海带发酵降解中相关海洋功能菌的分离、鉴定与筛选CSCD

目的从海带养殖环境中筛选有效降解海带的海洋功能菌,对海带进行降解处理,提高利用率,增加海带原料价值。方法采用以果胶或海藻酸钠为唯一碳源的选择性培养基挑选含有果胶酶、褐藻酸裂解酶的菌株;测定海带发酵液中海藻酸含量,复筛降解效果好的单菌及复合菌;16S rDNA测序对菌种进行鉴定。结果使用含10%鲜海带的富集培养基培养48 h,其中降解效果较好的为1-2和3-10菌种的组合,其降解量为95%。结论经上述研究选出有效的降解海带功能菌1-2和3-10,其降解海带效果较好,对海带利用率高。     

海带发酵降解中相关海洋功能菌的 分离、鉴定与筛选

目的 从海带养殖环境中筛选有效降解海带的海洋功能菌,对海带进行降解处理,提高利用率,增加海带原料价值。方法 采用以果胶或海藻酸钠为唯一碳源的选择性培养基挑选含有果胶酶、褐藻酸裂解酶的菌株;测定海带发酵液中海藻酸含量,复筛降解效果好的单菌及复合菌;16S rDNA测序对菌种进行鉴定。结果 使用含10%鲜海带的富集培养基培养48 h,其中降解效果较好的为1-2和3-10菌种的组合,其降解量为95%。结论 经上述研究选出有效的降解海带功能菌1-2和3-10,其降解海带效果较好,对海带利用率高。     

海带藻际微生物抗菌活性及其多样性的初步研究

从浙江台州海域健康海带、病烂海带(Laminaria japonica)及其周围海水中分离纯化海带藻际微生物, 利用双层琼脂扩散法对获得的菌株进行抗菌活性筛选, 比较活性菌株与来源的相关性, 并对具有抗菌活性的菌株进行16S rRNA系统发生学分析。结果显示, 在分离的143株海带藻际微生物中, 有42株细菌具有抗菌活性, 其中来源于健康海带和海水的活性菌株比例(35%和29%)大于来源于病烂海带的细菌(23%)。对其中16株具有广谱抗菌活性的菌株进行的16S rRNA系统发生学分析显示, 分别属于Pseudoalteromonas、Rahnella、Donghaeana、Bacillus和Exiguobacterium 5个属。为从藻际微环境的微生物多样性入手了解海带病烂机制以及寻找新的抗菌药物提供研究材料。       

褐藻表面可培养褐藻酸降解菌的原位筛选

【背景】褐藻酸经酶解后生成的褐藻寡糖具有抗氧化、抗肿瘤、诱导免疫调节、调节植物生长等多元化的生物学功能,在食品、医药领域应用前景广阔。大量筛选褐藻酸降解菌有利于获得新结构、新功能的褐藻寡糖,有利于积极推动寡糖产业进程。【目的】高效筛选褐藻酸降解菌株,发掘具有开发前景的海藻原位微生物资源。【方法】利用褐藻酸唯一碳源培养基对天然铜藻表面微生物进行筛选;革兰氏碘液显色反应指示微生物降解褐藻酸的特性;牛津杯法初步测定产褐藻酸裂解酶菌株的酶活大小。【结果】从铜藻表面共获得81个菌落,经透明圈显色筛选出28株菌,通过16S rRNA基因测序分析得到7株褐藻酸降解菌,分别属于芽孢杆菌属、节杆菌属、德库菌属、短杆菌属和链孢子囊菌属。除芽孢杆菌属外,其余菌属的菌种此前均未被报道过有产褐藻酸裂解酶的能力。进一步分析表明,T-1菌株的产酶能力最强、酶活力最高。【结论】利用革兰氏碘液显色结合牛津杯法筛选到7株产酶菌株,并比较了各菌株的酶活大小,表明该筛选方法简便高效,适合大规模筛选褐藻酸降解菌株。     

一种用途广泛的食品添加剂——褐藻胶

海带是我国海藻养殖的主要品种。褐藻胶以海带为主要生产原料,通常可作为食品的增稠剂、赋形剂、凝胶剂和品质改良剂。一般情况下,其增稠能力是果胶的十倍以上,其价格则只及果胶的1/2—1/3。褐藻胶不但是一种安全的天然食品添加剂,同时对人体还具有整肠作用,并有助于排除人体内积蓄的放射性元素。食品工业应用的褐藻胶主要品种为:褐藻酸钠和褐藻酸丙二酯。这些水溶性褐藻胶产品可以按不同的分子量、含钙量、颗粒状(粒状或     

我国主要河口沉积物中多环芳烃细菌降解及生物修复强化方式的研究进展

河口是海洋及陆地交互作用的集中地带,其生态环境的健康状况对所在地区人类居住及社会经济的可持续发展十分重要。近年来,河口城市的快速发展导致了大量的多环芳烃(polycyclic aromatic hydrocarbons,PAHs)在河口沉积物中积累,持久地影响水生生态系统的健康,其降解与转化逐渐成为近年来的研究热点。本文总结发现,我国主要河口(珠江口、长江口、辽河口、海河口)沉积物中的PAHs降解菌主要分布于假单胞菌门、放线菌门及芽孢杆菌门,其中克雷伯氏菌属、芽孢杆菌属及假单胞菌属报道较多。在河口沉积物中,PAHs的细菌降解主要是通过低效率的厌氧降解途径。低氧、高盐度是PAHs细菌降解的不利条件,温度与pH值的变化也为实地生物修复的应用效率带来了不确定性。表面活性剂、营养物与外源电子受体的添加以及共代谢作用均可促进沉积物细菌对PAHs的降解。目前多数研究以实验室规模开展,而河口沉积物生境复杂,建议未来针对河口沉积物的环境特点进行PAHs降解功能菌株种质资源的挖掘,并根据实际情况灵活制定强化策略。本综述为进一步从我国主要河口沉积物中筛选PAHs高效降解菌及其利用提供了思路与参考。     

坛紫菜养殖周期中的藻际微生物多样性

摘要:【目的】坛紫菜是我国江浙海区栽培地主要经济藻类。观察紫菜养殖过程中藻际微生物的群落特点及变化,研究藻际环境中的微生物因素在紫菜栽培中的作用,为保证紫菜健康生长及病害防治提供理论与实验基础。【方法】采用传统纯培方法和PCR-DGGE 技术分离归类坛紫菜养殖周期中的藻际微生物,并利用16SrDNA (细菌)和18S rDNA(真菌)序列测定及在线BLAST比对鉴定到属,比较分析不同生长阶段、不同养殖海区及养殖过程的坛紫菜藻际微生物的多样性特点。【结果】在坛紫菜养殖过程中总共分离到467株细 菌,共41个属。分类结果显示藻际细菌归属于变形菌门(Alphaproteobacteria和Gammaproteobacteria)、放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes),优势菌群为α-变形菌纲和γ-变形菌纲。分离到55株真菌,共15个属。分类结果显示绝大多数真菌归属于子囊菌门(Ascomycota),仅1株归属于担子菌门(Basidiomycota)伞菌纲(Agaricomycetes)。细菌多样性大于真菌。坛紫菜藻际细菌有19个特异菌属,对照海水细菌有13个特异菌属;从丝状体中分离到大部分真菌和放线菌,坛紫菜养殖丝状体和不同叶状体养殖阶段的藻际微生物类别差异明显。在分离的坛紫菜藻际微生物中发现了与引起细菌性红烂病的海科贝特菌(Cobetia marina)、引起白斑病的紫菜茎点菌(Phoma porphyrae)高度相似的菌株,以及与典型的腐霉如镰孢霉菌(Fusarium sp.)和曲霉(Aspergillus sp.)高度相似的菌株。【结论】坛紫菜养殖过程中藻际微生物的多样性受到紫菜生长形态、养殖时间及养殖环境等因素的影响。在藻际微生物中发现与紫菜致病菌高度相似的微生物,作为潜在致病微生物应得到重视。     

草鱼（Ctenopharyngodon idellus）烂鳃病的研究——Ⅰ．细菌性病原的研究

本文主要是报导1972年从患细菌性烂鳃的草鱼和其他色的鳃上分离到的病原粘细菌。通过多次人工感染(包括再分离和再感染),证明G4菌株是草鱼细菌性烂鳃病的病原菌,它能引起草、鳙、鲢、草鳙杂种、团头鲂、鲤等色的烂鳃病。对G4菌株的菌体、子实体、小孢子的形态、培养特性、生理生化特性作了较详细的观察和试验;根据其特征,定名为色害粘球菌——新种(Myxococcus piscicola Lu,Nie ＆ Ko,sp.nov）。较详细地观察了G4菌株在胰胨液体培养中的群集习性,“柱子”形成、繁殖散发和衰老死亡的全过程。认为“柱子”形成是G4菌株,也可能是所有色类寄生粘细菌所共有的一种运动、繁殖的表现形式,它是不会转化为真正的子实体的。草鱼细菌性烂鳃病是危害很大的鱼病之一。其病原菌分离的成功,对有效地防治该病,控制该病的流行,提供了有利条件,同时也丰富了研究鱼类寄生粘细菌的学术内容。     

草鱼(Ctenopharyngodon idellus)烂鳃病的研究 Ⅰ.细菌性病原的研究

本文主要是报导1972年从患细菌性烂鳃的草鱼和其他鱼的鳃上分离到的病原粘细菌。通过多次人工感染(包括再分离和再感染),证明G4菌株是草鱼细菌性烂鳃病的病原菌,它能引起草、鳙、鲢、草鳙杂种、团头鲂、鲤等鱼的烂鳃病。对G4菌株的菌体、子实体、小孢子的形态、培养特性、生理生化特性作了较详细的观察和试验;根据其特征,定名为鱼害粘球菌——新种(Myxococcus piscicola Lu,Nie Ko,sp.nov.)。较详细地观察了G4菌株在胰胨液体培养中的群集习性,“柱子”形成、繁殖散发和衰老死亡的全过程。认为“柱子”形成是G4菌株,也可能是所有鱼类寄生粘细菌所共有的一种运动、繁殖的表现形式,它是不会转化为真正的子实体的。草鱼细菌性烂鳃病是危害很大的鱼病之一。其病原菌分离的成功,对有效地防治该病,控制该病的流行,提供了有利条件,同时也丰富了研究鱼类寄生粘细菌的学术内容。       

鲍氏不动杆菌——鳜鱼暴发性死亡的新病原

１９９５年广东某地人工养殖的鳜鱼暴发传染病,大量病鱼急性死亡,引致严重经济损失,本试验从已接种嗜水气单胞菌和柱状噬纤维菌疫苗的病于脏器中分离到一种细菌,经腹腔注射和腮部接种人工感染健康鳜鱼及罗非鱼,均复制出与自然发病相似的病例,主要特点为肝脏严重变性,从上述人工感染的病鱼体内再次分离与自然发病相似的病例,主要特点为肝脏严重变性,从上述人工感染的病鱼体内再次分离到与自然发病相同的细菌。该菌为革兰氏阴     

Evasion of Legionella pneumophila from the bactericidal system by reactive oxygen species (ROS) in macrophages

We demonstrated that the production of reactive oxygen species (ROS) by U937 macrophage-like cells was suppressed upon infection with a wild type Legionella pneumophila strain, whereas such suppression was not observed in the case of infection with intracellular growth-deficient mutants. This was supported not only by measuring ROS released into the supernatants of cell cultures by chemiluminescence assaying but also by detecting intracellular ROS with a fluorescent probe, 2-[6-(4'-amino)phenoxy-3H-xanthen-3-on-9-yl]benzoic acid (APF), under a confocal laser scanning microscope. Furthermore, more than 60% of the phagosomes containing intracellular growth-deficient mutants were colocalized with p47(phox), which is the cytosolic subunit of NADPH oxidase, consistently throughout the observation period in an early stage of bacterial infection. In contrast, the colocalization of p47(phox) was suppressed after infection with the wild type strain. These results suggest that the interference with ROS production by U937 cells infected with wild type L. pneumophila is due to a failure of NADPH oxidase activation through inhibition of p47(phox) recruitment to phagosomes harboring bacteria. The results also highlighted the difference in the nature of phagosomes between ones harboring the wild type and ones the intracellular growth-deficient strains.     

Differential protein expression in Colletotrichum acutatum: changes associated with reactive oxygen species and nitrogen starvation implicated in pathogenicity on strawberry

The cellular outcome of changes in nitrogen availability in the context of development and early stages of pathogenicity was studied by quantitative analysis of two-dimensional gel electrophoresis of Colletotrichum acutatum infecting strawberry. Significant alterations occurred in the abundance of proteins synthesized during appressorium formation under nitrogen-limiting conditions compared with a complete nutrient supply. Proteins that were up- or down-regulated were involved in energy metabolism, nitrogen and amino acid metabolism, protein synthesis and degradation, response to stress and reactive oxygen scavenging. Members belonging to the reactive oxygen species (ROS) scavenger machinery, superoxide dismutase and glutathione peroxidase, were up-regulated at the appressorium formation stage, as well as under nitrogen-limiting conditions relative to growth with a complete nutrient supply, whereas abundance of bifunctional catalase was up-regulated predominantly at the appressorium formation stage. Fungal ROS were detected within germinating conidia during host pre-penetration, penetration and colonization stages, accompanied by plant ROS, which were abundant in the apoplastic space. Application of exogenous antioxidants quenched ROS production and reduced the frequency of appressorium formation. Up-regulation in metabolic activity was detected during appressorium formation and nutrient deficiency compared with growth under complete nutrient supply. Enhanced levels of proteins related to the glyoxylate cycle and lipid metabolism (malate dehydrogenase, formate dehydrogenase and acetyl-CoA acetyltransferase) were observed at the appressorium formation stage, in contrast to down-regulation of isocitrate dehydrogenase. The present study demonstrates that appressoria formation processes, occurring under nutritional deprivation, are accompanied by metabolic shifts, and that ROS production is an early fungal response that may modulate initial stages of pathogen development.     

Horizontal gene transfer in fungi

Reactive oxygen species (ROS) are a key feature of plant (and animal) defences against invading pathogens. As a result, plant pathogens must be able to either prevent their production or tolerate high concentrations of these highly reactive chemicals. In this review, we focus on plant pathogenic bacteria of the genus Pseudomonas and the ways in which they overcome the challenges posed by ROS. We also explore the ways in which pseudomonads may exploit plant ROS generation for their own purposes and even produce ROS directly as part of their infection mechanisms.     

Production of reactive oxygen species (ROS) by various marine fish species during the larval stage

Previous studies have indicated that the devil stinger produces reactive oxygen species (ROS) during early development from fertilized egg to larva. To determine whether ROS generation is a common feature in marine fish species, we conducted chemiluminescence analysis using ROS specific probe (L012) on larvae of six marine fish species. Marbled rockfish, black rockfish, and devil stinger showed higher levels of chemiluminescence response (CR), whereas the levels of CR of sevenband grouper, tiger puffer, and red seabream were fairly lower. These CRs were inhibited by the addition of superoxide dismutase. Hypersensitive photon-counting microscopic observation of black rockfish suggested that ROS production was concentrated in the head area. Our results suggest that the larvae of these six marine fishes produce ROS to considerably different extents depending on species, and that rockfish species, belonging to ovoviviparous fish, tend to produce much higher levels of ROS especially at the later larval stage.     

Early Archean origin of Photosystem II

Photosystem II is a photochemical reaction center that catalyzes the light‐driven oxidation of water to molecular oxygen. Water oxidation is the distinctive photochemical reaction that permitted the evolution of oxygenic photosynthesis and the eventual rise of eukaryotes. At what point during the history of life an ancestral photosystem evolved the capacity to oxidize water still remains unknown. Here, we study the evolution of the core reaction center proteins of Photosystem II using sequence and structural comparisons in combination with Bayesian relaxed molecular clocks. Our results indicate that a homodimeric photosystem with sufficient oxidizing power to split water had already appeared in the early Archean about a billion years before the most recent common ancestor of all described Cyanobacteria capable of oxygenic photosynthesis, and well before the diversification of some of the known groups of anoxygenic photosynthetic bacteria. Based on a structural and functional rationale, we hypothesize that this early Archean photosystem was capable of water oxidation to oxygen and had already evolved protection mechanisms against the formation of reactive oxygen species. This would place primordial forms of oxygenic photosynthesis at a very early stage in the evolutionary history of life.     

Reactive oxygen species modulate Anopheles gambiae immunity against bacteria and Plasmodium

The involvement of reactive oxygen species (ROS) in mosquito immunity against bacteria and Plasmodium was investigated in the malaria vector Anopheles gambiae. Strains of An. gambiae with higher systemic levels of ROS survive a bacterial challenge better, whereas reduction of ROS by dietary administration of antioxidants significantly decreases survival, indicating that ROS are required to mount effective antibacterial responses. Expression of several ROS detoxification enzymes increases in the midgut and fat body after a blood meal. Furthermore, expression of several of these enzymes increases to even higher levels when mosquitoes are fed a Plasmodium berghei-infected meal, indicating that the oxidative stress after a blood meal is exacerbated by Plasmodium infection. Paradoxically, a complete lack of induction of catalase mRNA and lower catalase activity were observed in P. berghei-infected midguts. This suppression of midgut catalase expression is a specific response to ookinete midgut invasion and is expected to lead to higher local levels of hydrogen peroxide. Further reduction of catalase expression by double-stranded RNA-mediated gene silencing promoted parasite clearance by a lytic mechanism and reduced infection significantly. High mosquito mortality is often observed after P. berghei infection. Death appears to result in part from excess production of ROS, as mortality can be decreased by oral administration of uric acid, a strong antioxidant. We conclude that ROS modulate An. gambiae immunity and that the mosquito response to P. berghei involves a local reduction of detoxification of hydrogen peroxide in the midgut that contributes to limit Plasmodium infection through a lytic mechanism.     

Streptococcus sanguinis induces foam cell formation and cell death of macrophages in association with production of reactive oxygen species

Streptococcus sanguinis, a normal inhabitant of the human oral cavity, is a common streptococcal species implicated in infective endocarditis. Herein, we investigated the effects of infection with S. sanguinis on foam cell formation and cell death of macrophages. Infection with S. sanguinis stimulated foam cell formation of THP-1, a human macrophage cell line. At a multiplicity of infection >100, S. sanguinis-induced cell death of the macrophages. Viable bacterial infection was required to trigger cell death because heat-inactivated S. sanguinis did not induce cell death. The production of cytokines interleukin-1β and tumor necrosis factor-α from macrophages was also stimulated during bacterial infection. Inhibition of the production of reactive oxygen species (ROS) resulted in reduced cell death, suggesting an association of ROS with cell death. Furthermore, S. sanguinis-induced cell death appeared to be independent of activation of inflammasomes, because cleavage of procaspase-1 was not evident in infected macrophages.     

Reactive oxygen and nitrogen species are involved in sorbitol-induced apoptosis of human erithroleukaemia cells K562

In this study, we found that production of both reactive oxygen (ROS) and nitrogen (RNS) species is a very early event related to treatment with hyperosmotic concentration of sorbitol. The production of nitric oxide (NO) was paralleled by the increase of the mRNA and protein level of the inducible form of the nitric oxide synthase (iNOS). ROS and RNS enhancement, process concomitant to the failure of mitochondrial trans-membrane potential (ΔΨ), was necessary for the induction of apoptosis as demonstrated by the protection against sorbitol-mediated toxicity observed after treatment with ROS scavengers or NOS inhibitors. The synergistic action of ROS and RNS was finally demonstrated by pre-treatment with rosmarinic acid that, by powerfully buffering both these species, prevents impairment of ΔΨ and cell death. Overall results suggest that the occurrence of apoptosis upon sorbitol treatment is an event mediated by oxidative/nitrosative stress rather than a canonical hyperosmotic shock.