高于Mg²⁺添加量为0、4和8 mg/L的组(P<0.05),当Mn²⁺质量浓度为0.005 mg/L时,波吉卵囊藻相对增长率、色素蛋白含量均出现最大值,显著高于Mn²⁺添加量0、0.050、0.500和5.000 mg/L组(P<0.05)。不同浓度Mg²⁺、Mn²⁺对波吉卵囊藻胞外多糖含量有显著影响(P<0.05),当Mg²⁺质量浓度>2 mg/L、Mn²⁺质量浓度>0.005 mg/L时,波吉卵囊藻生长均受到胁迫,其胞外多糖合成量明显增加,以保护藻体不受危害;当Mg²⁺质量浓度为8 mg/L、Mn²⁺质量浓度为5.000 mg/L时,波吉卵囊藻胞外多糖含量分别为对照组的2.43和3.36倍。  相似文献   

溶藻弧菌胞外产物注射赤点石斑鱼后的组织病理学观察     

左凤琴  简纪常  吴灶和 《广东海洋大学学报》2006,26(3):13-16

在注射溶藻弧菌胞外产物(ECP)48 h后,石斑鱼Epinephelus akaara出现死亡,临床症状表现为:运动迟缓,体色变深,腹部膨大,腹腔有明显的积水,肝脏出血有花斑,肾脏和脾脏肿大。病理组织切片观察发现:肝细胞坏死,解体,界限模糊,细胞核变形、裂解甚至消失;肝脏出血,肝索中有红细胞浸润,有的红细胞变形甚至破裂;肾小管上皮细胞脱落、坏死;肠粘膜上皮细胞脱落、坏死,微绒毛不整齐,模糊不清,脱落;脾窦和脾索不清晰,分界不清,且在脾窦和脾索中分布着大量的、形态不规则的红细胞。此外,还发现在肝脏、脾脏、肾脏、肠壁肌层、心肌和鳃等组织中存在一种相同结构,该结构有平滑肌环绕,管腔内壁衬以扁平上皮细胞,管腔中含有一团染成紫红色的物质,经推断为小动脉透明样变性,而在正常的组织切片中,均无此结构。  相似文献   

海豚链球菌(Streptococcus iniae)胞外产物对斑点叉尾鮰(Ictalurus punctatus)的致病性     

陈德芳  汪开毓  王均  耿毅  黄凌远  胡迪  景简飞 《海洋与湖沼》2013,44(2):326-331

采用硫酸铵盐析法提取海豚链球菌DGX07菌株的胞外产物(ECPs),通过平板扩散法对其主要酶成分进行初步研究,对酶热稳定和溶血活性进行测定;并对腹腔注射接种海豚链球菌(S.iniae)胞外产物的斑点叉尾进行组织病理学观察。结果显示,菌株胞外产物具有蛋白酶、DNA酶和溶血活性;DNA酶表现出一定的热稳定性,而蛋白酶和溶血活性在80℃或100℃作用10min均丧失;胞外产物对人(O型)、兔、斑点叉尾、草鱼、鲤鱼、鲫鱼、黄颡鱼和长吻的红细胞均表现出不同程度的溶血活性;人工感染试验显示,0.222mg/ml的S.iniaeECPs对斑点叉尾具有明显的致病性,死亡率达100%;临床特点表现为:游动缓慢、体表褪色、鳍条边缘褪色,内脏器官肿胀并伴有腹水;组织学病变主要表现为全身性多组织、器官炎性水肿,伴有组织内出血,实质细胞变性和坏死,尤以肝胰脏、脾脏、肾脏、肠道和心脏的损伤最为严重。试验结果表明海豚链球菌胞外产物含有多种毒力因子,与该菌的致病性密切相关。  相似文献