海洋动植物共附生微生物的分离和抗菌活性研究

从海参、海胆、海葵、海兔、石莼、羊栖菜、裙带菜分离得到125种共附生海洋微生物,以6种敏感菌为指示菌,从中获得具有抑菌活性的细菌21株,放线菌8株,真菌2株。21株抑菌海洋细菌中芽孢杆菌属为7株,占33．3％,弧菌属为11种,占52．2％,其余3株为假单孢杆菌属,占14．5％。8株抑菌海洋放线菌中链霉菌属为5株,占62．5％,小单孢菌属为3株,占36．5％。2株抑菌海洋真菌均为青霉属。     

Bacterial production of histamine in some tropical fish

Quantitative and qualitative distribution of histamine-forming bacteria associated with the fish Rastrelliger kanagurta, Sardinella longiceps, Sillago sihama and Liza subviridis, were investigated. These bacteria constituted a significant portion of the total bacterial population of fish and the values obtained in the present study were higher than those previously reported. The order of quantitative abundance of histamine-forming bacteria in the fish examined was: S. longiceps greater than R. kanagurta greater than S. sihama greater than L. subviridis. The bacterial genera isolated were Vibrio sp., Bacillus sp., Pseudomonas sp., Aeromonas sp. and Micrococcus sp., and among them Vibrio was dominant. Growth of the isolates (Vibrio sp., V. fischeri and Bacillus sp.) at different temperatures, pH and sodium chloride concentrations indicated them to be mesophilic, euryhaline and tolerant to acidic and alkaline pH. Bacillus sp. produced more histamine in R. kanagurta, while V. fisheri produced more histamine in S. longiceps.     

Taxonomic composition of bacteria associated with cultivated mollusks Crassostrea lugubris and Perna viridis and with the water of the Gulf of Nha Trang Lagoon, Vietnam

One hundred and four strains of heterotrophic bacteria have been isolated and characterized from two species of bivalve mollusks cultivated in the Gulf of Nha Trang (Vietnam) and from the water of a mariculture farm. The isolates have been identified on the basis of morphological, physiological, biochemical, and chemotaxonomic properties, as well as by the content of G+C bases in DNA. In the microflora of mollusks, Vibrio alginolyticus was predominant; the pathogenic species V. harveyi and V. splendidus were found as well. Staphylococci and bacilli occupied the second place in abundance after vibrios. In addition, coryneforms and enterobacteria, as well as Pseudomonas spp. and Pseudoalteromonas spp., were revealed. The composition of the water microflora was more diverse as compared with the microflora of mollusks. In the water, Bacillus spp., Vibrio spp., and Pseudomonas spp. were predominant. Brevibacterium spp. and other coryneform bacteria, as well as enterobacteria, occurred in significant amounts. In addition, Pseudoalteromonas spp., Marinococcus sp., Halobacillus sp., Shewanella sp., Sulfitobacter sp., and bacteria of the CFB cluster were noticed. The presence of pathogenic and conditionally pathogenic bacterial species in the water and mollusks is probably the reason for the high death rate of cultivated animals at the mariculture farm.     

Isolation and phylogenetic analysis of bacteria with antimicrobial activities from the Mediterranean sponges Aplysina aerophoba and Aplysina cavernicola

The aim of this study was to isolate bacteria with antimicrobial activities from the marine sponges Aplysina aerophoba and Aplysina cavernicola. The obtained 27 isolates could be subdivided into eight phylogenetically different clusters based on comparative sequence analysis of their 16S rDNA genes. The sponge isolates were affiliated with the low (Bacillus) and high G+C Gram-positive bacteria (Arthobacter, Micrococcus), as well as the alpha-Proteobacteria (unknown isolate) and gamma-Proteobacteria (Vibrio, Pseudoalteromonas). One novel Bacillus species was identified and two species were closely related to previously uncharacterized strains. Isolates with antimicrobial activity were numerically most abundant in the genera Pseudoalteromonas and the alpha-Proteobacteria. The sponge isolates show antimicrobial activities against Gram-positive and Gram-negative reference strains but not against the fungus Candida albicans. A general pattern was observed in that Gram-positive bacteria inhibited Gram-positive strains while Gram-negative bacteria inhibited Gram-negative isolates. Antimicrobial activities were also found against clinical isolates, i.e. multi-resistant Staphylococcus aureus and Staphylococcus epidermidis strains isolated from hospital patients. The high recovery of strains with antimicrobial activity suggests that marine sponges represent an ecological niche which harbors a hitherto largely uncharacterized microbial diversity and, concomitantly, a yet untapped metabolic potential.     

Bacterial communities of brown and red algae from Peter the Great Bay, the Sea of Japan

The structure of microbial communities of brown algae, red algae, and of the red alga Gracilaria verrucosa, healthy and affected with rotten thallus, were comparatively investigated; 61 strains of heterotrophic bacteria were isolated and characterized. Most of them were identified to the genus level, some Vibrio spp., to the species level according to their phenotypic properties and the fatty acid composition of cellular lipids. The composition of the microflora of two species of brown algae was different. In Chordaria flagelliformis, Pseudomonas spp. prevailed, and in Desmarestia viridis, Bacillus spp. The composition of the microflora of two red algae, G. verrucosa and Camphylaephora hyphaeoides, differed mainly in the ratio of prevailing groups of bacteria. The most abundant were bacteria of the CFB cluster and pseudoalteromonads. In addition, the following bacteria were found on the surface of the algae: Sulfitobacter spp., Halomonas spp., Acinetobacter sp., Planococcus sp., Arthrobacter sp., and Agromyces sp. From tissues of the affected G. verrucosa, only vibrios were isolated, both agarolytic and nonagarolytic. The existence of specific bacterial communities characteristic of different species of algae is suggested and the relation of Vibrio sp. to the pathological process in the tissues of G. verrucosa is supposed.     

Assessing the diversity of bacterial communities from marine sponges and their bioactive compounds

Symbiotic bacteria play vital roles in the survival and health of marine sponges. Sponges harbor rich, diverse and species-specific microbial communities. Symbiotic marine bacteria have increasingly been reported as promising source of bioactive compounds. A culturomics-based study was undertaken to study the diversity of bacteria from marine sponges and their antimicrobial potential. We have collected three sponge samples i.e. Acanthaster carteri, Rhytisma fulvum (soft coral) and Haliclona caerulea from north region (Obhur) of Red Sea, Jeddah Saudi Arabia. Total of 144 bacterial strains were isolated from three marine sponges using culture dependent method. Screening of isolated strains showed only 37 (26%) isolates as antagonists against oomycetes pathogens (P. ultimum and P. capsici). Among 37 antagonistic bacteria, only 19 bacterial strains exhibited antibacterial activity against human pathogens (Methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 8739, Enterococcus faecalis ATCC 29212). Four major classes of bacteria i.e γ-Proteobacteria, α-Proteobacteria, Firmicutes and Actinobacteria were recorded from three marine sponges where γ-Proteobacteria was dominant class. One potential bacterial strain Halomonas sp. EA423 was selected for identification of bioactive metabolites using GC and LC-MS analyses. Bioactive compounds Sulfamerazine, Metronidazole-OH and Ibuprofen are detected from culture extract of strain Halomonas sp. EA423. Overall, this study gives insight into composition and diversity of antagonistic bacterial community of marine sponges and coral from Red Sea and presence of active metabolites from potential strain. Our results showed that these diverse and potential bacterial communities further need to be studied to exploit their biotechnological significance.     

Diversity and antibacterial activity of bacteria isolated from the coastal marine sponges Amphilectus fucorum and Eurypon major

Aims: To assess the diversity and antimicrobial activity of culturable bacteria associated with two temperate‐water marine sponges, Amphilectus fucorum and Eurypon major. Methods and Results: Sponge samples were collected in August 2008 and bacteria were cultured on several different media. The 16S rRNA gene of representative strains was sequenced to allow classification. It was found that Proteobacteria were the dominant group of bacteria cultured from both sponges, but overall, the bacterial composition was diverse and distinct between the sponges. The most notable features were the significantly higher proportion of firmicutes in E. major and the low frequency of actinobacteria in both sponges. Four bacterial isolates were identified as potentially novel species and will be characterised in future studies. Approximately 400 cultured bacteria were screened for antimicrobial activity against a collection of indicator strains, with only eight strains, all Pseudovibrio spp., displaying any such activity. These strains were active against Escherichia coli and Bacillus subtilis but not Staphylococcus aureus or a selection of fungal strains. Conclusions: Diverse and distinct populations of culturable bacteria are present in the coastal sponges A. fucorum and E. major. Only a minority of isolates produce antibacterial metabolites in culture, but this activity is common in Pseudovibrio spp. Significance and Impact of the Study: This study illustrates the diversity of sponge‐associated bacteria and the need to increase our knowledge about the function of these symbiotic bacteria. The data suggest that production of antibacterial metabolites is restricted to a subset of species, with the majority involved in other functions. The importance of Pseudovibrio as a reservoir of antibacterial metabolites is also highlighted.     

Antifouling activities against colonizer marine bacteria of extracts from marine invertebrates collected in the Colombian Caribbean Sea and on the Brazilian coast (Santa Catarina)

The growth inhibition of 12 native marine bacteria isolated from Aplysina sponge surfaces, the shell of a bivalve, and Phytagel immersed for 48 h in sea water were used as indicator of the antifouling activity of the extracts of 39 marine organisms (octocorals, sponges, algae, and zoanthid) collected in the Colombian Caribbean Sea and on the Brazilian coast (Santa Catarina). Gram-negative bacteria represented 75% of the isolates; identified strains belonged to Oceanobacillus iheyensis, Ochrobactrum pseudogrignonense, Vibrio campbellii, Vibrio harveyi, and Bacillus megaterium species and seven strains were classified at genus level by the 16S rRNA sequencing method. The extracts of the octocorals Pseudopterogorgia elisabethae, four Eunicea octocorals, and the sponges Topsentia ophiraphidites, Agelas citrina, Neopetrosia carbonaria, Monanchora arbuscula, Cliona tenuis, Iotrochota imminuta, and Ptilocaulis walpersii were the most active, thus suggesting those species as antifoulant producers. This is the first study of natural antifoulants from marine organisms collected on the Colombian and Brazilian coasts.     

柑橘黄龙病寄主长春花内生细菌的分离及功能鉴定

【目的】感柑橘黄龙病长春花植株与健康长春花植株不同部位内生细菌菌群结构及功能对柑橘黄龙病菌与长春花内生细菌的相关性研究提供理论基础。【方法】利用兼性厌氧可培养技术以及植物内生菌功能特性分析相结合的方法。【结果】分别从感病和健康长春花叶、茎、根的组织中分离获得67株内生细菌,与GenBank中29种细菌的相似性达到97%-100%。其中短小杆菌属(Curtobacterium sp.)、欧文氏菌属(Erwinia sp.)、蜡样芽胞杆菌(Bacillus cereus)为感病长春花内生细菌的优势菌群,鞘胺醇单胞菌属(Brevundimonas sp.)、芽胞杆菌属(Bacillus sp.)为健康长春花内生细菌的优势菌群;马胃葡萄球菌(Staphylococcus equorum)为两者的共同优势菌群。29种内生细菌进行功能分析,其中6株内生细菌至少具有4种功能特性,分属于马胃葡萄球菌、苏云金芽孢杆菌、巨大芽孢杆菌、短小杆菌属、摩氏摩根菌(Morganella morganii)及溶杆菌属(Lysobacter sp.)5个属。【结论】感病与健康长春花植株中均含有丰富的内生细菌且差异较大,黄龙病菌的存在改变了长春花原有内生细菌的菌群结构。通过分析菌群的差异,有望找到与柑橘黄龙病菌生长相关的菌种。     

Surface microflora of four smear-ripened cheeses

The microbial composition of smear-ripened cheeses is not very clear. A total of 194 bacterial isolates and 187 yeast isolates from the surfaces of four Irish farmhouse smear-ripened cheeses were identified at the midpoint of ripening using pulsed-field gel electrophoresis (PFGE), repetitive sequence-based PCR, and 16S rRNA gene sequencing for identifying and typing the bacteria and Fourier transform infrared spectroscopy and mitochondrial DNA restriction fragment length polymorphism (mtDNA RFLP) analysis for identifying and typing the yeast. The yeast microflora was very uniform, and Debaryomyces hansenii was the dominant species in the four cheeses. Yarrowia lipolytica was also isolated in low numbers from one cheese. The bacteria were highly diverse, and 14 different species, Corynebacterium casei, Corynebacterium variabile, Arthrobacter arilaitensis, Arthrobacter sp., Microbacterium gubbeenense, Agrococcus sp. nov., Brevibacterium linens, Staphylococcus epidermidis, Staphylococcus equorum, Staphylococcus saprophyticus, Micrococcus luteus, Halomonas venusta, Vibrio sp., and Bacillus sp., were identified on the four cheeses. Each cheese had a more or less unique microflora with four to nine species on its surface. However, two bacteria, C. casei and A. arilaitensis, were found on each cheese. Diversity at the strain level was also observed, based on the different PFGE patterns and mtDNA RFLP profiles of the dominant bacterial and yeast species. None of the ripening cultures deliberately inoculated onto the surface were reisolated from the cheeses. This study confirms the importance of the adventitious, resident microflora in the ripening of smear cheeses.     

Differences Between Bacterial Communities Associated with the Surface or Tissue of Mediterranean Sponge Species

Bacterial communities associated with the surfaces of several Mediterranean sponge species (Agelas oroides, Chondrosia reniformis, Petrosia ficiformis, Geodia sp., Tethya sp., Axinella polypoides, Dysidea avara, and Oscarella lobularis) were compared to those associated with the mesohyl of sponges and other animate or inanimate reference surfaces as well as with those from bulk seawater. Denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified bacterial 16S ribosomal RNA genes obtained from the surfaces and tissues of these sponges demonstrated that the bacterial communities were generally different from each other. The bacterial communities from sponges were different from those on reference surfaces or from bulk seawater. Additionally, clear distinctions in 16S rDNA fingerprint patterns between the bacterial communities from mesohyl samples of "high-microbial abundance (HMA) sponges" and "low-microbial abundance sponges" were revealed by DGGE and cluster analysis. A dominant occurrence of particularly GC-rich 16S ribosomal DNA (rDNA) fragments was found only in the DGGE banding pattern obtained from the mesohyl of HMA sponges. Furthermore, sequencing analysis of 16S rDNA fragments obtained from mesohyl samples of HMA sponges revealed a dominant occurrence of sponge-associated bacteria. The bacterial communities within the mesohyl of HMA sponges showed a close relationship to each other and seem to be sponge-specific.     

Identification of foodborne bacteria by infrared spectroscopy using cellular fatty acid methyl esters

Identification of bacterial species by profiling fatty acid methyl esters (FAMEs) has commonly been carried out by using a 20-min capillary gas chromatographic procedure followed by library matching of FAME profiles using commercial MIDI databases and proprietary pattern recognition software. Fast GC (5 min) FAME procedures and mass spectrometric methodologies that require no lipid separation have also been reported. In this study, bacterial identification based on the rapid (2 min) infrared measurement of FAME mixtures was demonstrated. The microorganisms investigated included Gram positive bacteria Staphylococcus aureus, Listeria monocytogenes, Bacillus anthracis, and Bacillus cereus, and Gram negative bacteria from the family Enterobacteriacae: Yersinia enterocolitica, Salmonella typhimurium, Shigella sonnei, and Escherichia coli (four strains of E. coli), and non-Enterobacteriacae: Vibrio cholerae, Vibrio vulnificus, and Vibrio parahemolyticus. Foodborne bacterial mixtures of FAMEs were measured by using an attenuated total reflection (ATR)-Fourier transform infrared (FTIR) spectroscopic procedure and discriminated by multivariate analysis. Results showed that the Enterobacteriacae could be discriminated from the vibrios. The identification was at the level of species (for the Bacillus and Vibrio genera) or strains (for the E. coli species). A series of bacterial FAME test samples were prepared and analyzed for accuracy of identification, and all were correctly identified. Our results suggest that this infrared strategy could be used to identify foodborne pathogens.     

Antimicrobial activity of bacteria from marine sponge Suberea mollis and bioactive metabolites of Vibrio sp. EA348

Discovery of potential bioactive metabolites from sponge-associated bacteria have gained attraction in recent years. The current study explores the potential of sponge (Suberea mollis) associated bacteria against bacterial and fungal pathogens. Sponge samples were collected from Red sea in Obhur region, Jeddah, Saudi Arabia. Of 29 isolated bacteria belong to four different classes i.e. Firmicutes (62%), γ-Proteobacteria (21%), α-Proteobacteria (10%) and Actinobacteria (7%). Among them nineteen (65%) bacterial strains showed antagonistic activity against oomycetes and only 3 (10%) bacterial strains were active against human pathogenic bacteria tested. Most bioactive genera include Bacillus (55%), Pseudovibrio (13%) and Ruegeria (10%). Enzyme production (protease, lipase, amylase, cellualse) was identified in 12 (41%) bacterial strains where potential strains belonging to γ-Proteobacteria and Firmicutes groups. Production of antimicrobial metabolites and hydrolysates in these bacteria suggest their potential role in sponge against pathogens. Further bioactive metabolites from selected strain of Vibrio sp. EA348 were identified using LC-MS and GC–MS analyses. We identified many active metabolites including antibiotics such as Amifloxacin and fosfomycin. Plant growth hormones including Indoleacetic acid and Gibberellin A3 and volatile organic compound such as methyl jasmonate were also detected in this strain. Our results highlighted the importance of marine bacteria inhabiting sponges as potential source of antimicrobial compounds and plant growth hormones of pharmaceutical and agricultural significance.     

Effect of Bacteria Associated with the Green Alga Ulva reticulata on Marine Micro- and Macrofouling

The green alga Ulva reticulata (Forsskal) is often free from biofouling in Hong Kong waters. An early study indicated that bioactive substances from this alga inhibit settlement of the polychaete Hydroides elegans (Haswell). It is also predicted that epibiotic bacteria protect this alga from micro- and macrofouling. In this study, bacterial strains from the surface of U. reticulata were isolated and their inhibitive activities on micro- and macrofouling assayed. The strains were identified by 16S rRNA analysis as belonging to the genera Alteromonas , Pseudoalteromonas and Vibrio . There was no significant effect of these strains or their extracts (aqueous and ethanol) on the growth of five Vibrio strains isolated from natural biofilm. Two bacterial strains ( Alteromonas sp. and Vibrio sp. 3) were non-toxic to the benthic diatom Nitzschia paleacea (Grunow) while the other five strains caused a low level of mortality. No one bacterial strain was toxic to the larvae of H. elegans . Aqueous extract of one of the isolated bacterial species, i.e. Vibrio sp. 2, significantly ( p <0.00001) inhibited the settlement and metamorphosis of H. elegans larvae. The putative antifouling compounds have a molecular weight of >100 kD. On the other hand, biofilm of Pseudoalteromonas sp. 2 and aqueous extract of Vibrio sp. 2 suppressed the settlement of larvae induced by 3-isobutyl-1-methylxanthine (IBMX). Other epibiotic bacteria and their extracts had neither inhibitive nor inductive effects on larval settlement of H. elegans . The results indicate that the antifouling mechanism of U. reticulata may be dependent not only on materials from the macroalga itself but also on the epibiotic bacteria on the algal surface.     

Bioactive potential of Streptomyces associated with marine sponges

The present work deals with isolation of Streptomyces associated with marine sponges and its bioactive potential. Streptomyces sp. were isolated from the marine sponges Callyspongia diffusa, Mycale mytilorum, Tedania anhelans and Dysidea fragilis. From the initial screening, 94 cultures of Streptomyces were obtained and from these 58 cultures exhibited antagonism against bacteria, 36 strains against fungi and 27 strains exhibited broad spectrum activity against both. The submerged culture extracts of the 58 anti-bacterial isolates were analysed and of these 58 strains, 37 strains showed positive inhibition against Bacillus subtilis, 43 against Staphylococcus aureus, 10 against Vibrio cholerae and 10 against Escherichia coli. The antifungal activities of the 36 strains were also evaluated and 27 strains showed positive inhibition against Aspergillus niger, 23 against Saccharomyces cerevisiae and 16 against Candida albicans. The production of polyene substances from the active extracts was confirmed by UV spectral analysis by the absorbance peaks that ranged from 225 to 262 nm and the TLC (R _f values) ranging from 0.40 to 0.78. The results indicate that Streptomyces strains isolated from marine sponges produce potential antibacterial, antifungal and broad spectrum antibiotic compounds.     

Occurrence of tetracycline resistance genes tet(M) and tet(S) in bacteria from marine aquaculture sites

Occurrence of tetracycline resistance genes encoding ribosomal protection proteins was examined in 151 tetracycline-resistant bacterial isolates from fish and seawater at coastal aquaculture sites in Japan and Korea. The tet(M) gene was detected in 34 Japanese and Korean isolates, which included Vibrio sp., Lactococcus garvieae, Photobacterium damsela subsp. piscicida, and unidentified Gram-positive bacteria. The majority of these bacterial isolates displayed high-level resistance with a minimum inhibitory concentrations (MICs) equal to or greater than 250 microg/ml of oxytetracycline and only four isolates had MICs less than 31.3 microg/ml. 16S rDNA RFLP typing of tet(M)-positive Vibrio isolates suggests that these are clonal populations of the same phylotype specific to a particular location. One Vibrio clone (phylotype III), however, is widely disseminated, being detected during different sampling years, at different locations, and in different fish species in both Japan and Korea. The tet(S) gene was detected in L. garvieae from yellowtail in Japan and in Vibrio sp. from seawater in Korea. This is the first report of tet(S) occurrence in Gram-negative facultative anaerobes. These results suggest that tet(M) and tet(S) genes are present in fish intestinal and seawater bacteria at aquaculture sites and could be an important reservoir of tetracycline resistance genes in the marine environment.     

Phylogenetic diversity, host-specificity and community profiling of sponge-associated bacteria in the northern Gulf of Mexico

Background

Marine sponges can associate with abundant and diverse consortia of microbial symbionts. However, associated bacteria remain unexamined for the majority of host sponges and few studies use phylogenetic metrics to quantify symbiont community diversity. DNA fingerprinting techniques, such as terminal restriction fragment length polymorphisms (T-RFLP), might provide rapid profiling of these communities, but have not been explicitly compared to traditional methods.

Methodology/Principal Findings

We investigated the bacterial communities associated with the marine sponges Hymeniacidon heliophila and Haliclona tubifera, a sympatric tunicate, Didemnum sp., and ambient seawater from the northern Gulf of Mexico by combining replicated clone libraries with T-RFLP analyses of 16S rRNA gene sequences. Clone libraries revealed that bacterial communities associated with the two sponges exhibited lower species richness and lower species diversity than seawater and tunicate assemblages, with differences in species composition among all four source groups. T-RFLP profiles clustered microbial communities by source; individual T-RFs were matched to the majority (80.6%) of clone library sequences, indicating that T-RFLP analysis can be used to rapidly profile these communities. Phylogenetic metrics of community diversity indicated that the two sponge-associated bacterial communities include dominant and host-specific bacterial lineages that are distinct from bacteria recovered from seawater, tunicates, and unrelated sponge hosts. In addition, a large proportion of the symbionts associated with H. heliophila were shared with distant, conspecific host populations in the southwestern Atlantic (Brazil).

Conclusions/Significance

The low diversity and species-specific nature of bacterial communities associated with H. heliophila and H. tubifera represent a distinctly different pattern from other, reportedly universal, sponge-associated bacterial communities. Our replicated sampling strategy, which included samples that reflect the ambient environment, allowed us to differentiate resident symbionts from potentially transient or prey bacteria. Pairing replicated clone library construction with rapid community profiling via T-RFLP analyses will greatly facilitate future studies of sponge-microbe symbioses.     

In vitro suppression of fungi caused by combinations of apparently non-antagonistic soil bacteria

We hypothesized that apparently non-antagonistic soil bacteria may contribute to suppression of fungi during competitive interactions with other bacteria. Four soil bacteria (Brevundimonas sp., Luteibacter sp., Pedobacter sp. and Pseudomonas sp.) that exhibited little or no visible antifungal activity on different agar media were prescribed. Single and mixed strains of these species were tested for antagonism on a nutrient-poor agar medium against the plant pathogenic fungi Fusarium culmorum and Rhizoctonia solani and the saprotrophic fungus Trichoderma harzianum. Single bacterial strains caused little to moderate growth reduction of fungi (quantified as ergosterol), most probably due to nutrient withdrawal from the media. Growth reduction of fungi by the bacterial mixture was much stronger than that by the single strains. This appeared to be mostly due to competitive interactions between the Pseudomonas and Pedobacter strains. We argue that cohabitation of these strains triggered antibiotic production via interspecific interactions and that the growth reduction of fungi was a side-effect caused by the sensitivity of the fungi to bacterial secondary metabolites. Induction of gliding behavior in the Pedobacter strain by other strains was also observed. Our results indicate that apparently non-antagonistic soil bacteria may be important contributors to soil suppressiveness and fungistasis when in a community context.     

凉水保护区土壤产类漆酶-多铜氧化酶细菌群落结构

在凉水国家级自然保护区3种主要林型红松(Pinus koraiensis)、白桦(Betula platyphylla)及云杉(Picea dietrich)林采集林下土壤样品,以铜离子作为筛选剂处理后,结合平板分离法与基于16S rDNA V3区片段的变性梯度凝胶电泳(DenaturingGradient Gel Electrophoresis,DGGE)技术,调查了土壤样品中产类漆酶-多铜氧化酶(laccase-like multicopper oxidase,LMCO)细菌的群落结构。这是研究产类漆酶-多铜氧化酶细菌在环境中存在的种、属及分布的新尝试。平板分离获得10株细菌均为芽孢杆菌属(Bacillus sp.),其中梭状芽孢杆菌(Bacillus fusiformis)未见相关报道。通过DGGE图谱分析可知,产类漆酶-多铜氧化酶细菌在研究地不同林型土壤中的群落结构无明显差异,在红松林土壤中多样性最为丰富。DGGE条带测序结果表明,取样地土壤中产类漆酶细菌主要为罗尔斯顿菌属(Ralstonia sp.)、肠杆菌属(Enterobacter sp.)、芽孢杆菌属和一些未培养细菌。     

氟化物对家蚕耐氟和氟敏感品种肠道中留存产酶菌群落组成和多样性的影响

【目的】研究氟化物对家蚕Bombyx mori肠道内留存产酶菌的影响, 有助于了解家蚕耐氟和氟敏品种的耐氟力差异。【方法】分别给家蚕耐氟品种T6和氟敏品种734添食NaF溶液浸泡后的新鲜桑叶, 至5龄第3天取材。采用筛选培养基筛选产蛋白酶、 纤维素酶、 脂肪酶、 淀粉酶的菌株, 并结合16S rDNA系统发育关系, 对菌株进行分类鉴定。【结果】家蚕肠道内产消化酶细菌有芽孢杆菌属Bacillus、 葡萄球菌属Staphylococcus、 肠杆菌属Enterobacter和不动杆菌属Acinetobacter和微小杆菌属Exiguobaterium, 其中芽孢杆菌Bacillus sp.、 葡萄球菌Staphylococcus sp. 和不动杆菌Acinetobacter sp.细菌可同时产4种酶。氟中毒后T6肠道内产酶菌由5种减少到4种, 734肠道内产酶菌由2种减少到1种。【结论】家蚕肠道内留存的产酶菌与家蚕自身的耐氟能力相关。