Rhizobium acaciae sp. nov., a new nitrogen-fixing symbiovar isolated from root nodules of Acacia saligna in Tunisia.

Three bacterial strains, 1AS11T, 1AS12 and 1AS13, members of the new symbiovar salignae and isolated from root nodules of Acacia saligna grown in Tunisia, were characterized using a polyphasic approach. All three strains were assigned to the Rhizobium leguminosarum complex on the basis of rrs gene analysis. Phylogenetic analysis based on 1734 nucleotides of four concatenated housekeeping genes (recA, atpD, glnII and gyrB) showed that the three strains were distinct from known rhizobia species of the R. leguminosarum complex and clustered as a separate clade within this complex. Phylogenomic analysis of 92 up-to-date bacterial core genes confirmed the unique clade. The digital DNA-DNA hybridization and blast-based average nucleotide identity values for the three strains and phylogenetically related Rhizobium species ranged from 35.9 to 60.0% and 87.16 to 94.58 %, which were lower than the 70 and 96% species delineation thresholds, respectively. The G+C contents of the strains were 60.82-60.92 mol% and the major fatty acids (>4 %) were summed feature 8 (57.81 %; C18 : 1 ω7c) and C18 : 1 ω7c 11-methyl (13.24%). Strains 1AS11T, 1AS12 and 1AS13 could also be differentiated from their closest described species (Rhizobium indicum, Rhizobium laguerreae and Rhizobium changzhiense) by phenotypic and physiological properties as well as fatty acid content. Based on the phylogenetic, genomic, physiological, genotypic and chemotaxonomic data presented in this study, strains 1AS11T, 1AS12 and 1AS13 represent a new species within the genus Rhizobium and we propose the name Rhizobium acaciae sp. nov. The type strain is 1AS11T (=DSM 113913T=ACCC 62388T).

Prokaryotic communities adapted to microhabitats on the Indian lotus (Nelumbo nucifera) growing in the high-altitude urban Dal Lake.

Indian lotus (Nelumbo nucifera) is one of the dominant aquatic plants cultivated in Dal Lake, situated at 1586 m above mean sea level (MSL) in the northeast of Srinagar, Kashmir. Despite their economic and ecological role, the microbial communities associated with the lotus plant are still unexplored. In this study, we investigated the prokaryotic communities on surfaces of different lotus microhabitats (roots, rhizome, leaves, flowers, and fruits), lake water, and sediments using 16S rRNA gene amplicon sequencing. Overall, prokaryotic diversity decreased significantly on the surface of lotus microhabitats in comparison to the lake water and sediments. Among the microhabitats of lotus, roots and leaves harbored more diverse communities in comparison to rhizomes, fruits, and flowers. A total of 98 genera were shared by lotus and the Dal Lake sediments and water. However, significant differences were found in their relative abundance; for example, Pseudomonas was the most dominant genus on the majority of lotus microhabitats. On the other hand, Flavobacterium was highly abundant in the lake water, while a higher abundance of Acinetobacter was recorded in sediments. Additionally, we also noted the presence of potential human pathogenic genera including Escherichia-Shigella, Enterobacter, Pantoea, Raoultella, Serratia, and Sphingomonas on the lotus microhabitats. Predicted functions of prokaryotic communities revealed a higher abundance of genes associated with nutrient uptake in the microhabitats of the lotus. This study offered first-hand information on the prokaryotic communities harbored by lotus plants and water and sediments of the Dal Lake and demonstrated the adaptation of diverse communities to microhabitats of lotus.

Quorum sensing activities and genomic insights of plant growth-promoting rhizobacteria isolated from Assam tea.

Secretion of quorum sensing (QS) molecules is important for the effective colonization of host plants by plant growth-promoting rhizobacteria. The current study aims at the isolation and characterization of tea rhizo bacteria, which produce the QS molecules, acyl homoserine lactone (AHLs), along with multiple plant growth-promoting (PGP) activities. Thirty-one isolates were isolated from the tea rhizosphere, and screening for PGP activities resulted in the selection of isolates RTE1 and RTE4 with multiple PGP traits, inhibiting the growth of tea fungal pathogens. Both isolates also showed production of AHL molecules when screened using two biosensor strains, Chromobacterium violaceum CV026 and Escherichia coli MT 102(jb132). The isolates identified as Burkholderia cepacia RTE1 and Pseudomonas aeruginosa RTE4 based on genome-based analysis like phylogeny, dDDH, and fastANI calculation. Detailed characterization of AHLs produced by the isolates using reverse-phase TLC, fluorometry, and LC-MS indicated that the isolate RTE1 produced a short chain, C8, and a long chain C12 AHL, while RTE4 produced short-chain AHLs C4 and C6. Confocal microscopy revealed the formation of thick biofilm by RTE1 and RTE4 (18 and 23 µm, respectively). Additionally, we found several genes involved in QS, and PGP, inducing systemic resistance (ISR) activities such as lasI/R, qscR, pqq, pvd, aldH, acdS, phz, Sod, rml, and Pch, and biosynthetic gene clusters like N-acyl homoserine lactone synthase, terpenes, pyochelin, and pyocyanin. Based on the functional traits like PGP, biofilm formation and production of AHL molecules, and genetic potential of the isolates B. cepacia RTE1 and P. aeruginosa RTE4 appear promising candidates to improve the health and growth of tea plantations.

Peteryoungia gen. nov. with four new species combinations and description of Peteryoungia desertarenae sp. nov., and taxonomic revision of the genus Ciceribacter based on phylogenomics of Rhizobiaceae.

A novel bacterial strain designated as ADMK78T was isolated from the saline desert soil. The cells were rod-shaped, Gram-stain-negative, and non-motile. The strain ADMK78T grows best at 28 °C. Phylogeny of 16S rRNA gene placed the strain ADMK78T with the members of genera Ciceribacter and Rhizobium, while the highest sequence similarity was with Rhizobium wuzhouense W44T (98.7%) and Rhizobium ipomoeae shin9-1 T (97.9%). Phylogenetic analysis based on 92 core-genes extracted from the genome sequences and average amino acid identity (AAI) revealed that the strain ADMK78T forms a distinct cluster including five species of Rhizobium, which is separate from the cluster of the genera Rhizobium and Ciceribacter. We propose re-classification of Rhizobium ipomoeae, R. wuzhouense, R. rosettiformans and R. rhizophilum into the novel genus Peteryoungia. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values of ADMK78T were less than 82 and 81%, respectively, among all type strains included in the genus Peteryoungia. The strain ADMK78T showed differences in physiological, phenotypic, and protein profiles estimated by MALDI-TOF MS to its closest relatives. Based on the phenotypic, chemotaxonomic properties, and phylogenetic analyses, the strain ADMK78T represents a novel species, Peteryoungia desertarenae sp. nov. The type strain is ADMK78T (= MCC 3400T; KACC 21383T; JCM 33657T). We also proposed the reclassification of Rhizobium daejeonense, R. naphthalenivorans and R. selenitireducens, into the genus Ciceribacter, based on core gene phylogeny and AAI values.

Klebsiella indica sp. nov., isolated from the surface of a tomato.

A novel bacterial strain, designated TOUT106T, was isolated from the surface of a tomato. The cells were rod-shaped, Gram-negative, encapsulated and non-motile. Strain TOUT106T grows best at 28 °C and pH 7.0 and can tolerate up to 2 % (w/v) NaCl. Based on 16S rRNA gene phylogeny, strain TOUT106T was placed close to the Salmonella clade, with close similarity to Salmonella enterica subsp. arizonae strain NCTC 8297T (98.42 %). Results of genome-based phylogenetic analysis revealed that strain TOUT106T is placed well in the Klebsiella-Raoultella clade, by forming a distinct branch with Klebsiella michiganensis DSM25444T, Klebsiella oxytoca NCTC132727T, Klebsiella grimontii 06D021T and Klebsiella pasteurii SB6412T. The genomic DNA G+C content of strain TOUT106T is 53.53 mol%. The average nucleotide identity values of TOUT106T were less than 86.5 % with closely related members of the family Enterobacteriaceae. The major fatty acids of strain TOUT106T were C16 : 0, C17:0 cyclo, C14:0 3OH/C16:1 iso, C14 : 0, C19:0 cyclo ω8c, C18:1 ω6c/C18:1 ω7c, C12 : 0 and C16:1 ω7c/C16:1 ω6c. Strain TOUT106T showed differences in physiological, phenotypic and protein profiles by MALDI-TOF MS compared to its closest relatives. Based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, strain TOUT106T could be distinguished from the recognized species of the genus Klebsiella. It is suggested to represent a novel species of this genus, for which the name Klebsiella indica sp. nov. is proposed. The type strain is TOUT106T (=MCC 2901T=KACC 21384T=JCM 33718T).

Bacterial Communities Associated with the Biofilms Formed in High-Altitude Brackish Water Pangong Tso Located in the Himalayan Plateau.

Pangong Tso is a long and narrow lake situated at an altitude of ~ 4266 m amsl in the Himalayan Plateau on the side of the India/China border. Biofilm has been observed in a small area near the shore of Pangong Tso. Bacterial communities of the lake sediment, water and biofilms were studied using amplicon sequencing of V3-V4 region of the 16S rRNA gene. The standard QIIME pipeline was used for analysis. The metabolic potential of the community was predicted using functional prediction tool Tax4Fun. Bacterial phyla Proteobacteria, followed by Bacteroidetes, Acidobacteria, Planctomycetes, Actinobacteria, and Firmicutes, were found to be dominant across these samples. Shannon's and Simpson's alpha diversity analysis revealed that sediment communities are the most diverse, and water communities are the least diverse. Principal Coordinates based beta diversity analysis showed significant variation in the bacterial communities of the water, sediment and biofilm samples. Bacterial phyla Verrucomicrobia, Deinococcus-Thermus and Cyanobacteria were explicitly enriched in the biofilm samples. Predictive functional profiling of these bacterial communities showed a higher abundance of genes involved in photosynthesis, biosynthesis of secondary metabolites, carbon fixation in photosynthetic organisms and glyoxylate and dicarboxylate metabolism in the biofilm sample. In conclusion, the Pangong Tso bacterial communities are quite similar to other saline and low-temperature lakes in the Tibetan Plateau. Bacterial community structure of the biofilm samples was significantly different from that of the water and sediment samples and enrichment of saprophytic communities was observed in the biofilm samples, indicating an important succession event in this high-altitude lake.

Subsaxibacter sediminis sp. nov., isolated from Arctic glacial sediment and emended description of the genus Subsaxibacter.

A Gram-stain-negative, yellowish-orange pigmented, rod-shaped, motile bacterium, designated strain ARC111T, was isolated from sediment of Arctic permafrost at Midtre Lovénbreen glacier, Svalbard. 16S rRNA gene based identification of strain ARC111T demonstrated highest sequence similarities to Subsaxibacter broadyi P7T (97.8 %) and Subsaxibacter arcticus JCM30334T (97.5 %) and ≤95.2 % with all other members of the family Flavobacteriaceae. Phylogenetic analysis revealed the distinct positioning of strain ARC111T within the genus Subsaxibacter. The G+C content of ARC111T was 37.8±0.5 mol% while DNA-DNA hybridization depicted 35.6 % relatedness with S. arcticus JCM30334T. Strain ARC111T had C15 : 0iso, C16 : 0iso 3-OH, C15 : 1iso G, C15 : 0anteiso, C16 : 1iso H and C17 : 0iso 3-OH as major (>5 % of the total) cellular fatty acids and MK-6 was the predominant respiratory quinone. The polar lipid profile of strain ARC111T consisted of phosphatidylethanolamine, aminolipid and an unidentified lipid. Strain ARC111T harboured sym-homospermidine as the major polyamine. Characteristic differences obtained using polyphasic analysis of strain ARC111T and its closest relatives suggested that strain ARC111T is a novel species of genus Subsaxibacter, for which the name Subsaxibacter sediminis sp. nov. has been proposed. The type strain is ARC111T (=MCC 3191T=KCTC 42965T=LMG 29783T=GDMCC 1.1201T).

Microbacterium telephonicum sp. nov., isolated from the screen of a cellular phone.

A cultivation-based study of the microbial diversity of cellular phone screens led to the isolation of a Gram-stain-positive, aerobic, rod-shaped and non-endospore-forming bacterium, designated S2T63T, exhibiting phenotypic and genotypic characteristics unique to the type strains of closely related species. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain is a member of Microbacterium, and most closely related to Microbacterium aurantiacum IFO 15234T and Microbacterium kitamiense Kitami C2T. The DNA-DNA relatedness values of the strain S2T63T to M. aurantiacum KACC 20510T, M. kitamiense KACC 20514Tand Microbacterium laevaniformans KACC 14463T were 65 % (±4), 29.5 % (±3) and 55.9 % (±4), respectively. The genomic DNA G+C content was 71.8 mol%. The major fatty acids were anteiso-C15 : 0, iso-C16 : 0, C16 : 0 and anteiso-C17 : 0. The main polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and two unidentified polar lipids. The peptidoglycan contained the amino acids glycine, lysine, alanine and glutamic acid, with substantial amounts of hydroxy glutamic acid detected, which is characteristic of peptidoglycan type B1α. The predominant menaquinones were MK-12 and MK-13. Rhamnose, fucose and galactose were the whole-cell sugars detected. The strain also showed biofilm production, estimated by using crystal violet assay. Based on the results of the phenotypic and genotypic characterizations, it was concluded that the new strain represents a novel species of the genus Microbacterium, for which the name Microbacteriumtelephonicum is proposed, with S2T63T (=MCC 2967T=KACC 18715T=LMG 29293T) as the type strain.

Description of Lysinibacillus telephonicus sp. nov., isolated from the screen of a cellular phone.

A novel bacterial strain, designated S5H2222T, was isolated form the screen of a cellular phone. The cells were Gram-stain-positive, rod-shaped, aerobic and motile, and endospores are formed. S5H2222T grew as pale white colonies on trypticase soy agar and the best growth was observed at 37 °C (10-55 °C) and at pH 7.0 (5.0-9.0). S5H2222T could tolerate up to 10 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences placed this strain within the genus Lysinibacillus and it exhibited high 16S rRNA gene sequence similarity to Lysinibacillus halotolerans LAM612T (97.8 %), Lysinibacillus chungkukjangi 2RL3-2T (97.4 %) and Lysinibacillus sinduriensis BLB-1T (97.2 %). The DNA-DNA relatedness of the strain with L. halotolerans JCM 19611T, L. chungkukjangi KACC 16626T and L. sinduriensis KACC 16611T was 57, 64 and 55 % respectively. The genomic DNA G+C content was 39.8 mol%. The major fatty acids of S5H2222T were iso-C15 : 0, anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. MK-7 was the only menaquinone and the main polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine, four unidentified polar lipids were also present. The diagnostic amino acids in the cell wall peptidoglycan contained Lys-Asp (type A4α). On the basis of the results of the phenotypic and genotypic characterizations, it was concluded that S5H2222T represents a novel species of the genus Lysinibacillus, for which the name Lysinibacillus telephonicus sp. nov. is proposed. The type strain is S5H2222T (=MCC 3065T=KACC 18714T=LMG 29294T).

Reclassification of Phycicola gilvus (Lee et al. 2008) and Leifsonia pindariensis (Reddy et al. 2008) as Microterricola gilva comb. nov. and Microterricola pindariensis comb. nov. and emended description of the genus Microterricola.

The taxonomic positions of Microterricola viridarii JCM 15926T, Phycicola gilvus DSM 18319T and Leifsonia pindariensis JCM 15132T were re-examined. Phylogenetic analysis and 16S rRNA gene sequence similarities revealed that all three strains are closely related with each other and form a monophyletic cluster with high sequence similarity (99.2 -99.9 %). A dendrogram constructed based on the protein spectra generated by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy also displayed close clustering of these three strains. The fatty acid profiles of three strains were very similar to each other and contained branched fatty acids (anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0) as the predominant cellular fatty acids. The polar lipid profiles of the three stains were similar and consisted of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylcholine as major polar lipids and an unknown lipid. Comparisons of morphological, chemotaxonomic and physiological data of Microterricola viridarii JCM 15926T, Leifsonia pindariensis JCM 15132T and Phycicola gilvus DSM 18319T are in agreement with the features of a common genus. DNA-DNA hybridization data generated during this study showed less than 70 % reassociation value with each other indicating that they are different at species level. Based on the present study, we conclude that Phycicola gilvus DSM 18319T and Leifsonia pindariensis JCM 15132T should be reclassified under the genus Microterricola, since this genus has the nomenclatural priority, and reclassified as Microterricolagilva comb. nov. (type strain SSWW-21T=DSM 18319T=KCTC 19185T=JCM 30550T) and Microterricolapindariensis comb. nov. (type strain PON10T=LMG 24222T=JCM 15132T=MTCC9128T). An emended description of the genus Microterricola is also presented.

Statistical Optimization of Medium Components for Mass Production of Plant Growth-Promoting Microbial Inoculant Pseudomonas trivialis BIHB 745 (MTCC5336).

Optimizing nutritional requirements for mass production of microbial inoculants in shortened time has relevance for their economical field application. Therefore, the present study aimed at selecting suitable growth medium, optimizing its components, and up-scaling inoculum production for plant growth-promoting Pseudomonas trivialis BIHB 745. Of the different media tested, the culture exhibited maximal viable colony count in trypticase soya broth with 17.6 % increased biomass on optimizing levels of carbon source, nitrogen source, and NaCl using response surface methodology. A twofold higher biomass with 9 h shorter incubation period was obtained in optimized medium in a bioreactor in comparison to shake flasks.

Genome sequence-based identification of Enterobacter strains and description of Enterobacter pasteurii sp. nov.

IMPORTANCE: Accurate taxonomy is essential for microbial biological resource centers, since the microbial resources are often used to support new discoveries and subsequent research. Here, we used genome sequence data, alongside matrix-assisted laser desorption/ionization time-of-flight mass spectrometer biotyper-based protein profiling, to accurately identify six Enterobacter cloacae complex strains. This approach effectively identified distinct species within the E. cloacae complex, including Enterobacter asburiae, "Enterobacter xiangfangensis," and Enterobacter quasihormaechei. Moreover, the study revealed the existence of a novel species within the Enterobacter genus, for which we proposed the name Enterobacter pasteurii sp. nov. In summary, this study demonstrates the significance of adopting a genome sequence-driven taxonomy approach for the precise identification of bacterial strains in a biological resource center and expands our understanding of the E. cloacae complex.

Traditional uses, phytochemistry, pharmacology, and toxicology of the genus Artemisia L. (Asteraceae): A high-value medicinal plant.

Biologically active secondary metabolites, essential oils, and volatile compounds derived from medicinal and aromatic plants play a crucial role in promoting human health. Within the large family Asteraceae, the genus Artemisia consists of approximately 500 species. Artemisia species have a rich history in traditional medicine worldwide, offering remedies for a wide range of ailments, such as malaria, jaundice, toothache, gastrointestinal problems, wounds, inflammatory diseases, diarrhoea, menstrual pains, skin disorders, headache, and intestinal parasites. The therapeutic potential of Artemisia species is derived from a multitude of phytoconstituents, including terpenoids, phenols, flavonoids, coumarins, sesquiterpene lactones, lignans, and alkaloids that serve as active pharmaceutical ingredients (API). The remarkable antimalarial, antimicrobial, anthelmintic, antidiabetic, anti-inflammatory, anticancer, antispasmodic, antioxidative and insecticidal properties possessed by the species are attributed to these APIs. Interestingly, several commercially utilized pharmaceutical drugs, including arglabin, artemisinin, artemether, artesunate, santonin, and tarralin have also been derived from different Artemisia species. However, despite the vast medicinal potential, only a limited number of Artemisia species have been exploited commercially. Further, the available literature on traditional and pharmacological uses of Artemisia lacks comprehensive reviews. Therefore, there is an urgent need to bridge the existing knowledge gaps and provide a scientific foundation for future Artemisia research endeavours. It is in this context, the present review aims to provide a comprehensive account of the traditional uses, phytochemistry, documented biological properties and toxicity of all the species of Artemisia and offers useful insights for practitioners and researchers into underutilized species and their potential applications. This review aims to stimulate further exploration, experimentation and collaboration to fully realize the therapeutic potential of Artemisia in augmenting human health and well-being.

A genetic discontinuity in root-nodulating bacteria of cultivated pea in the Indian trans-Himalayas.

Evolutionary relationships of 120 root-nodulating bacteria isolated from the nodules of Pisum sativum cultivated at 22 different locations of the trans-Himalayan valleys of Lahaul and Spiti in the state of Himachal Pradesh of India were studied using 16S rRNA gene PCR-RFLP, ERIC-PCR, sequencing of 16S rRNA, atpD, recA, nodC and nifH genes, carbon-source utilization pattern (BIOLOG™), and whole-cell fatty acid profiling. The results demonstrated that all isolates belonged to Rhizobium leguminosarum symbiovar viciae (Rlv). Isolates from the two valleys were clearly separated on the basis of ERIC fingerprints, carbon-source utilization pattern, and whole-cell fatty acid methyl esters. Phylogenetic analysis of atpD, recA, nodC and nifH genes revealed a common Rlv sublineage in Spiti valley. Lahaul valley isolates were represented by three sequence types of atpD and recA genes, and four sequence types of nodC and nifH genes. Genotypes from the two valleys were completely distinct, except for two Lahaul isolates that shared nodC and nifH sequences with Spiti isolates but were otherwise more similar to other Lahaul isolates. Isolates from the two highest Spiti valley sites (above 4000 m) had a distinctive whole-cell fatty acid profile. Spiti valley isolates are closely related to Rlv sublineages from Xinjiang and Shanxi provinces in China, while Lahaul valley isolates resemble cosmopolitan strains of the western world. The high mountain pass between these valleys represents a boundary between two distinct microbial populations.

In vitro Sequestration of Molecular and Mass Spectra Characterized Metallophilic Cadmium Tolerant Bacteria for Sustainable Agriculture.

Due to industrialization, the contamination of toxic metals in soils is currently one of the major concerns to scientists worldwide. The presence of high concentrations of heavy metals including cadmium in the environment is mainly attributed to human activities. Being a highly toxic metal, cadmium can enter plant cell transporters usually used for the uptake of essential cations, such as iron, calcium, and zinc. This study deals with the appraisement of response and tolerance shown by various bacteria in varied cadmium concentrations (100-1,000 ppm). The optical density (OD) of the isolates was measured to determine the minimum inhibitory concentration (MIC) of cadmium. Isolated bacteria have been identified using 16S rRNA gene sequence and Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Among the 72 isolates, 07 (Bacillus pumilus, Enterobacter kobei, Klebsiella pneumonia, Pseudomonas mandelii, Pseudomonas putida, Pseudomonas avellanae, and Staphylococcus equorum), isolates had efficacy for cadmium tolerance and showed sequestration potential at varying MIC. Furthermore, K. pneumonia was observed to have the highest (900 ppm) tolerance for cadmium and the lowest (600 ppm) was shown by E. kobei. Besides, K. pneumonia showed the highest (75.2%) sequestration potential while the least (52.4%) potential was observed for P. putida. These cadmium tolerant species can be implemented in contaminated environments for detoxification and elimination of cadmium from these agricultural fields. Graphical Abstract.

Phylogenetic diversity and plant growth-promoting activities of rhizobia nodulating fenugreek (Trigonella foenum-graecum Linn.) cultivated in different agroclimatic regions of India.

Fenugreek (Trigonella foenum-graecum Linn.), is an extensively cultivated legume crop used as a herb, spice, and traditional medicine in India. The symbiotic efficiency and plant growth-promoting potential of fenugreek rhizobia depend on the symbiont strain and environmental factors. We isolated 176 root-nodulating bacteria from fenugreek cultivated in different agroclimatic regions of India. MALDI-TOF MS-based identification and phylogenetic analyses based on 16S rRNA and five housekeeping genes classified the fenugreek-rhizobia as Ensifer (Sinorhizobium) meliloti. However, the strains represent separate sub-lineages of E. meliloti, distinct from all reported sub-lineages across the globe. We also observed the spatial distribution of fenugreek rhizobia, as the three sub-lineages of E. meliloti recorded during this study were specific to their respective agroclimatic regions. According to the symbiotic gene (nodC and nifH) phylogenies, all three sub-lineages of E. meliloti harboured symbiotic genes similar to symbiovar meliloti; as with the housekeeping genes, these also revealed a spatial distribution for different clades of sv. meliloti. The strains could nodulate fenugreek plants and they showed plant growth-promoting potential. Significant differences were found in the plant growth parameters in response to inoculation with the various strains, suggesting strain-level differences. This study demonstrates that fenugreek rhizobia in India are diverse and spatially distributed in different agro-climatic regions.

Genomic Insights into Omega-3 Polyunsaturated Fatty Acid Producing Shewanella sp. N2AIL from Fish Gut.

The genus Shewanella is widely distributed in niches ranging from an aquatic environment to spoiled fish and is loaded with various ecologically and commercially important metabolites. Bacterial species under this genus find application in bioelectricity generation and bioremediation due to their capability to use pollutants as the terminal electron acceptor and could produce health-beneficial omega-3 fatty acids, particularly eicosapentaenoic acid (EPA). Here, the genome sequence of an EPA-producing bacterium, Shewanella sp. N2AIL, isolated from the gastrointestinal tract of Tilapia fish, is reported. The genome size of the strain was 4.8 Mb with a GC content of 46.3% containing 4385 protein-coding genes. Taxonogenomic analysis assigned this strain to the genus Shewanella on the basis of average nucleotide identity (ANI) and in silico DNA-DNA hybridization (DDH), phylogenetically most closely related with S. baltica NCTC 10735T. The comparative genome analysis with the type strain of S. baltica revealed 693 unique genes in the strain N2AIL, highlighting the variation at the strain level. The genes associated with stress adaptation, secondary metabolite production, antibiotic resistance, and metal reduction were identified in the genome suggesting the potential of the bacterium to be explored as an industrially important strain. PUFA synthase gene cluster of size ~20.5 kb comprising all the essential domains for EPA biosynthesis arranged in five ORFs was also identified in the strain N2AIL. The study provides genomic insights into the diverse genes of Shewanella sp. N2AIL, which is particularly involved in adaptation strategies and prospecting secondary metabolite potential, specifically the biosynthesis of omega-3 polyunsaturated fatty acids.

Valorization Potential of a Novel Bacterial Strain, Bacillus altitudinis RSP75, towards Lignocellulose Bioconversion: An Assessment of Symbiotic Bacteria from the Stored Grain Pest, Tribolium castaneum.

Bioconversion of lignocellulose into renewable energy and commodity products faces a major obstacle of inefficient saccharification due to its recalcitrant structure. In nature, lignocellulose is efficiently degraded by some insects, including termites and beetles, potentially due to the contribution from symbiotic gut bacteria. To this end, the presented investigation reports the isolation and characterization of cellulolytic bacteria from the gut system of red flour beetle, Tribolium castaneum. Out of the 15 isolated bacteria, strain RSP75 showed the highest cellulolytic activities by forming a clearance zone of 28 mm in diameter with a hydrolytic capacity of ~4.7. The MALDI-TOF biotyping and 16S rRNA gene sequencing revealed that the strain RSP75 belongs to Bacillus altitudinis. Among the tested enzymes, B. altitudinis RSP75 showed maximum activity of 63.2 IU/mL extract for xylanase followed by ß-glucosidase (47.1 ± 3 IU/mL extract) which were manifold higher than previously reported activities. The highest substrate degradation was achieved with wheat husk and corn cob powder which accounted for 69.2% and 54.5%, respectively. The scanning electron microscopy showed adhesion of the bacterial cells with the substrate which was further substantiated by FTIR analysis that depicted the absence of the characteristic cellulose bands at wave numbers 1247, 1375, and 1735 cm-1 due to hydrolysis by the bacterium. Furthermore, B. altitudinis RSP75 showed co-culturing competence with Saccharomyces cerevisiae for bioethanol production from lignocellulose as revealed by GC-MS analysis. The overall observations signify the gut of T. castaneum as a unique and impressive reservoir to prospect for lignocellulose-degrading bacteria that can have many biotechnological applications, including biofuels and biorefinery.

Defining the Rhizobium leguminosarum Species Complex.

Bacteria currently included in Rhizobium leguminosarum are too diverse to be considered a single species, so we can refer to this as a species complex (the Rlc). We have found 429 publicly available genome sequences that fall within the Rlc and these show that the Rlc is a distinct entity, well separated from other species in the genus. Its sister taxon is R. anhuiense. We constructed a phylogeny based on concatenated sequences of 120 universal (core) genes, and calculated pairwise average nucleotide identity (ANI) between all genomes. From these analyses, we concluded that the Rlc includes 18 distinct genospecies, plus 7 unique strains that are not placed in these genospecies. Each genospecies is separated by a distinct gap in ANI values, usually at approximately 96% ANI, implying that it is a 'natural' unit. Five of the genospecies include the type strains of named species: R. laguerreae, R. sophorae, R. ruizarguesonis, "R. indicum" and R. leguminosarum itself. The 16S ribosomal RNA sequence is remarkably diverse within the Rlc, but does not distinguish the genospecies. Partial sequences of housekeeping genes, which have frequently been used to characterize isolate collections, can mostly be assigned unambiguously to a genospecies, but alleles within a genospecies do not always form a clade, so single genes are not a reliable guide to the true phylogeny of the strains. We conclude that access to a large number of genome sequences is a powerful tool for characterizing the diversity of bacteria, and that taxonomic conclusions should be based on all available genome sequences, not just those of type strains.