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1.
Cecilia Wentrup Annelie Wendeberg Julie Y Huang Christian Borowski Nicole Dubilier 《The ISME journal》2013,7(6):1244-1247
The deep-sea mussel Bathymodiolus harbors chemosynthetic bacteria in its gills that provide it with nutrition. Symbiont colonization is assumed to occur in early life stages by uptake from the environment, but little is known about this process. In this study, we used fluorescence in situ hybridization to examine symbiont distribution and the specificity of the infection process in juvenile B. azoricus and B. puteoserpentis (4–21 mm). In the smallest juveniles, we observed symbionts, but no other bacteria, in a wide range of epithelial tissues. This suggests that despite the widespread distribution of symbionts in many different juvenile organs, the infection process is highly specific and limited to the symbiotic bacteria. Juveniles⩾9 mm only had symbionts in their gills, indicating an ontogenetic shift in symbiont colonization from indiscriminate infection of almost all epithelia in early life stages to spatially restricted colonization of gills in later developmental stages. 相似文献
2.
Alexandra Demiri Alexandra Meziti Sokratis Papaspyrou Maria Thessalou-Legaki Konstantinos Ar. Kormas 《Central European Journal of Biology》2009,4(4):558-566
We investigated the diversity of the bacterial 16S rRNA genes occurring on the abdominal setal tufts and in the emptied midgut
of the marine mudshrimp Pestarella tyrrhena (Decapoda: Thalassinidea). There were no dominant phylotypes on the setal tufts. The majority of the phylotypes belonged
to the phylum Bacteroidetes, frequently occurring in the water column. The rest of the phylotypes were related to anoxygenic
photosynthetic α-Proteobacteria and to Actinobacteria. This bacterial profile seems more of a marine assemblage rather than
a specific one suggesting that no specific microbial process can be inferred on the setal tufts. In the emptied midgut, 64
clones were attributed to 16 unique phylotypes with the majority (40.6%) belonging to the γ-Proteobacteria, specifically to
the genus Vibrio, a marine group with known symbionts of decapods. The next most abundant group was the ɛ-Proteobacteria (28.1%), with members
as likely symbionts related to the processes involving redox reactions occurring in the midgut. In addition, phylotypes related
to the Spirochaetes (10.9%) were also present, with relatives capable of symbiosis conducting a nitrite associated metabolism.
Entomoplasmatales, Bacteroidetes and Actinobacteria related phylotypes were also found. These results indicate a specific
bacterial community dominated by putative symbiotic Bacteria within the P. tyrrhena’s midgut. 相似文献
3.
In this study, the cellular organization of the gill that harbors symbiotic bacteria is described in the thyasirid Thyasira falklandica collected from South Shetlands in Antarctic. Sections of the gills revealed that T. falklandica belongs to the gill type 3, as described by Dufour (Biol Bull, 208:200–212, 2005), with an elongated lateral zone along the
frontal-abfrontal axis of the gill filaments. The ciliated and intermediary zones looked similar to those described in symbionts-bearing
bivalves. The lateral zone is more complex in T. falklandica than in other Thyasiridae already described. Such a zone is composed of four different cell types. Bacteriocytes are abundant
in the frontal and abfrontal positions, while the middle part of the lateral zone is occupied mostly by numerous granule cells
devoid of bacteria. All along the lateral zone, TEM and SEM observations show some ciliated cells, which are regularly interspersed
between bacteriocytes and/or granule cells. Such cells, according to the long double ciliary roots of their cilia, should
have a sensory function. Intercalary cells, which have never been observed between bacteriocytes, are restricted to the middle
part of the lateral zone where their expansions overlap the adjacent granule cells. Bacterial symbionts occur only extracellularly
among long microvilli differentiated by the bacteriocytes. They are abundant, usually spherical in shape (around 0.7 μm length),
and covered by the glycocalix from bacteriocyte microvilli. According to TEM views, the empty vesicles located in the periplasmic
space should be sulfur storage, as known for other sulfur-oxidizing symbionts. 相似文献
4.
A. Meziti K. Ar. Kormas M. -A. Pancucci-Papadopoulou M. Thessalou-Legaki 《Russian Journal of Marine Biology》2007,33(2):84-91
We used sequencing and phylogenetic analysis of PCR-amplified 16S rRNA genes from bacteria that are associated with the esophagus/pharynx,
stomach and intestine of two marine sympatric invertebrates but with different feeding mechanisms, namely the sea urchin Paracentrotus
lividus (grazer) and the ascidian Microcomus sp. (suspension feeder). Amplifiable DNA was retrieved from all sections except the pharynx of the ascidian. Based on the
inferred phylogeny of the retrieved sequences, the sea urchin’s esophagus is mainly characterized mostly by bacteria belonging
to α-, γ-Proteobacteria and Bacteriodetes, most probably originating from the surrounding environment. The stomach revealed
phylotypes that belonged to γ- and δ-Proteobacteria, Verrucomicrobia and Fusobacteria. Since the majority of their closest
relatives are anaerobic species and they could be putative symbionts of the P. lividus stomach, in which anaerobic conditions also prevail. Seven out of eight phylotypes found in the sea urchin’s intestine belonged
to sulfate reducing δ-Proteobacteria, and one to γ-Proteobacteria, with possible nutritional activities, i.e. degradation
of complex organic compounds which is beneficial for the animal. The bacterial phylotypes of the ascidian digestive tract
belonged only to the phyla of Actinobacteria and Proteobacteria. The stomach phylotypes of the ascidian were related to pathogenic
bacteria possibly originating from the water column, while the intestine seemed to harbour putative symbiotic bacteria that
are involved in the degradation of nitrogenous and other organic compounds, thus assisting ascidian nutrition.
The text was submitted by the authors in English. 相似文献
5.
Marine invertebrates hosting chemosynthetic bacterial symbionts are known from multiple phyla and represent remarkable diversity in form and function. The deep-sea hydrothermal vent limpet Lepetodrilus fucensis from the Juan de Fuca Ridge complex hosts a gill symbiosis of particular interest because it displays a morphology unique among molluscs: filamentous bacteria are found partially embedded in the host's gill epithelium and extend into the fluids circulating across the lamellae. Our objective was to investigate the phylogenetic affiliation of the limpet's primary gill symbionts for comparison with previously characterized bacteria. Comparative 16S rRNA sequence analysis identified one γ- and three ε-Proteobacteria as candidate symbionts. We used fluorescence in situ hybridization (FISH) to test which of these four candidates occur with the limpet's symbiotic gill bacteria. The γ-proteobacterial probes consistently hybridized to the entire area where symbiotic bacteria were found, but fluorescence signal from the ε-proteobacterial probes was generally absent. Amplification of the γ-proteobacterial 16S rRNA gene using a specific forward primer yielded a sequence similar to that of limpets collected from different ridge sections. In total, direct amplification or FISH identified a single γ-proteobacterial lineage from the gills of 23 specimens from vents separated by a distance up to about 200 km and collected over the course of 2 years, suggesting a highly specific and widespread symbiosis. Thus, we report the first filamentous γ-proteobacterial gill symbiont hosted by a mollusc. 相似文献
6.
The marine oligochaete worm Tubificoides benedii is often found in high numbers in eutrophic coastal sediments with low oxygen and high sulfide concentrations. A dense biofilm of filamentous bacteria on the worm's tail end were morphologically described over 20 years ago, but no further studies of these epibiotic associations were done. In this study, we used fluorescence in situ hybridization and comparative sequence analysis of 16S rRNA and protein-coding genes to characterize the microbial community of the worm's tail ends. The presence of genes involved in chemoautotrophy (cbbL and cbbM) and sulfur metabolism (aprA) indicated the potential of the T. benedii microbial community for chemosynthesis. Two filamentous ectosymbionts were specific to the worm's tail ends: one belonged to the Leucothrix mucor clade within the Gammaproteobacteria and the other to the Thiovulgaceae within the Epsilonproteobacteria. Both T. benedii ectosymbionts belonged to clades that consisted almost exclusively of bacteria associated with invertebrates from deep-sea hydrothermal vents. Such close relationships between symbionts from shallow-water and deep-sea hosts that are not closely related to each other are unusual, and indicate that biogeography and host affiliation did not play a role in these associations. Instead, similarities between the dynamic environments of vents and organic-rich mudflats with their strong fluctuations in reductants and oxidants may have been the driving force behind the establishment and evolution of these symbioses. 相似文献
7.
Joseph Selvin R. Gandhimathi G. Seghal Kiran S. Shanmugha Priya T. Rajeetha Ravji T. A. Hema 《Helgoland Marine Research》2009,63(3):239-247
Culturable heterotrophic bacterial composition of marine sponge Dendrilla nigra was analysed using different enrichments. Five media compositions including without enrichment (control), enriched with sponge
extract, with growth regulator (antibiotics), with autoinducers, and complete enrichment containing sponge extract, antibiotics,
and autoinducers were developed. DNA hybridization assay was performed to explore host specific bacteria and ecotypes of culturable
sponge-associated bacteria. Enrichment with selective inducers (AHLs and sponge extract) and regulators (antibiotics) considerably
enhanced the cultivation potential of sponge-associated bacteria. It was found that Marinobacter (MSI032), Micromonospora (MSI033), Streptomyces (MSI051), and Pseudomonas (MSI057) were sponge-associated obligate symbionts. The present findings envisaged that “Micromonospora–Saccharomonospora–Streptomyces” group was the major culturable actinobacteria in the marine sponge D. nigra. The DNA hybridization assay was a reliable method for the analysis of culturable bacterial community in marine sponges.
Based on the culturable community structure, the sponge-associated bacteria can be grouped (ecotypes) as general symbionts,
specific symbionts, habitat flora, and antagonists. 相似文献
8.
Phylogenetic diversity of bacterial symbionts of Solemya hosts based on comparative sequence analysis of 16S rRNA genes. 总被引:1,自引:1,他引:0 下载免费PDF全文
The bacterial endosymbionts of two species of the bivalve genus Solemya from the Pacific Ocean, Solemya terraeregina and Solemya pusilla, were characterized. Prokaryotic cells resembling gram-negative bacteria were observed in the gills of both host species by transmission electron microscopy. The ultrastructure of the symbiosis in both host species is remarkably similar to that of all previously described Solemya spp. By using sequence data from 16S rRNA, the identity and evolutionary origins of the S. terraeregina and S. pusilla symbionts were also determined. Direct sequencing of PCR-amplified products from host gill DNA with primers specific for Bacteria 16S rRNA genes gave a single, unambiguous sequence for each of the two symbiont species. In situ hybridization with symbiont-specific oligonucleotide probes confirmed that these gene sequences belong to the bacteria residing in the hosts gills. Phylogenetic analyses of the 16S rRNA gene sequences by both distance and parsimony methods identify the S. terraeregina and S. pusilla symbionts as members of the gamma subdivision of the Proteobacteria. In contrast to symbionts of other bivalve families, which appear to be monophyletic, the S. terraeregina and S. pusilla symbionts share a more recent common ancestry with bacteria associating endosymbiotically with bivalves of the superfamily Lucinacea than with other Solemya symbionts (host species S. velum, S. occidentalis, and S. reidi). Overall, the 16S rRNA gene sequence data suggest that the symbionts of Solemya hosts represent at least two distinct bacterial lineages within the gamma-Proteobacteria. While it is increasingly clear that all extant species of Solemya live in symbiosis with specific bacteria, the associations appear to have multiple evolutionary origins. 相似文献
9.
Desai MS Strassert JF Meuser K Hertel H Ikeda-Ohtsubo W Radek R Brune A 《Environmental microbiology》2010,12(8):2120-2132
The surface of many termite gut flagellates is colonized with a dense layer of bacteria, yet little is known about the evolutionary relationships of such ectosymbionts and their hosts. Here we investigated the molecular phylogenies of devescovinid flagellates (Devescovina spp.) and their symbionts from a wide range of dry-wood termites (Kalotermitidae). From species-pure flagellate suspensions isolated with micropipettes, we obtained SSU rRNA gene sequences of symbionts and host. Phylogenetic analysis showed that the Devescovina spp. present in many species of Kalotermitidae form a monophyletic group, which includes also the unique devescovinid flagellate Caduceia versatilis. All members of this group were consistently associated with a distinct lineage of Bacteroidales, whose location on the cell surface was confirmed by fluorescence in situ hybridization. The well-supported congruence of the phylogenies of devescovinids and their ectosymbionts documents a strict cospeciation. In contrast, the endosymbionts of the same flagellates ('Endomicrobia') were clearly polyphyletic and must have been acquired independently by horizontal transfer from other flagellate lineages. Also the Bacteroidales ectosymbionts of Oxymonas flagellates present in several Kalotermitidae belonged to several distantly related lines of descent, underscoring the general perception that the evolutionary history of flagellate-bacteria symbioses in the termite gut is complex. 相似文献
10.
Katharina Freyth Tim Janowitz Frank Nunes Melanie Voss Alexander Heinick Joanne Bertaux Stefan Scheu Rüdiger J. Paul 《Molecules and cells》2010,30(4):347-353
Laboratory breeding conditions of the model organism C. elegans do not correspond with the conditions in its natural soil habitat. To assess the consequences of the differences in environmental
conditions, the effects of air composition, medium and bacterial food on reproductive fitness and/or dietary-choice behavior
of C. elegans were investigated. The reproductive fitness of C. elegans was maximal under oxygen deficiency and not influenced by a high fractional share of carbon dioxide. In media approximating
natural soil structure, reproductive fitness was much lower than in s tandard laboratory media. I n seminatural media, the
reproductive fitness of C. elegans was low with the standard laboratory food bacterium E. coli (γ-Proteobacteria), but significantly higher with C. arvensicola (Bacteroidetes) and B. tropica (β-Proteobacteria) as food. Dietary-choice experiments in semi-natural media revealed a low preference of C. elegans for E. coli but significantly higher preferences for C. arvensicola and B. tropica (among other bacteria). Dietary-choice experiments under quasi-natural conditions, which were feasible by fluorescence in situ hybridization (FISH) of bacteria, showed a high preference of C. elegans for Cytophaga-Flexibacter-Bacteroides, Firmicutes, and β-Proteobacteria, but a low preference for γ-Proteobacteria. The results show that data on C. elegans under standard laboratory conditions have to be carefully interpreted with respect to their biological significance. 相似文献
11.
Characterization of chemoautotrophic bacterial symbionts in a gutless marine worm Oligochaeta, Annelida) by phylogenetic 16S rRNA sequence analysis and in situ hybridization. 总被引:7,自引:4,他引:3 下载免费PDF全文
The phylogenetic relationships of chemoautotrophic endosymbionts in the gutless marine oligochaete Inanidrilus leukodermatus to chemoautotrophic ecto- and endosymbionts from other host phyla and to free-living bacteria were determined by comparative 16S rRNA sequence analysis. Fluorescent in situ hybridization confirmed that the 16S rRNA sequence obtained from these worms originated from the symbionts. The symbiont sequence is unique to I. leukodermatus. In phylogenetic trees inferred by both distance and parsimony methods, the oligochaete symbiont is peripherally associated with one of two clusters of chemoautotrophic symbionts that belong to the gamma subdivision of the Proteobacteria. The endosymbionts of this oligochaete form a monophyletic group with chemoautotrophic ectosymbionts of a marine nematode. The oligochaete and nematode symbionts are very closely related, although their hosts belong to separate, unrelated animal phyla. Thus, cospeciation between the nematode and oligochaete hosts and their symbionts could not have occurred. Instead, the similar geographic locations and habitats of the hosts may have influenced the establishment of these symbioses. 相似文献
12.
Ismail M. Al Bulushi Susan Poole Hilton C. Deeth Gary A. Dykes 《World journal of microbiology & biotechnology》2008,24(9):1867-1875
The current study was undertaken to enumerate Gram-positive bacteria in fresh sub-tropical marine fish and determine the effect
of ambient storage (25°C) on the Gram-positive bacterial count. Total and Gram-positive bacteria were enumerated in the muscles,
gills and gut of fresh and stored Pseudocaranx dentex, Pagrus auratus and Mugil cephalus on tryptone soya agar (TSA) and TSA with 0.25% phenylethyl alcohol (PEA), respectively. Initial studies indicated that PEA
significantly reduced total aerobic bacterial count (TABC) whereas control Gram-positive bacteria were not affected by 0.25%
PEA. TABC significantly increased in all fish body parts, whereas Gram-positive aerobic bacterial count (GABC) significantly
increased only in the muscles and gills during ambient storage for 15 h. The TABC of the fish species increased from 4.00,
6.13 and 4.58 log cfu g−1, respectively in the muscles, gills, and gut to 6.31, 7.31 and 7.23 log cfu g−1 by the end of storage. GABC increased from 2.00, 3.52 and 2.20 log cfu g−1 to 4.70, 5.85 and 3.36 log cfu g−1. Within each species, TABC were significantly higher in the gills compared to that of muscles and gut; however, no significant
differences were found in GABC between muscles and gills. This study demonstrated the potential importance of Gram-positive
bacteria in sub-tropical marine fish and their spoilage. 相似文献
13.
Musat N Giere O Gieseke A Thiermann F Amann R Dubilier N 《Environmental microbiology》2007,9(5):1345-1353
Marine nematode worms without a mouth or functional gut are found worldwide in intertidal sandflats, deep-sea muds and methane-rich pock marks, and morphological studies show that they are associated with endosymbiotic bacteria. While it has been hypothesized that the symbionts are chemoautotrophic sulfur oxidizers, to date nothing is known about the phylogeny or function of endosymbionts from marine nematodes. In this study, we characterized the association between bacterial endosymbionts and the marine nematode Astomonema sp. from coral reef sediments in the Bahamas. Phylogenetic analysis of the host based on its 18S rRNA gene showed that Astomonema sp. is most closely related to non-symbiotic nematodes of the families Linhomoeidae and Axonolaimidae and is not closely related to marine stilbonematinid nematodes with ectosymbiotic sulfur-oxidizing bacteria. In contrast, phylogenetic analyses of the symbionts of Astomonema sp. using comparative 16S rRNA gene sequence analysis revealed that these are closely related to the stilbonematinid ectosymbionts (95-96% sequence similarity) as well as to the sulfur-oxidizing endosymbionts from gutless marine oligochaetes. The closest free-living relatives of these gammaproteobacterial symbionts are sulfur-oxidizing bacteria from the family Chromatiaceae. Transmission electron microscopy and fluorescence in situ hybridization showed that the bacterial symbionts completely fill the gut lumen of Astomonema sp., suggesting that these are their main source of nutrition. The close phylogenetic relationship of the Astomonema sp. symbionts to known sulfur-oxidizing bacteria as well as the presence of the aprA gene, typically found in sulfur-oxidizing bacteria, indicates that the Astomonema sp. symbionts use reduced sulfur compounds as an energy source to provide their hosts with nutrition. 相似文献
14.
北极海洋沉积物中锰细菌的分离与系统发育 总被引:2,自引:0,他引:2
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。 相似文献
15.
Most animals harbour symbiotic microorganisms inside their body, where intimate interactions occur between the partners. The medicinal leech, Hirudo verbana, possesses 17 pairs of excretory bladders that harbour a large number of intracellular and extracellular symbiotic bacteria. In this study, we characterized the bladder symbionts using molecular phylogenetic analyses, transmission electron microscopy (TEM) and fluorescence in situ hybridization (FISH). Restriction fragment length polymorphism (RFLP) and sequence analyses of 16S rRNA gene clone libraries suggested that six bacterial species co‐colonize the leech bladders. Phylogenetic analyses revealed that these species belong to the α‐Proteobacteria (Ochrobactrum symbiont), β‐Proteobacteria (Beta‐1 and Beta‐2 symbionts), δ‐Proteobacteria (Bdellovibrio symbiont) and Bacteroidetes (Niabella and Sphingobacterium symbionts). Species‐specific PCR detection and FISH confirmed the localization of the symbiotic bacteria in the bladders. The Ochrobactrum, Beta‐1, Bdellovibrio and Sphingobacterium symbionts were consistently detected in 13 leeches from two populations, while infection rate of the other symbionts ranged between 20% and 100% in the two leech populations. Transmission electron microscopy observations of the bladders revealed epithelial cells harbouring a number of intracellular bacilli and an additional type of extracellular, rod‐shaped bacteria in the luminal region. Fluorescence in situ hybridization with group‐specific oligonucleotide probes revealed the spatial organization of the bacterial species in the bladder: the Ochrobactrum symbiont was located intracellularly inside epithelial cells; the Bacteroidetes were localized close to the epithelium in the lumen of the bladder; and the Bacteroidetes layer was covered with dense β‐proteobacterial cells. These results clearly demonstrate that a simple but organized microbial community exists in the bladder of the medicinal leech. 相似文献
16.
Phylogenetic analysis of a highly specific association between ectosymbiotic, sulfur-oxidizing bacteria and a marine nematode. 总被引:10,自引:5,他引:5 下载免费PDF全文
M F Polz D L Distel B Zarda R Amann H Felbeck J A Ott C M Cavanaugh 《Applied microbiology》1994,60(12):4461-4467
The phylogenetic relationship of chemoautotrophic, sulfur-oxidizing, ectosymbiotic bacteria growing on a marine nematode, a Laxus sp. (formerly a Catanema sp.), to known endosymbionts and free-living bacteria was determined. Comparative 16S rRNA sequencing was used to investigate the unculturable nematode epibionts, and rRNA-targeted oligonucleotide hybridization probes were used to identify the ectosymbionts in situ. Both analyses revealed a remarkably specific and stable symbiosis. Unique hybridization of a specific probe to the ectosymbionts indicated that only one species of bacteria was present and growing on the cuticle of the nematode. Distance and parsimony methods used to infer phylogenetic trees both placed the nematode ectosymbionts at the base of a branch containing chemoautotrophic, sulfur-oxidizing endosymbionts of three bivalve families and of the tube worm Riftia pachyptila. The most closely related free-living bacteria were chemoautotrophic sulfur oxidizers belonging to the genus Thiomicrospira. Furthermore, our results suggested that a second, only distantly related group of thioautotrophic endosymbionts has as its deepest branch surface-colonizing bacteria belonging to the genus Thiothrix, some of which are capable of sulfur-oxidizing chemoautotrophic growth. 相似文献
17.
18.
We examined the species composition of red king crab (Paralithodes camtschaticus) fouling communities in Dolgaya Bay, a small fjord of the Barents Sea, in August 2005 and 2006. In total, there were 13 species
observed on 301 crabs collected from water depths of 5–90 m. Barnacles (Balanus crenatus; prevalence 42.9%) and blue mussels (Mytilus edulis; 11.6%) were the most common epibionts, while amphipods (Ischyrocerus commensalis) were the most common symbionts (28.6%). Infestation rates in Dolgaya Bay were different from those in an “open” area of
the Barents Sea (Dalnezelenetskaya Bay), probably due to differences in hydrodynamic conditions. Differences in infestation
prevalence and intensity were detected neither between male and female crabs nor between crabs collected at 5–35 m versus
90 m depths. Prevalence of common fouling species increased with host size. Amphipods I. commensalis colonized the carapace and limbs in Dolgaya Bay less frequently than in Dalnezelenetskaya Bay, probably due to interspecific
competition with barnacles occupying the dorsal parts of the host. Juvenile barnacles and mussels dominated the fouling communities
on the crabs. The age of barnacles did not exceed 2–4 months. However, the presence of 4-year-old mussels suggests that these
older mollusks have been directly transferred from mussel beds to the hosts. Our results indicate that colonization by epibionts
and symbionts is generally not disadvantageous for the crab hosts, except for some possible negative impacts of amphipods
occupying the gills. 相似文献
19.
Joshi AA Kanekar PP Kelkar AS Shouche YS Vani AA Borgave SB Sarnaik SS 《Microbial ecology》2008,55(2):163-172
Aerobic, alkaliphilic bacteria were isolated and characterized from water and sediment samples collected in the winter season,
January 2002 from alkaline Lonar lake, India, having pH 10.5. The total number of microorganisms in the sediment and water
samples was found to be 102–106 cfu g−1 and 102–104 cfu ml−1, respectively. One hundred and ninety-six strains were isolated using different enrichment media. To study the bacterial
diversity of Lonar lake and to select the bacterial strains for further characterization, screening was done on the basis
of pH and salt tolerance of the isolates. Sixty-four isolates were subjected to phenotypic, biochemical characterization and
16S rRNA sequencing. Out of 64, 31 bacterial isolates were selected on the basis of their enzyme profile and further subjected
to phylogenetic analysis. Phylogenetic analysis indicated that most of the Lonar lake isolates were related to the phylum
Firmicutes, containing Low G+C, Gram-positive bacteria, with different genera: Bacillus, Paenibacillus, Alkalibacillus, Exiguobacterium, Planococcus, Enterococcus and Vagococcus. Seven strains constituted a Gram-negative bacterial group, with different genera: Halomonas, Stenotrophomonas and Providencia affiliated to γ-Proteobacteria, Alcaligenes to β-Proteobacteria and Paracoccus to α-Proteobacteria. Only five isolates were High G+C, Gram-positive bacteria associated with phylum Actinobacteria, with
various genera: Cellulosimicrobium, Dietzia, Arthrobacter and Micrococcus. Despite the alkaline pH of the Lonar lake, most of the strains were alkalitolerant and only two strains were obligate alkaliphilic.
Most of the isolates produced biotechnologically important enzymes at alkaline pH, while only two isolates (ARI 351 and ARI
341) showed the presence of polyhydroxyalkcanoate (PHA) and exopolysaccharide (EPS), respectively. 相似文献
20.
Bacterial Community Diversity in Undisturbed Perhumid Montane Forest Soils in Taiwan 总被引:1,自引:0,他引:1
Yu-Te Lin Yu-Ju Huang Sen-Lin Tang William B. Whitman David C. Coleman Chih-Yu Chiu 《Microbial ecology》2010,59(2):369-378
The diversity and composition of soil bacterial communities in three topographic sites (summit, foot slope, and lakeshore)
from subtropical montane forest ecosystem in Taiwan were examined by using 16S rRNA gene clone library analysis. This locality
is temperate, perhumid, and has low soil acidity (pH < 4), which is an uncommon ecosystem in a monsoonal part of Southeast
Asia. A total of 481 clones were sequenced and placed into ten phylogenetic groups according to their similarities to type
strains of described organisms. Toposequence of the transect was investigated from summit to foot slope and at the lakeshore.
More than 86% of the clones were affiliated with members of the Proteobacteria, Acidobacteria, and Actinobacteria. Within
the Proteobacteria, the β-Proteobacteria was the most abundant, then α-Proteobacteria and γ-Proteobacteria. Based on the Shannon
diversity index (H) analysis, the bacterial community in the foot slope was the most diverse (H = 0.86) and that in summit was the least diverse (H = 0.68). The composition and diversity of soil bacterial communities in the three sites suggested no trend with topographic
change. Less than 20% of the sequences were Acidobacteria-affiliated clones. The low proportion of Acidobacteria observed
may be related to the high soil moisture and anaerobic microhabitats. Moreover, Shannon diversity indices revealed these bacterial
communities to have lower diversity than that of other temperate (H = 0.90) and tropical forest (H = 0.82) ecosystems. The extreme acidity of soil pH and high soil moisture of this forest may explain composition and reduced
the diversity of these soil bacterial communities. 相似文献