草鱼肠道黏膜厌氧细菌的分离与鉴定

研究以草鱼(Ctenopharyngodon idellus)为实验对象, 运用厌氧培养的方法, 研究了饥饿状态下草鱼肠道黏膜固有微生物的类群及其在不同肠段的分布。实验结果显示草鱼前肠、中肠与后肠中细菌的数量分别是3.17×103、1.63×104和1.79×107 cfu/g。研究共分离到274株单菌落, 经16S rRNA鉴定, 分别属于拟杆菌属(Bacteroides spp.)、鲸杆菌属(Cetobacterium spp.)、梭形杆菌属(Fusobacterium spp.)、气单胞菌属(Aeromonas spp.)、希瓦氏菌属(Shewanella spp.)、芽孢杆菌属(Bacillus spp.)、泛菌属(Pantoea spp.)和柠檬酸杆菌属(Citrobacter spp.)8个种类, 其中专性厌氧细菌的数量占9.1%, 兼性厌氧细菌的数量占90.9%。进一步分析发现, 前肠中只分离到兼性厌氧细菌, 中肠与后肠专性厌氧细菌和兼性厌氧细菌都有分布。专性厌氧细菌Bacteroides paurosaccharolyticus和Bacteroides luti在中肠与后肠都有分布, 而Cetobacterium somerae和Fusobacterium ulcerans只在后肠有发现。兼性厌氧细菌是草鱼肠道黏膜的优势菌群, 其中嗜水气单胞菌Aeromonas hydrophila占73.7%。草鱼肠道不同部位固有厌氧微生物组成存在差异, 细菌数量也明显不同, 后肠中具有更高的细菌丰度和多样性。     

草鱼肠道纤维素降解细菌的分离与鉴定

为更好地弄清草鱼（Ctenopharyngodon idella）肠道纤维素降解细菌的种类,采用羧甲基纤维素（CMC）作为唯一碳源的选择性培养基,分别从草鱼肠道内容物和肠道黏膜中分离到了40株产纤维素酶细菌。16S rRNA基因序列的分析结果显示,大多数产纤维素酶细菌为气单胞菌属（Aeromonas）的种类,其次为肠杆菌属（Enterobacter）的细菌以及未经分离纯培养的细菌（Uncultured bacterium）。进一步研究细菌产纤维素酶能力发现,纤维素酶活性显著性高于其他菌株的分别是A. veronii MC2、A. veronii BC6、肠杆菌科（Enterobacteriaceae）中一种未经分离纯培养的细菌BM3（Uncultured bacterium BM3）和A. jandaei HC9。草鱼肠道中简答气单胞菌（A. jandaei）、类志贺邻单胞菌（Plesiomonas shigelloides）、阴沟肠杆菌（E. cloacae）以及产气肠杆菌（E. aerogenes）是被作为产纤维素酶细菌的首次报道。       

Effects of three strains of intestinal autochthonous bacteria and their extracellular products on the immune response and disease resistance of common carp,Cyprinus carpio

The study isolated three strains of intestinal autochthonous bacteria Aeromonas veronii BA-1, Vibrio lentus BA-2, and Flavobacterium sasangense BA-3 from the intestinal tract of the common carp (Cyprinus carpio). To reveal the effects of these three strains of bacteria on the innate immunity of carp, the lysozyme, complement C3, total serum protein, albumin and globulin levels, respiratory burst activity, phagocytic activity by blood leucocytes and the expression of IL-1b, lysozyme-C, and TNF-α were examined after feeding with seven different diets for up to 28 days. Also the survival of carp against Aeromonas hydrophila was challenged for 14 days. The carp were fed seven different diets: one control, three diets supplemented with 1 × 10⁸ cell g⁻¹ of carp intestinal bacteria BA-1 (Group D-I), BA-2 (Group D-II) and BA-3 (Group D-III), and three diets supplemented with extracellular products FA-1 (Group E-I), FA-2 (Group E-II) and FA-3 (Group E-III) which were corresponding to the strains BA-1, BA-2, and BA-3, respectively, up to 28 days. For groups D-I, D-III, E-I and E-III, the innate immune parameters of carp were significantly increased, the expression of three immune-related genes in blood was significantly up-regulated examined during 7, 14, and 21 days of feeding, and the survival rate was improved. The study indicates that the two isolated intestinal autochthonous bacteria A. veronii BA-1 and F. sasangense BA-3 could positively influence immune response and enhance disease resistance of carp against A. hydrophila infection.     

Phylogenetic analysis and in situ identification of the intestinal microbial community of rainbow trout (Oncorhynchus mykiss, Walbaum)

AIMS: To identify the dominant culturable and nonculturable microbiota of rainbow trout intestine. METHODS AND RESULTS: Microbial density of rainbow trout intestine was estimated by direct microscopic counts (4',6-diamidino-2-phenylindole, DAPI) and by culturing on tryptone soya agar (TSA). Differential gradient gel electrophoresis analysis of bacterial DNA from intestinal samples, re-amplification of bands and sequence analysis was used to identify the bacteria that dominated samples where aerobic counts were < or =2% of the DAPI counts. 16S rDNA gene sequences of 146 bacterial isolates and three sequences of uncultured bacteria were identified. A set of oligonucleotide probes was constructed and used to detect and enumerate the bacterial community structure of the gastrointestinal tract of rainbow trout by fluorescence in situ hybridization (FISH). Members of the gamma subclass of Proteobacteria (mainly Aeromonas and Enterobacteriaceae) dominated the bacterial population structure. Acinetobacter, Pseudomonas, Shewanella, Plesiomonas and Proteus were also identified together with isolates belonging to the beta subclass of Proteobacteria and Gram-positive bacteria with high and low DNA G + C content. In most samples, the aerobic count (on TSA) was 50-90% of the direct (DAPI) count. A bacterium representing a previously unknown phylogenetic lineage with only 89% 16S rRNA gene sequence similarity to Anaerofilum pentosovorans was detected in intestinal samples where aerobic counts were < or =2% of direct (DAPI) counts. Ten to 75% of the microbial population in samples with low aerobic counts hybridized (FISH) with a probe constructed against this not-yet cultured bacterium. CONCLUSIONS: Proteobacteria belonging to the gamma subclass dominated the intestinal microbiota of rainbow trout. However, in some samples the microflora was dominated by uncultivated, presumed anaerobic, micro-organisms. The bacterial population structure of rainbow trout intestine, as well as total bacterial counts, varied from fish to fish. SIGNIFICANCE AND IMPACT OF THE STUDY: Good correlation was seen between cultivation results and in situ analysis, however, a molecular approach was crucial for the identification of organisms uncultivated on TSA.     

OmpA is an adhesion factor of Aeromonas veronii, an optimistic pathogen that habituates in carp intestinal tract

Aims: In the present study, we focused on one of the Aeromonas veronii isolates that exhibited marked adhesion onto carp intestine and studied its membrane-associated proteins for their possible involvement in mucosal adhesion. Methods and Results: We isolated a strain of Aer. veronii (CWP11) that exhibited a high degree of temperature-dependent adhesion activity onto carp intestinal tract and studied its adhesion factor. A proteomic analysis of the membrane-associated fraction showed the presence of multiple proteins that were specifically expressed in CWP11 cells cultured at 25°C. Of these, a 30 kDa protein was identified to be OmpA by a mass fingerprint analysis. Cloning and nucleotide sequencing of the ompA region of CWP11 revealed the presence of two tandem ompA homologues (ompAI-ompAII). Escherichia coli that expressed either OmpAI or OmpAII exhibited marked adhesion onto carp intestinal surface. Disruption of ompAI by a homologous recombination technique resulted in marked reduction of the adhesion activity in CWP11. Conclusion: The OmpA homologue plays an important role in the adhesion of the Aer. veronii strain onto the surface of intestinal tract. Significance and Impact of the Study: We successfully identified an OmpA homologue to be an adhesion factor of Aer. veronii, an optimistic pathogen that habituates in carp intestinal tract.     

Genetic heterogeneity and functional properties of intestinal bifidobacteria

AIMS: The aim of the present study was to compare several molecular methods for the identification and genotyping of bifidobacteria, and further to investigate genetic heterogeneity and functional properties of bifidobacterial isolates from intestinal samples of Finnish adult subjects. METHODS AND RESULTS: A total of 153 intestinal bifidobacterial isolates were included in initial screening and 34 isolates were further characterized. Identification results obtained with PCR-ELISA and ribotyping were well in accordance with each other, while randomly amplified polymorphic DNA (RAPD) gave tentative identification only to Bifidobacterium bifidum and to 65% of the B. longum isolates. The most commonly detected species were B. longum biotype longum followed by B. adolescentis and B. bifidum. In addition, B. animalis (lactis), B. angulatum and B. pseudocatenulatum were found. Ribotyping and pulsed-field gel electrophoresis (PFGE) proved to be discriminatory methods for bifidobacteria, but also RAPD revealed intraspecies heterogeneity. Besides two B. animalis (lactis) isolates with very close similarity to a commercially available probiotic strain, none of the intestinal isolates showed optimal survival in all tolerance (acid, bile and oxygen) or growth performance tests. CONCLUSIONS: Several species/strains of bifidobacteria simultaneously colonize the gastrointestinal tract of healthy Finnish adults and intestinal Bifidobacterium isolates were genetically heterogeneous. Functional properties of bifidobacteria were strain-dependent. SIGNIFICANCE AND IMPACT OF THE STUDY: Applicability of ribotyping with the automated RiboPrinter System for identification and genotyping of bifidobacteria was shown in the present study.     

Lactic acid bacteria associated with the digestive tract of Atlantic salmon (Salmo salar L.)

The present study reports the effect of excessive handling stress and starvation on the lactic acid bacteria associated with the digestive tract of Atlantic salmon (Salmo salar L.). A relatively low population level (approximately 2 x 103 bacteria per gram wet tissue) of viable adherent heterotrophic bacteria was associated with the digestive tract (foregut, midgut and hindgut). Of the 752 bacterial isolates isolated from diet, water and the digestive tract, 201 isolates belonged to the carnobacteria. Of these isolates, one from the diet, one from the rearing water and 80 from the gastrointestinal tract, were further identified on the basis of 16S rDNA sequence analysis. All these isolates were identified as being Carnobacterium piscicola-like. Daily repeated stress and starvation of the fish over 11 d had no influence on the total culturable bacterial numbers or population level of C. piscicola associated with the digestive tract. C. piscicola-like isolates colonizing the various intestinal regions (foregut, midgut and hindgut) were also screened for their ability to produce growth inhibitory compounds active against the fish pathogen Aeromonas salmonicida. Of the 199 C. piscicola isolates tested, 139 inhibited growth of the pathogen.     

肠道菌群变化对肠上皮细胞Myd88蛋白及炎症因子的影响

目的 研究肠道菌群变化对体外培养的正常大鼠肠黏膜上皮细胞Myd88蛋白水平及其下游TNF-α等炎症因子的影响。方法 选取10只健康大鼠,实验室适应性喂养5 d后继续常规喂养7 d并处死,取结肠组织进行细胞培养得到原代肠黏膜上皮细胞,将所得细胞分为5组,分别用正常细胞培养液（A组）、正常大鼠肠腔菌溶液（B组）、正常大鼠黏膜菌溶液（C组）、溃疡性结肠炎大鼠肠腔菌溶液（D组）、溃疡性结肠炎大鼠黏膜菌溶液（E组）培养,通过蛋白质印迹法检测各组细胞中Myd88蛋白含量,通过酶联免疫吸附法检测TNF-α和IL-6含量。结果 D组、E组与A组比较,细胞中Myd88蛋白及TNF-α、IL-6水平显著增高（Ps＜0.01）,D、E组与B、C组比较Myd88蛋白及TNF-α、IL-6水平亦显著增高（Ps＜0.01）,而B组、C组相较于A组差异无统计学意义（Ps＞0.05）。进一步比较D组与E组、B组与C组间Myd88蛋白及TNF-α、IL-6水平差异亦无统计学意义（Ps＞0.0.5）。结论 （1）肠道菌群结构的改变可引起肠黏膜细胞Myd88通路的激活及炎症因子的释放。（2）肠道中细菌种类、数量、分布位置等因素的综合变化与肠黏膜炎症反应的发生关系密切。     

Identification of intestinal bacteria from Japanese flounder (Paralichthys olivaceus) and their ability to digest chitin

AIMS: The aim of the present study was to clarify the taxonomic status of intestinal bacteria isolated from Japanese flounder (Paralichthys olivaceus) and describe their ability to digest chitin. METHODS AND RESULTS: Phylogenetic analysis based on 16S ribosomal DNA (rDNA) sequences showed that 82 representative isolates were closely related to three major species of marine vibrios, Vibrio scophthalmi-Vibrio ichthyoenteri group (41 isolates), Vibrio fischeri (39 isolates) and Vibrio harveyi (two isolates), with similarities of 97.2-99.8%, 96.4-100% and 98.6-99.5% respectively. These findings indicate that V. scophthalmi-V. ichthyoenteri group is indigenous to the intestinal tract of Japanese flounder. Moreover, the ability of 82 isolates to digest chitin was examined using the agar plate method and PCR amplification of the chiA gene. The two V. harveyi isolates and 36 of 41 V. scophthalmi-V. ichthyoenteri isolates digested chitin and were chiA PCR positive, whereas all 39 V. fischeri isolates digested chitin but were chiA PCR negative. CONCLUSIONS: Intestinal bacteria from Japanese flounder were mainly composed of Vibrio scophthalmi-V. ichthyoenteri group and V. fischeri. Taken together, the results showed that 81 of 82 isolates could digest chitin. However, only 38 of these isolates possessed a chiA homologue which could be identified by PCR. SIGNIFICANCE AND IMPACT OF THE STUDY: The present study shows that Japanese flounder harbours bacteria of the V. scophthalmi-V. ichthyoenteri group, and these results are similar to what has been found for turbot (Scophthalmus maximus).     

Isolation and characterization of turbot (Scophtalmus maximus)-associated bacteria with inhibitory effects against Vibrio anguillarum.

More than 400 isolates from the intestine and the external surface of farmed Scophtalmus maximus as well as from fish food and hatchery water were screened for inhibitory effects against the fish pathogen Vibrio anguillarum HI 11345 and seven other fish pathogens. The bacteria with inhibitory effects were then characterized with regard to their sites of colonization, especially the intestinal regions and sites within each region. Of the total number of bacterial isolates from the intestine, 28% were inhibitory against V. anguillarum HI 11345. A marine biochemical assay was used to order the inhibitory strains into different phena. Most inhibitory bacteria were found in the rinse and mucus fractions of the gastrointestinal tract. No correlations among the different phena, site of colonization, and inhibitory effect could be found; however, a biochemical diversity was noted in the strains with an inhibitory effect. Of the isolates with an inhibitory effect against V. anguillarum HI 11345, 60% had an inhibitory effect on five other fish-pathogenic serotypes of V. anguillarum. Inhibitory effects of the isolates were also shown against Aeromonas salmonicida and Aeromonas hydrophila.     

Isolation and characterization of turbot (Scophtalmus maximus)-associated bacteria with inhibitory effects against Vibrio anguillarum.

More than 400 isolates from the intestine and the external surface of farmed Scophtalmus maximus as well as from fish food and hatchery water were screened for inhibitory effects against the fish pathogen Vibrio anguillarum HI 11345 and seven other fish pathogens. The bacteria with inhibitory effects were then characterized with regard to their sites of colonization, especially the intestinal regions and sites within each region. Of the total number of bacterial isolates from the intestine, 28% were inhibitory against V. anguillarum HI 11345. A marine biochemical assay was used to order the inhibitory strains into different phena. Most inhibitory bacteria were found in the rinse and mucus fractions of the gastrointestinal tract. No correlations among the different phena, site of colonization, and inhibitory effect could be found; however, a biochemical diversity was noted in the strains with an inhibitory effect. Of the isolates with an inhibitory effect against V. anguillarum HI 11345, 60% had an inhibitory effect on five other fish-pathogenic serotypes of V. anguillarum. Inhibitory effects of the isolates were also shown against Aeromonas salmonicida and Aeromonas hydrophila.     

Decontamination effect of electrolysed NaCl solutions on carp

AIMS: To evaluate the efficacy of electrolysed NaCl solutions (EW) for disinfecting bacterial isolates from carp, and the potential application of EW to reducing the bacterial load in whole carp and carp fillets. METHODS AND RESULTS: EW was produced by using a two-compartment batch-type electrolysed apparatus. Pure cultures (in vitro), whole carp (skin surface) and carp fillets were treated with EW to detect its antimicrobial effects. The anodic solution [EW (+)] completely inhibited growth of the isolates. Furthermore, dipping the fish samples in EW (+) reduced the mean total count of aerobic bacteria on the skin of whole carp and in fillets by 2.8 and 2.0 log(10), respectively. The cathodic solution [EW (-)] also reduced growth of the isolates from carp by ca 1.0 log(10). Moreover, the total counts of aerobic bacteria in whole carp (on the skin) and fillets were reduced by 1.28 and 0.82 log(10), respectively. CONCLUSIONS: EW (+) has a strong bactericidal effect on bacteria isolated from carp. SIGNIFICANCE AND IMPACT OF THE STUDY: Treatment with EW (+) could extend the shelf life of these fish.     

Novel ecological niche of Cetobacterium somerae, an anaerobic bacterium in the intestinal tracts of freshwater fish

AIMS: This study was conducted to clarify the taxonomic status of Bacteroides type A strains with high vitamin B(12)-producing ability that is widely distributed in the intestinal tracts of freshwater fish. METHODS AND RESULTS: Seventeen strains of Bacteroides type A isolated from five fish species were all rod-shaped and gram-negative. The strains were positive for esculin hydrolysis, nitrate reduction, resistance to bile, acid phosphatase, and negative for the production of catalase and urease and the susceptibility to vancomycin. The G+C content of DNA from the 17 strains was 29 x 1-31 x 9 mol%, and 16S rDNA sequence analysis revealed a close phylogenetic relationship between Bacteroides type A strains and Cetobacterium somerae sharing 99 x 7-100% sequence similarity. In addition, strains were capable of producing vitamin B(12) at a rate of 1 x 82-13 x 98 ng ml(-1) in 48 h. CONCLUSION: Phenotypic and phylogenetic characteristics indicated that all isolates previously classified as Bacteroides type A strains belong to C. someare. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provided the important finding of novel niche of vancomycin-resistant bacteria such as C. somerae in the intestinal tract of freshwater fish.     

中草药复方对草鱼鱼种肠道菌群与血液有形成分的影响

目的探讨中草药复方对鱼种肠道菌群和血液有形成分的影响。方法以草鱼鱼种为动物模型,分别采用平板倾注法和ATB半自动化细菌鉴定法,测定投喂中草药复方药饵前、后鱼种肠道菌群数量及其优势菌群种类。同时使用常规计数法和改良沙利法,测定鱼种血液中红细胞、白细胞和血红蛋白的含量。结果对照组鱼种肠道内的细菌总数为6．6×10^8CFU／g,其优势菌群为气单胞菌、假单胞菌和肠杆菌;投喂2．5％、5．0％和7．5％中草药复方药饵10d后,其肠道内细菌总数均有所减少,分别为3．0×10^7CFU／g、5．0×10^6CFU／g和1．5×10^7CFU／g,其优势菌群为吲哚黄杆菌、产碱假单胞菌和野油菜黄单胞菌。实验组与对照组鱼种的红细胞数量差异无显著性,但白细胞与血红蛋白的含量差异有非常显著性（P〈0．01）。结论以黄连、大黄、金银花、连翘、黄芪和甘草组成的中草药复方对鱼种肠道菌群和血液有形成分均有一定影响,表现出该复方具有较好的免疫抗病作用。     

Production of amylase by the intestinal microflora in cultured freshwater fish

The amylase-producing ability of the intestinal microflora in cultured specimens of ayu, carp, channel catfish, Japanese eel and tilapia was determined. Mean viable counts of aerobes and anaerobes ranged from 1·1×10⁶ to 3·7×10⁸ cfu g⁻¹ and from 1·3×10³ to 1·6×10⁸ cfu g⁻¹, respectively. Aeromonas spp. and Bacteroidaceae were predominant in four to five fish species. Of 206 strains examined, 65 (31·6%) produced ≥0·01 U amylase ml⁻¹. The percentage of producers differed among families and genera of bacteria and fish species. While 56% of the anaerobes produced amylase, only 20% of the aerobes did. More than 50% of Aeromonas , Bacteroidaceae and Clostridium strains produced amylase efficiently while Acinetobacter , coryneforms, Enterobacteriaceae, Moraxella , Plesiomonas and Streptococcus strains did not. High amylase production (≥0·05 U ml⁻¹) was found in 12 strains, 11 from Aeromonas and one Pseudomonas . The percentage of high amylase producers in Japanese eel was lower than the other four fish (2–30%). These results strongly suggest that the amylase produced by the intestinal microflora play an important role in the digestion of starch in freshwater fish to some extent.     

不同食料植物对东亚飞蝗肠道细菌状况的影响

目的比较在相同的环境条件下不同食料植物对东亚飞蝗肠道细菌状况的影响。方法以墨西哥玉米、野生马唐为食料植物饲喂东亚飞蝗,在其成虫肠道内和粪沙中分离纯化细菌,获得22株菌株,分别对其培养性状、菌体形态、染色反应和生理生化性状进行系统研究。结果上述22个菌株分别属于稀有杆菌属（Rarobact-er）、短状杆菌属（Brachybacterium）、棒杆菌属（Corynebacterium）、棍状菌属（Clavibacter）、葡萄球菌属（Staphylococ-cus）、丙酸杆菌属（Propionibacterium）、埃希菌属（Eschrichia）、气微杆菌属（Aercmicrobium）、沙雷菌属（Serratia）、克雷伯菌属（Klebsiella）、沙门菌属（Salmonella）、志贺菌属（Shigella）、口腔球菌属（Stomatococcus）、短杆菌属（Brevibacteri-um）、地杆菌属（Terrbacter）、微小杆菌属（Exiguobacterium）、皮杆菌属（Dermabacter）、短小杆菌属（Curtobacterium）、纤维单胞菌属（Cellulomonas）、微杆菌属（Microbacterium）、乳杆菌属（Lactobacillus）和凝结芽胞杆菌属（Bacilluscoag-ulans）。结论不同食料植物对东亚飞蝗肠道细菌种类和数量有很大的影响。     

Effect of pH on the activity of proteinases in intestinal mucosa,chyme, and microbiota of fish from the Cuciurgan reservoir

Proteolytic activities of the intestinal mucosa, chyme, and enteral microbiota have been studied in a wide range of pH values in five fish species from the Cuciurgan reservoir (Moldova). Differences in pH dependence of the intestinal proteinase activity of fish are determined by their feeding type. The maximum activity of proteinases is found in the pumpkinseed Lepomis gibbosus. The minimum activity of proteinases has been demonstrated by the zander Zander lucioperca. The pH optimum of the mucosa and chyme in all fish species (except for the European perch Perca fluviatilis) is 10. The pH optimum of the intestinal microflora varies from 6.0 (in the common carp Cyprinus carpio) to 10 (in the crucian carp Carassius carassius), whereas that in the perch from the Cuciurgan and Rybinsk reservoirs is 7. The majority of fish species, mostly Zander lucioperca and Lepomis gibbosus, are characterized by high proteniase activity of the microbiota, in the pH ranging from 6 to 9. It is assumed that proteinases in the enteral microbiota of fish are able to make up for the relatively low activity of those synthesized by their digestive system in the range of low pH values.     

Effect of temperature on proteinase activities of enteral microbiota and intestinal mucosa of fish of different ecological group

Effect of temperature on proteinases activities of enteral microbiota and of intestinal mucosa was studied in five fish species (roach Rutilus rutilus, crucian carp Carassius carassius, common perch Perca fluviatilis, pike-perch Zander lucioperca, and pike Esox lucius) belonging by the nutrition type to different ecological groups. Essential differences of temperature characteristics of proteinases of intestinal mucosa and of enteral microbiota are revealed in fish belonging by the nutrition type to different ecologic groups. The character of the t0-function of proteinases of intestinal mucosa and enteral microbiota by casein and hemoglobin as a rule is different. The highest values of relative proteinases activities for casein in the zone of low temperatures (38 and 45.3 % of the maximal activity) are found at study of proteinases of enteral microbiota in common perch and crucian carp. The latter indicates a significant adaptability of the enteral microbiota proteinases of common perch and crucial carp to functioning at low temperatures.     

Diversity of microbial communities of the intestinal mucosa and intestinal contents of fish from Lake Chany (Western Siberia)

The diversity of microbial communities associated with the intestinal mucosa and the intestinal contents of fish with different nutritional profiles have been investigated. Differences in the intestinal microbiota of fish with different dietary preferences have been revealed using group-specific primers for the main large taxa of bacteria. Representatives of the phyla Planctomycetes, Vernicomicrobia, and Cyanobacteria have been detected in the intestinal contents of all investigated nonpredatory (crucian carp, roach, and dace) and predatory (pikeperch, pike, and perch) fish. Representatives of the phylum Firmicutes were detected in the intestinal mucosa and intestinal contents of predatory fish species, but not in those of the nonpredatory fish.     

蜜蜂成虫工蜂肠道可培养细菌群落结构分析

【目的】研究2种蜜蜂(健康意大利蜜蜂和健康中华蜜蜂)成虫工蜂肠道可培养细菌的群落结构组成。【方法】利用16S r RNA基因的聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)分析技术,结合菌落形态观察和生理生化特征鉴定细菌种类。【结果】从2种蜜蜂成虫工蜂肠道200株可培养细菌得到18种不同细菌遗传型,分属于肠杆菌科(Enterobacteriaceae)、弧菌科(Vibrionaceae)和肠球菌科(Enterococcaceae)3个科。其中肠杆菌科是肠道可培养细菌最优势的细菌种类。同样以序列相似性大于97%的菌株归为相同细菌种类为标准,找到了2种蜜蜂可培养细菌的共有菌种,结合菌落形态观察和生理生化特征鉴定,确定肠道可培养细菌为肠杆菌属8株,克雷伯氏菌属1株,肠球菌属2株,以及气单胞菌属1株。【结论】通过研究健康意大利蜜蜂和中华蜜蜂成虫工蜂肠道可培养细菌群落结构组成,可为开展蜜蜂的微生态研究提供基础性资料。