Composition and diversity of the bacterial community in snow leopard (<Emphasis Type="Italic">Uncia uncia</Emphasis>) distal gut

Intestinal microflora influences many essential metabolic functions, and is receiving increasing attention from the scientific community. However, information on intestinal microbiota, especially for large wild carnivores, is insufficient. In the present study, the bacterial community in the feces of snow leopards (Uncia uncia) was described based on 16S rRNA gene sequence analysis. A total of 339 near-full-length 16S rRNA gene sequences representing 46 non-redundant bacterial phylotypes (operational taxonomical units, OTUs) were identified in fecal samples from four healthy snow leopards. Four different bacterial phyla were identified: Firmicutes (56.5 %), Actinobacteria (17.5 %), Bacteroidetes (13 %), and Proteobacteria (13 %). The phylum Actinobacteria was the most abundant lineage, with 40.4 % of all identified clones, but Clostridiales, with 50 % of all OTUs, was the most diverse bacterial order. The order Clostridiales was affiliated with four families: Clostridiaceae I, Lachnospiraceae, Peptostreptococcaceae, and Ruminococcaceae. Lachnospiraceae was the most diverse family with 17 OTUs identified. These findings were basically consistent with previous reports on the bacterial diversity in feces from other mammals.     

Comparative analysis of prokaryotic diversity in solar salterns in eastern Anatolia (Turkey)

The prokaryotic communities of four salterns (Bingöl, Fadlum, Kemah, and Tuzlagözü) in Turkey were examined and compared using the cultivation and cultivation-independent methods [fluorescence in situ hybridization (FISH) and 454 pyrosequencing]. FISH analysis with universal probes revealed that feeding waters carried 1.6 × 10²–1.7 × 10³ cells mL^?1, while crystallization ponds carried 3.8 × 10⁶–2.0 × 10⁷ cells mL^?1 that were mostly haloarchaea, including square cells (except for Kemah). High-throughput 16S rRNA-based gene sequencing showed that the most frequent archaeal OTUs in Bingöl, Fadlum, Tuzlagözü, and Kemah samples were affiliated with Haloquadratum (76.8 %), Haloarcula (27.8 %), Halorubrum (49.6 %), and Halonotius (59.8 %), respectively. Bacteroidetes was the dominant bacterial phylum in Bingöl and Fadlum, representing 71.5 and 79.5 % of the bacterial OTUs (respectively), while the most abundant bacterial phylum found in the Kemah saltern was Proteobacteria (79.6 %). The majority of the bacterial OTUs recovered from Tuzlagözü belonged to the Cyanobacteria (35.7 %), Bacteroidetes (35.0 %), and Proteobacteria (25.5 %) phyla. Cultivation studies revealed that the archaeal isolates were closely related to the genera Halobacterium, Haloarcula, and Halorubrum. Bacterial isolates were confined to two phyla, Proteobacteria (Alphaproteobacteria and Gammaproteobacteria classes) and Bacteroidetes. Comparative analysis showed that members of the Euryarchaeota, Bacteroidetes, Proteobacteria, and Cyanobacteria phyla were major inhabitants of the solar salterns.     

Epiphytic bacterial communities of the alga <Emphasis Type="Italic">Fucus vesiculosus</Emphasis> in oil-contaminated water areas of the Barents Sea

Taxonomic compositions of epiphytic bacterial communities in water areas differing in levels of oil pollution were revealed. In total, 82 bacterial genera belonging to 16 classes and 11 phyla were detected. All detected representatives of epiphytic bacterial communities belonged to the phyla Actinobacteria, Bacteroidetes, Planctomycetes, Proteobacteria, Verrucomicrobia, Acidobacteria, Cyanobacteria, Firmicutes, and Fusobacteria and candidate division TM7. The ratio of the phyla in the communities varied depending on the levels of oil pollution. New data on taxonomic composition of uncultivated epiphytic bacterial communities of Fucus vesiculosus were obtained.     

Insight into the bacterial diversity of fermentation woad dye vats as revealed by PCR-DGGE and pyrosequencing

The bacterial diversity in fermenting dye vats with woad (Isatis tinctoria L.) prepared and maintained in a functional state for approximately 12 months was examined using a combination of culture-dependent and -independent PCR-DGGE analyses and next-generation sequencing of 16S rRNA amplicons. An extremely complex ecosystem including taxa potentially contributing to both indigo reduction and formation, as well as indigo degradation was found. PCR-DGGE analyses revealed the presence of Paenibacillus lactis, Sporosarcina koreensis, Bacillus licheniformis, and Bacillus thermoamylovorans, while Bacillus thermolactis, Bacillus pumilus and Bacillus megaterium were also identified but with sequence identities lower than 97%. Dominant operational taxonomic units (OTUs) identified by pyrosequencing included Clostridium ultunense, Tissierella spp., Alcaligenes faecalis, Erysipelothrix spp., Enterococcus spp., Virgibacillus spp. and Virgibacillus panthothenicus, while sub-dominant OTUs included clostridia, alkaliphiles, halophiles, bacilli, moderately thermophilic bacteria, lactic acid bacteria, Enterobacteriaceae, aerobes, and even photosynthetic bacteria. Based on the current knowledge of indigo-reducing bacteria, it is considered that indigo-reducing bacteria constituted only a small fraction in the unique microcosm detected in the natural indigo dye vats.     

Structure of Microbial Communities of the Sediments of Alkaline Transbaikalia Lakes with Different Salinity

The goal of the work was to reveal the differences in the structure of microbial communities of Transbaikalia alkaline lakes stemming from the differences in their salinity and hydrochemical parameters. The lakes studied were Verkhnee Beloe (Buryat Republic, Russia), as well as Khilganta, Gorbunka, and Borzinskoe (Transbaikal krai, Russia) with salinity from 12.3 to 430 g/L, which differed in the mineral composition of the sediments and hydrochemical parameters. Lake sediments were found to contain 47 prokaryotic phyla (42 bacterial and 5 archaeal ones). The phyla Proteobacteria, Euryarchaeota, Bacteroides, Chloroflexi, Actinobacteria, and Firmicutes were predominant, comprising over 95% of the classified sequences. Comparative abundance of archaea increased with salinity from below 1% in Lake Verkhnee Beloe to 35% in Lake Borzinskoe. The most numerous bacterial OTUs belonged to gammaproteobacteria of the genus Halomonas (up to 15% of the number of classified sequences). The most numerous archaeal OTUs were identified at the genus level as members of the genera Halorubrum and Halohasta belonging to the family Halorubraceae, which comprises extremely halophilic Euryarchaeota.     

Diversity of Prokaryotes in Planktonic Communities of Saline Sol-Iletsk lakes (Orenburg Oblast,Russia)

Prokaryotic diversity was studied in the planktonic communities of six Sol-Iletsk lakes (Orenburg oblast, Russia) varying in salinity level using the Illumina technology of high-throughput sequencing. The extremely halophilic archaea of the phyla Euryarchaeota and Nanohaloarchaeota, as well as the bacterial phylum Bacteroidetes predominated in the communities of lakes with salinity of 285–300‰. Representatives of the phyla Bacteroidetes and Actinobacteria, as well as of the class Gammaproteobacteria were predominant in the lakes with salinity 110?180‰. A bloom of Cyanobacteria was observed in Bol’shoe Gorodskoe Lake (10‰ salinity). The dominant OTUs in the lakes with high salinity were represented by archaea Halonotius sp., uncultured Nanohaloarchaea, and bacteria Salinibacter sp. In the lakes with medium salinity level the dominants included gammaproteobacteria Spiribacter sp., alphaproteobacteria Roseovarius sp., flavobacteria Psychroflexus sp., unidentified archaea of the family Haloferacaceae, actinobacteria Pontimonas sp. and Rhodoluna sp. In the lake with low salinity level cyanobacteria of the genus Planktothrix were predominant. Effect of salinity on prokaryotic taxonomic richness, composition, and diversity in planktonic communities of the studied lakes was demonstrated.     

Illumina-based analysis of the rhizosphere microbial communities associated with healthy and wilted Lanzhou lily (<Emphasis Type="Italic">Lilium davidii</Emphasis> var. <Emphasis Type="Italic">unicolor</Emphasis>) plants grown in the field

Lanzhou lily (Liliumdavidii var. unicolor) is the best edible lily as well as a traditional medicinal plant in China. The microbes associated with plant roots play crucial roles in plant growth and health. However, little is known about the differences of rhizosphere microbes between healthy and wilted Lanzhou lily (Lilium davidii var. unicolor) plants. The objective of this study was to compare the rhizosphere microbial community and functional diversity of healthy and wilted plants, and to identify potential biocontrol agents with significant effect. Paired end Illumina Mi-Seq sequencing of 16S rRNA and ITS gene amplicons was employed to study the bacterial and fungal communities in the rhizosphere soil of Lanzhou lily plants. BIOLOG technology was adopted to investigate the microbial functional diversity. Our results indicated that there were major differences in the rhizosphere microbial composition and functional diversity of wilted samples compared with healthy samples. Healthy Lanzhou lily plants exhibited lower rhizosphere-associated bacterial diversity than diseased plants, whereas fungi exhibited the opposite trend. The dominant phyla in both the healthy and wilted samples were Proteobacteria and Ascomycota, i.e., 34.45 and 64.01 %, respectively. The microbial functional diversity was suppressed in wilted soil samples. Besides Fusarium, the higher relative abundances of Rhizoctonia, Verticillium, Penicillium, and Ilyonectria (Neonectria) in the wilted samples suggest they may pathogenetic root rot fungi. The high relative abundances of Bacillus in Firmicutes in healthy samples may have significant roles as biological control agents against soilborne pathogens. This is the first study to find evidence of major differences between the microbial communities in the rhizospheric soil of healthy and wilted Lanzhou lily, which may be linked to the health status of plants.     

Distribution of sediment bacterial and archaeal communities in plateau freshwater lakes

Both Bacteria and Archaea might be involved in various biogeochemical processes in lacustrine sediment ecosystems. However, the factors governing the intra-lake distribution of sediment bacterial and archaeal communities in various freshwater lakes remain unclear. The present study investigated the sediment bacterial and archaeal communities in 13 freshwater lakes on the Yunnan Plateau. Quantitative PCR assay showed a large variation in bacterial and archaeal abundances. Illumina MiSeq sequencing illustrated high bacterial and archaeal diversities. Bacterial abundance was regulated by sediment total organic carbon and total nitrogen, and water depth, while nitrate nitrogen was an important determinant of bacterial diversity. Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, Chlorobi, Chloroflexi, Cyanobacteria, Firmicutes, Gemmatimonadetes, Nitrospirae, Planctomycetes, and Verrucomicrobia were the major components of sediment bacterial communities. Proteobacteria was the largest phylum, but its major classes and their proportions varied greatly among different lakes, affected by sediment nitrate nitrogen. In addition, both Euryarchaeota and Crenarchaeota were important members in sediment archaeal communities, while unclassified Archaea usually showed the dominance.     

Structure and diversity of bacterial communities in the fermentation of da-jiang

Da-jiang is the traditional soybean fermented food which is popular in the world for a long time. In order to improve the quality and nutritional value of da-jiang, structure and diversity of bacterial communities in the fermentation of da-jiang were analyzed. Illumina MiSeq platforms coupled with bioinformatics approach were used in this study. In the first 28 days, the trends of bacterial abundance were similar in different regions which are increasing firstly, decreasing secondly, and rising again. The quantity of bacteria in post-fermentation is lower than pre-fermentation. In the fermentation of da-jiang, Firmicutes and Proteobacteria are the dominant phyla. The dominant genera in da-jiang from different regions are different: Tetragenococcus (58.1–73.0%) is the dominant genus in da-jiang from Xinmin; Leuconostoc (9.2–25.7%) is the dominant genus in da-jiang from Tieling; Acinetobacter (8.7–25.1%) and Leuconostoc (12.4–22.0%) are the dominant genera in da-jiang from Shenyang. Additionally, Weissella, Lactobacillus, Staphylococcus, Erwinia, and Pseudomonas also were found in da-jiang. It is identified that Leuconostoc steadily existed in all da-jiang samples. These results demonstrate the diversity of microbes in traditional fermented da-jiang, which will probably provide a data basis for choosing starter culture for da-jiang industrial fermentation.     

Characterization of bacterial composition and diversity in a long-term petroleum contaminated soil and isolation of high-efficiency alkane-degrading strains using an improved medium

Bacterial community and diversity in a long-term petroleum-contaminated soil of an oilfield were characterized using 16S rRNA gene-based Illumina MiSeq high-throughput sequencing. Results indicated that Proteobacteria (49.11%) and Actinobacteria (24.24%) were the most dominant phyla, and the most abundant genera were Pseudoxanthomonas (8.47%), Luteimonas (3.64%), Alkanindiges (9.76%), Acinetobacter (5.26%) and Agromyces (8.56%) in the soil. Meanwhile a series of cultivations were carried out for isolation of alkane degraders from petroleum-contaminated soil with gellan gum and agar as gelling agents. And the isolates were classified by their 16S rRNA genes. Nine of the isolates including Enterobacter, Pseudomonas,Acinetobacter, Rhizobium, Bacillus, Sphingomonas, Paenibacillus, Variovorax and Rhodococcus showed strong biodegradability of alkane mixture (C9–C30) in a wide range of chain-length, which could be potentially applied in enhancement of bioremediation.     

Effects of diet type,developmental stage,and gut compartment in the gut bacterial communities of two <Emphasis Type="Italic">Cerambycidae species</Emphasis> (Coleoptera)

The gut bacterial community of wood-feeding beetles has been examined for its role on plant digestion and biocontrol method development. Monochamus alternatus and Psacothea hilaris, both belonging to the subfamily Lamiinae, are woodfeeding beetles found in eastern Asia and Europe and generally considered as destructive pests for pine and mulberry trees, respectively. However, limited reports exist on the gut bacterial communities in these species. Here, we characterized gut bacterial community compositions in larva and imago of each insect species reared with host tree logs and artificial diets as food sources. High-throughput 454 pyrosequencing of bacterial 16S rRNA gene revealed 225 operational taxonomic units (OTUs) based on a 97% sequences similarity cutoff from 138,279 sequence reads, the majority of which were derived from Proteobacteria (48.2%), Firmicutes (45.5%), and Actinobacteria (5.2%). The OTU network analysis revealed 7 modules with densely connected OTUs in specific gut samples, in which the distributions of Lactococcus-, Kluyvera-, Serratia-, and Enterococcus-related OTUs were distinct between diet types or developmental stages of the host insects. The gut bacterial communities were separated on a detrended correspondence analysis (DCA) plot and by c-means fuzzy clustering analysis, according to diet type. The results from this study suggest that diet was the main determinant for gut bacterial community composition in the two beetles.     

Characterization of Bacterial Communities in Deep-Sea Hydrothermal Vents from Three Oceanic Regions

Deep-sea hydrothermal vents are considered to be one of the most spectacular ecosystems on Earth. Microorganisms form the basis of the food chain in vents controlling the vent communities. However, the diversity of bacterial communities in deep-sea hydrothermal vents from different oceans remains largely unknown. In this study, the pyrosequencing of 16S rRNA gene was used to characterize the bacterial communities of the venting sulfide, seawater, and tubeworm trophosome from East Pacific Rise, South Atlantic Ridge, and Southwest Indian Ridge, respectively. A total of 23,767 operational taxonomic units (OTUs) were assigned into 42 different phyla. Although Proteobacteria, Actinobacteria, and Bacteroidetes were the predominant phyla in all vents, differences of bacterial diversity were observed among different vents from three oceanic regions. The sulfides of East Pacific Rise possessed the most diverse bacterial communities. The bacterial diversities of venting seawater were much lower than those of vent sulfides. The symbiotic bacteria of tubeworm Ridgeia piscesae were included in the bacterial community of vent sulfides, suggesting their significant ecological functions as the primary producers in the deep-sea hydrothermal vent ecosystems. Therefore, our study presented a comprehensive view of bacterial communities in deep-sea hydrothermal vents from different oceans.     

Microbial diversity of the Soldhar hot spring,India, assessed by analyzing 16S rRNA and protein-coding genes

Bacterial diversity of the Soldhar hot spring, located in the Chamoli district of Uttarakhand, India, was investigated using a clone library, denaturing gradient gel electrophoresis (DGGE) and functional genes. Physicochemical analysis of sediment samples indicated an oligotrophic environment with very low sulfur content. Based on the 16S rRNA gene studies Proteobacteria was the most predominant group in all the three approaches. Other dominant phyla were Deinococcus-Thermus and Aquificae. Pyrobaculum was the only archaeal genus detected by DGGE. In the functional gene analysis, the nifH library showed a single operational taxonomic unit (OTU) related to the genus Paenibacillus whereas the aoxB library showed three OTUs related to Acidovorax, Aminobacter and Agrobacterium. Our results demonstrate for the first time both the bacterial and archaeal diversity in the Soldhar hot spring by culture-independent techniques, thereby providing important information that will increase our understanding of the microbial ecology of the Soldhar hot spring.     

Dynamics and diversity of a microbial community during the fermentation of industrialized <Emphasis Type="Italic">Qingcai</Emphasis> paocai,a traditional Chinese fermented vegetable food,as assessed by Illumina MiSeq sequencing,DGGE and qPCR assay

Paocai is a traditional Chinese fermented food and typically produced via spontaneous fermentation. We have investigated the microbial community utilized for the fermentation of industrialized Qingcai paocai using the combination of Illumina MiSeq sequencing, PCR-mediated denaturing gradient gel electrophoresis (PCR-DGGE) and quantitative PCR (qPCR) assay. Three main phyla, namely Firmicutes, Proteobacteria and Bacteroidetes, were identified by both MiSeq sequencing and PCR-DGGE. The dominant genera observed in the fermentation were Lactobacillus, Pseudomonas, Vibrio and Halomonas. Most genera affiliated with Proteobacteria or Bacteroidetes were detected more often during the earlier part of the fermentation, while Lactobacillus (affiliated with Firmicutes) was dominant during the later fermentation stages. Fungal community analysis revealed that Debaryomyces, Pichia and Kazachstania were the main fungal genera present in industrialized Qingcai paocai, with Debaryomyces being the most dominant during the fermentation process. The quantities of dominant genera Lactobacillus and Debaryomyces were monitored using qPCR and shown to be 10⁹–10¹² and 10⁶–10¹⁰ copies/mL, respectively. During the later fermentation process of industrialized Qingcai paocai, Lactobacillus and Debaryomyces were present at 10¹¹ and 10⁸ copies/mL, respectively. These results facilitate further understanding of the unique microbial ecosystem during the fermentation of industrialized Qingcai paocai and guide future improvement of the fermentation process.     

Bacterial diversity obtained by culturable approaches in the gut of <Emphasis Type="Italic">Glossina pallidipes</Emphasis> population from a non sleeping sickness focus in Tanzania: preliminary results

Background

Glossina pallidipes is a haematophagous insect that serves as a cyclic transmitter of trypanosomes causing African Trypanosomiasis (AT). To fully assess the role of G. pallidipes in the epidemiology of AT, especially the human form of the disease (HAT), it is essential to know the microbial diversity inhabiting the gut of natural fly populations. This study aimed to examine the diversity of G. pallidipes fly gut bacteria by culture-dependent approaches.

Results

113 bacterial isolates were obtained from aerobic and anaerobic microorganisms originating from the gut of G. pallidipes. 16S rDNA of each isolate was PCR amplified and sequenced. The overall majority of identified bacteria belonged in descending order to the Firmicutes (86.6%), Actinobacteria (7.6%), Proteobacteria (5.5%)and Bacteroidetes (0.3%). Diversity of Firmicutes was found higher when enrichments and isolation were performed under anaerobic conditions than aerobic ones. Experiments conducted in the absence of oxygen (anaerobiosis) led to the isolation of bacteria pertaining to four phyla (83% Firmicutes, 15% Actinobacteria, 1% Proteobacteria and 0.5% Bacteroidetes, whereas those conducted in the presence of oxygen (aerobiosis) led to the isolation of bacteria affiliated to two phyla only (90% Firmicutes and 10% Proteobacteria). Phylogenetic analyses placed these isolates into 11 genera namely Bacillus, Acinetobacter, Mesorhizobium, Paracoccus, Microbacterium, Micrococcus, Arthrobacter, Corynobacterium, Curtobacterium, Vagococcus and Dietzia spp.which are known to be either facultative anaerobes, aerobes, or even microaerobes.

Conclusion

This study shows that G. pallidipes fly gut is an environmental reservoir for a vast number of bacterial species, which are likely to be important for ecological microbial well being of the fly and possibly on differing vectorial competence and refractoriness against AT epidemiology.

     

Prokaryotic diversity in a Tunisian hypersaline lake,Chott El Jerid

Prokaryotic diversity was investigated in a Tunisian salt lake, Chott El Jerid, by quantitative real-time PCR, denaturing gradient gel electrophoresis (DGGE) fingerprinting methods targeting the 16S rRNA gene and culture-dependent methods. Two different samples S1-10 and S2-10 were taken from under the salt crust of Chott El Jerid in the dry season. DGGE analysis revealed that bacterial sequences were related to Firmicutes, Proteobacteria, unclassified bacteria, and Deinococcus-Thermus phyla. Anaerobic fermentative and sulfate-reducing bacteria were also detected in this ecosystem. Within the domain archaea, all sequences were affiliated to Euryarchaeota phylum. Quantitative real-time PCR showed that 16S rRNA gene copy numbers of bacteria was 5 × 10⁶ DNA copies g^?1 whereas archaea varied between 5 × 10⁵ and 10⁶ DNA copies g^?1 in these samples. Eight anaerobic halophilic fermentative bacterial strains were isolated and affiliated with the species Halanaerobium alcaliphilum, Halanaerobium saccharolyticum, and Sporohalobacter salinus. These data showed an abundant and diverse microbial community detected in the hypersaline thalassohaline environment of Chott El Jerid.     

Evaluation of the Diversity of Probiotic <Emphasis Type="Italic">Bacillus</Emphasis>, <Emphasis Type="Italic">Clostridium</Emphasis>, and <Emphasis Type="Italic">Bifidobacterium</Emphasis> Using the Illumina-Based Sequencing Method

Bacterial species of Bacillus, Lactobacillus, and Bifidobacterium in the intestinal tract have been used as probiotics. Selections for probiotic candidates by the culture-based approaches are time-consuming and labor-consuming. The aim of this study was to develop a new method based on sequencing strategies to select the probiotic Bacillus, Lactobacillus, and Bifidobacterium. The Illumina-based sequencing strategies with different specific primers for Bacillus, Clostridium, and Bifidobacterium were applied to analyze diversity of the genera in goat feces. The average number of different Bacillus, Clostridium, and Bifidobacterium OTUs (operational taxonomic units) at the 97% similarity level ranged from 1922 to 63172. The coverage index values of Bacillus, Clostridium, and Bifidobacterium calculated from the bacterial OTUs were 0.89, 0.99, and 1.00, respectively. The most genera of Bacillus (37.9%), Clostridium (53%), and Bifidobacterium (99%) were detected in goat feces by the Illumina-based sequencing with the specific primers of the genera, respectively. Higher phylogenetic resolutions of the genera in goat feces were successfully established. The results suggest that the selection for probiotic Bacillus, Clostridium, and Bifidobacterium based on the Illumina sequencing with their specific primers is reliable and feasible, and the core Bacillus, Clostridium, and Bifidobacterium species of healthy goats possess the potentials as probiotic microbial consortia.     

Description of Freshwater Bacterial Assemblages from the Upper Paraná River Floodpulse System,Brazil

Bacteria were identified from a large, seasonally flooded river (Paraná River, Brazil) and two floodplain habitats that were part of the same river system yet very different in nature: clearwater Garças Lagoon and the highly humic waters of Patos Lagoon. Bacterioplankton were collected during mid-summer (Jan. 2002) from water samples (2 l) filtered first through a 1.2-μm filter then a 0.2-μm membrane filter representing the particle-attached and free-living sub-communities, respectively. DNA was extracted from filters and purified and a 16S rRNA clone library established for each habitat. Over 300 clones were sequenced and checked for similarity to existing 16S sequences in GenBank using the BLAST algorithm with default parameters. Further classification of clones was done using a species “backbone” attachment followed by parsimony analysis. The majority (85%) of sequences, referred to here as operational taxonomic units (OTUs), were most similar to uncultured bacterium 16S sequences. OTUs from each Proteobacteria sub-phylum (α, β, γ, δ, ?) were present in the Upper Paraná River system, as well as members of the Bacteroidetes. The microbial assemblage from Patos Lagoon was least like other samples in that it had no Firmicutes present and was dominated by Actinobacteria. Verrucomicrobia OTUs were only found in the free-living assemblage. This study documents the presence of globally distributed phyla in Upper Paraná River and taxa unique to habitat and particle attachment.     

Impact of soil salinity on the microbial structure of halophyte rhizosphere microbiome

The rhizosphere microbiome plays a significant role in the life of plants in promoting plant survival under adverse conditions. However, limited information is available about microbial diversity in saline environments. In the current study, we compared the composition of the rhizosphere microbiomes of the halophytes Urochloa, Kochia, Salsola, and Atriplex living in moderate and high salinity environments (Khewra salt mines; Pakistan) with that of the non-halophyte Triticum. Soil microbiomes analysis using pyrosequencing of 16S rRNA gene indicated that Actinobacteria were dominant in saline soil samples whereas Proteobacteria predominated in non-saline soil samples. Firmicutes, Acidobacteria, Bacteriodetes and Thaumarchaeota were predominant phyla in saline and non-saline soils, whereas Cyanobacteria, Verrucomicrobia, Gemmatimonadetes and the unclassified WPS-2 were less abundant. Sequences from Euryarchaeota, Ignavibacteriae, and Nanohaloarchaeota were identified only from the rhizosphere of halophytes. Dominant halophilic bacteria and archaea identified in this study included Agrococcus, Armatimonadetes gp4, Halalkalicoccus, Haloferula and Halobacterium. Our analysis showed that increases in soil salinity correlated with significant differences in the alpha and beta diversity of the microbial communities across saline and non-saline soil samples. Having a complete inventory of the soil bacteria from different saline environments in Pakistan will help in the discovery of potential inoculants for crops growing on salt-affected land.