Oceanobacillus picturae alleviates cadmium stress and promotes growth in soybean seedlings

Cadmium (Cd) is a heavy metal that significantly impacts human health and the environment. Microorganisms play a crucial role in reducing heavy metal stress in plants; however, the mechanisms by which microorganisms enhance plant tolerance to Cd stress and the interplay between plants and microorganisms under such stress remain unclear. In this study, Oceanobacillus picturae (O. picturae) was isolated for interaction with soybean seedlings under Cd stress. Results indicated that Cd treatment alone markedly inhibited soybean seedling growth. Conversely, inoculation with O. picturae significantly improved growth indices such as plant height, root length, and fresh weight, while also promoting recovery in soil physiological indicators and pH. Metabolomic and transcriptomic analyses identified 157 genes related to aspartic acid, cysteine, and flavonoid biosynthesis pathways. Sixty-three microbial species were significantly associated with metabolites in these pathways, including pathogenic, adversity-resistant, and bioconductive bacteria. This research experimentally demonstrates, for the first time, the growth-promoting effect of the O. picturae strain on soybean seedlings under non-stress conditions. It also highlights its role in enhancing root growth and reducing Cd accumulation in the roots under Cd stress. Additionally, through the utilization of untargeted metabolomics, metagenomics, and transcriptomics for a multi-omics analysis, we investigated the impact of O. picturae on the soil microbiome and its correlation with differential gene expression in plants. This innovative approach unveils the molecular mechanisms underlying O. picturae's promotion of root growth and adaptation to Cd stress.

Effect of ammonia on the active microbiome and metagenome from stable full-scale digesters

Four full-scale anaerobic digesters with a long history of stable operation were characterized in terms of active microbiome and metagenome. Isotopic fractionation of biogas demonstrated that acetotrophy was rather prevalent in reactors operated at <3 gTAN L^-1 while hydrogenotrophy was predominant at >6 gTAN L^-1, suggesting that syntrophic acetate oxidizing bacteria (SAOB) played a significant role in the latter. These results were generally coherent with the observed active bacterial and archaeal communities but no known SAOB were observed. Metagenome descriptions yielded 73 assembled population genomes, of which only 7 could be assigned at the species level. Gene annotation and association to relevant metabolic pathways indicated that the phyla Chloroflexi and Bacteroidales might encompass new, currently undescribed, SAOB/formate producing species that would metabolize acetate via the glycine cleavage system. The predominant hydrogenotrophic counterpart at a high ammonia content belonged to the genus Methanoculleus, which could also grow on acetate to a certain extent.

Emended description of the family Chromatiaceae, phylogenetic analyses of the genera Alishewanella, Rheinheimera and Arsukibacterium, transfer of Rheinheimera longhuensis LH2-2T to the genus Alishewanella and description of Alishewanella alkalitolerans sp. nov. from Lonar Lake, India

Phylogenetic analyses were performed for members of the family Chromatiaceae, signature nucleotides deduced and the genus Alishewanella transferred to Chromatiaceae. Phylogenetic analyses were executed for the genera Alishewanella, Arsukibacterium and Rheinheimera and the genus Rheinheimera is proposed to be split, with the creation of the Pararheinheimera gen. nov. Furthermore, the species Rheinheimera longhuensis, is transferred to the genus Alishewanella as Alishewanella longhuensis comb. nov. Besides, the genera Alishewanella and Rheinheimera are also emended. Strain LNK-7.1^T was isolated from a water sample from the Lonar Lake, India. Cells were Gram-negative, motile rods, positive for catalase, oxidase, phosphatase, contained C_16:0, C_17:1ω8c, summed feature3 (C_16:1ω6c and/or C_16:1ω7c) and summed feature 8 (C_18:1ω7c) as major fatty acids, PE and PG as the major lipids and Q-8 as the sole respiratory quinone. Phylogenetic analyses using NJ, ME, ML and Maximum parsimony, based on 16S rRNA gene sequences, identified Alishewanella tabrizica RCRI4^T as the closely related species of strain LNK-7.1^T with a 16S rRNA gene sequence similarity of 98.13%. The DNA-DNA similarity between LNK-7.1^T and the closely related species (A. tabrizica) was only 12.0% and, therefore, strain LNK-7.1^T was identified as a novel species of the genus Alishewanella with the proposed name Alishewanella alkalitolerans sp. nov. In addition phenotypic characteristics confirmed the species status to strain LNK-7.1^T. The type strain of A. alkalitolerans is LNK-7.1^T (LMG 29592^T = KCTC 52279^T), isolated from a water sample collected from the Lonar lake, India.

Belliella aquatica sp. nov., isolated from a saline lake

A Gram-staining-negative bacterium, strain TS-T86(T), was isolated from Lake Tuosu, a saline lake (salinity 5.4%, w/w) in Qaidam basin, China. Its taxonomic position was determined by using a polyphasic approach. Strain TS-T86(T) was strictly heterotrophic, aerobic and catalase- and oxidase-positive. Cells were non-spore-forming, non-motile rods, 0.4-0.6 µm wide and 1.2-2.3 µm long. Growth was observed in the presence of 0-9.0% (w/v) NaCl (optimum, 2.0%), at 4-35 °C (optimum, 25 °C) and at pH 7.0-10.5 (optimum, pH 8.5-9.0). Strain TS-T86(T) contained MK-7 as the predominant respiratory quinone. The major fatty acids (>10%) were iso-C15 : 1 G, iso-C15 : 0, iso-C17 : 1ω9c, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c). The polar lipids consisted of phosphatidylethanolamine, an unknown phospholipid, six unidentified aminolipids and two uncharacterized lipids. The DNA G+C content was 35 mol% (T m). Phylogenetic trees based on 16S rRNA gene sequences showed that strain TS-T86(T) was associated with the genus Belliella, and showed the highest sequence similarity to Belliella baltica BA134(T) (98.5 %) and then to Belliella kenyensis No.164(T) (95.7%) and Belliella pelovolcani CC-SAL-25(T) (95.3 %). DNA-DNA relatedness of strain TS-T86(T) to Belliella baltica DSM 15883(T) was 32 ± 3%. It is concluded that strain TS-T86(T) represents a novel species of the genus Belliella, for which the name Belliella aquatica sp. nov. is proposed. The type strain is TS-T86(T) ( = CGMCC 1.12479(T) = JCM 19468(T)).

Bacterial tag encoded FLX titanium amplicon pyrosequencing (bTEFAP) based assessment of prokaryotic diversity in metagenome of Lonar soda lake, India

Bacterial diversity and archaeal diversity in metagenome of the Lonar soda lake sediment were assessed by bacterial tag-encoded FLX amplicon pyrosequencing (bTEFAP). Metagenome comprised 5093 sequences with 2,531,282 bp and 53 ± 2% G + C content. Metagenome sequence data are available at NCBI under the Bioproject database with accession no. PRJNA218849. Metagenome sequence represented the presence of 83.1% bacterial and 10.5% archaeal origin. A total of 14 different bacteria demonstrating 57 species were recorded with dominating species like Coxiella burnetii (17%), Fibrobacter intestinalis (12%) and Candidatus Cloacamonas acidaminovorans (11%). Occurrence of two archaeal phyla representing 24 species, among them Methanosaeta harundinacea (35%), Methanoculleus chikugoensis (12%) and Methanolinea tarda (11%) were dominating species. Significant presence of 11% sequences as an unclassified indicated the possibilities for unknown novel prokaryotes from the metagenome.

Belliella kenyensis sp. nov., isolated from an alkaline lake

A red-pigmented, Gram-reaction-negative, aerobic bacterial strain, designated No.164(T), was isolated from sediment sample from the alkaline Lake Elmenteita located in the Kenyan Rift Valley. Results of 16S rRNA gene sequence analysis indicated that the isolate represented a member of the genus Belliella, with the highest sequence similarity (97 %) to Belliella pelovolcani DSM 46698(T). Optimal growth temperature was 30-35 °C, at pH 7.0-12.0 in the presence of 0-4 % (w/v) NaCl. Flexirubins were absent. The respiratory menaquinone (MK-7), predominant cellular fatty acids (iso-C15 : 0, anteiso-C15 : 0 and a mixture of C16 : 1ω7c and/or iso-C15 : 0 2-OH) and DNA G+C content (38.1 mol%) of strain No.164(T) were consistent with those of other members of the genus Belliella. The polar lipids consisted of phosphatidylethanolamine, eight unspecified lipids and one unspecified phospholipid. Several phenotypic characteristics can be used to differentiate this isolate from those of other species of the genus Belliella. The results of polyphasic analyses presented in this study indicated that this isolate should be classified as representing a novel species of the genus Belliella. The name Belliella kenyensis sp. nov. is therefore proposed; the type strain is strain No.164(T) ( = DSM 46651(T) = CECT 8551(T)).

Mariniradius saccharolyticus gen. nov., sp. nov., a member of the family Cyclobacteriaceae isolated from marine aquaculture pond water, and emended descriptions of the genus Aquiflexum and Aquiflexum balticum

A novel marine, Gram-stain-negative, oxidase- and catalase- positive, rod-shaped bacterium, designated strain AK6T, was isolated from marine aquaculture pond water collected in Andhra Pradesh, India. The fatty acids were dominated by iso-C15 : 0, iso-C17 : 1ω9c, iso-C15 : 1 G, iso-C17 : 0 3-OH and anteiso-C15 : 0. Strain AK6T contained MK-7 as the sole respiratory quinone and phosphatidylethanolamine, one unidentified aminophospholipid, one unidentified phospholipid and seven unidentified lipids as polar lipids. The DNA G+C content of strain AK6T was 45.6 mol%. Phylogenetic analysis showed that strain AK6T formed a distinct branch within the family Cyclobacteriaceae and clustered with Aquiflexum balticum DSM 16537T and other members of the family Cyclobacteriaceae . 16S rRNA gene sequence analysis confirmed that Aquiflexum balticum DSM 16537T was the nearest neighbour, with pairwise sequence similarity of 90.1 %, while sequence similarity with the other members of the family was <88.5 %. Based on differentiating phenotypic characteristics and phylogenetic inference, strain AK6T is proposed as a representative of a new genus and species of the family Cyclobacteriaceae , as Mariniradius saccharolyticus gen. nov., sp. nov. The type strain of Mariniradius saccharolyticus is AK6T ( = MTCC 11279T = JCM 17389T). Emended descriptions of the genus Aquiflexum and Aquiflexum balticum are also proposed.

Microbiology of Lonar Lake and other soda lakes

Soda lakes are saline and alkaline ecosystems that are believed to have existed throughout the geological record of Earth. They are widely distributed across the globe, but are highly abundant in terrestrial biomes such as deserts and steppes and in geologically interesting regions such as the East African Rift valley. The unusual geochemistry of these lakes supports the growth of an impressive array of microorganisms that are of ecological and economic importance. Haloalkaliphilic Bacteria and Archaea belonging to all major trophic groups have been described from many soda lakes, including lakes with exceptionally high levels of heavy metals. Lonar Lake is a soda lake that is centered at an unusual meteorite impact structure in the Deccan basalts in India and its key physicochemical and microbiological characteristics are highlighted in this article. The occurrence of diverse functional groups of microbes, such as methanogens, methanotrophs, phototrophs, denitrifiers, sulfur oxidizers, sulfate reducers and syntrophs in soda lakes, suggests that these habitats harbor complex microbial food webs that (a) interconnect various biological cycles via redox coupling and (b) impact on the production and consumption of greenhouse gases. Soda lake microorganisms harbor several biotechnologically relevant enzymes and biomolecules (for example, cellulases, amylases, ectoine) and there is the need to augment bioprospecting efforts in soda lake environments with new integrated approaches. Importantly, some saline and alkaline lake ecosystems around the world need to be protected from anthropogenic pressures that threaten their long-term existence.

Genome sequence of the alkaliphilic bacterium Nitritalea halalkaliphila type strain LW7, isolated from Lonar Lake, India

An alkaliphilic bacterium, Nitritalea halalkaliphila LW7, which belongs to the family Cyclobacteriacae in the phylum Bacteroidetes, was isolated from Lonar Lake in Maharastra, India. Here we announce the draft genome sequence of the type strain LW7, which contains 3,633,701 bp with a G+C content of 48.58%.

Georgenia satyanarayanai sp. nov., an alkaliphilic and thermotolerant amylase-producing actinobacterium isolated from a soda lake

A Gram-stain-positive, oxidase-negative, starch-hydrolysing, actinobacterium (strain JC82T) was isolated from a soda lake in Lonar, India. Based on 16S rRNA gene sequence similarity studies, strain JC82T belonged to the genus Georgenia and was most closely related to Georgenia muralis 1A-CT (96.8 %) and other members of the genus Georgenia (<96.5 %). The DNA G+C content of strain JC82T was 73.4 mol%. The cell-wall amino acids were alanine, glutamic acid and lysine with peptidoglycan type A4α. Polar lipids included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannosides, an unidentified lipid (L1) and an unidentified glycolipid (GL3). The predominant isoprenoid quinone was menaquinone MK-8(H4). Anteiso-C15 : 0 was the predominant fatty acid and significant proportions of iso-C14 : 0, C14 : 0, C16 : 0, iso-C15 : 0 and iso-C16 : 0 were also detected. Strain JC82T produced thermostable alkaline amylase. The results of physiological and biochemical tests allowed a clear phenotypic differentiation of strain JC82T from all other members of the genus Georgenia . Based on these data, strain JC82T represents a novel species of the genus Georgenia , for which the name Georgenia satyanarayanai sp. nov. is proposed. The type strain is JC82T ( = KCTC 19802T = NBRC 107612T).

Cecembia lonarensis gen. nov., sp. nov., a haloalkalitolerant bacterium of the family Cyclobacteriaceae , isolated from a haloalkaline lake and emended descriptions of the genera Indibacter , Nitritalea and Belliella

A novel Gram-staining-negative, rod-shaped, non-motile bacterium, designated strain LW9T, was isolated from a water sample collected from Lonar Lake of Buldhana district, Maharashtra, India. Colonies and broth cultures were reddish orange due to the presence of carotenoid pigments. Strain LW9T was positive for catalase, ornithine decarboxylase and lysine decarboxylase activities and negative for gelatinase, oxidase, urease and lipase activities. The predominant fatty acids were iso-C15 : 0 (31.3 %), iso-C16 : 0 (9.3 %), anteiso-C15 : 0 (7.3 %), iso-C16 : 1 H (6.1 %), summed feature 3 (comprising C16 : 1ω7c/C16 : 1ω6c; 5.9 %), iso-C17 : 1ω9c (5.4 %) and iso-C17 : 0 3-OH (5.0 %). Strain LW9T contained MK-7 as the major respiratory quinone. The polar lipids consisted of phosphatidylethanolamine, two unidentified aminolipids and seven unidentified lipids. The DNA G+C content of strain LW9T was 40.5 mol%. 16S rRNA gene sequence analysis indicated that the type strains of Indibacter alkaliphilus and Aquiflexum balticum , two members of the family Cyclobacteriaceae (phylum ‘ Bacteroidetes ’) were the most closely related strains with sequence similarities of 93.0 and 94.0 %, respectively. Other members of the family Cyclobacteriaceae showed sequence similarities <93.0 %. Based on these phenotypic characteristics and on phylogenetic inference, strain LW9T is proposed as the representative of novel species in a new genus, Cecembia lonarensis gen. nov., sp. nov. The type strain of the type species, Cecembia lonarensis, is LW9T ( = CCUG 58316T = KCTC 22772T). Emended descriptions of the genera Indibacter , Nitritalea and Belliella are also proposed.

Mongoliicoccus roseus gen. nov., sp. nov., an alkaliphilic bacterium isolated from a haloalkaline lake

Two pink, non-motile, aerobic, alkaliphilic, halotolerant, Gram-negative cocci, designated MIM28T and MIM29, were isolated from the surface water of a haloalkaline lake on the Mongolia Plateau. The isolates grew optimally at 30–33 °C, at pH 8–9 and with 3–4 % (w/v) NaCl. The isolates were chemoheterotrophic and could assimilate carbohydrates, organic acids and amino acids. The major respiratory quinone was menaquinone MK-7. The major polar lipids were phosphatidylcholine and phosphatidylethanolamine. The predominant cellular fatty acids were iso-C15 : 0 (13.8–17.5 %), anteiso-C15 : 0 (10.5–11.2 %), iso-C16 : 0 (9.9–13.0 %), C16 : 0 (4.3–4.6 %), iso-C17 : 0 (3.8–5.3 %), anteiso-C17 : 0 (3.7–7.1 %), C17 : 1ω6c (4.6–6.4 %), iso-C17 : 0 3-OH (4.6–5.8 %), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c; 4.0–6.4 %) and summed feature 9 (iso-C17 : 1ω9c and/or C16 : 0 10-methyl; 10.4–12.5 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolates were most closely related to Litoribacter ruber YIM CH208T (93.6 % 16S rRNA gene sequence similarity), the genus Echinicola (90.4–92 %) and other members of the family Cyclobacteriaceae (87.8–90 %). The DNA G+C contents of strains MIM28T and MIM29 were 62.8 and 62.2 mol%. On the basis of morphology, physiology, fatty acid composition, phylogeny and 16S rRNA gene sequence analysis, the isolates are assigned to a novel species of a new genus, for which we propose the name Mongoliicoccus roseus gen. nov., sp. nov.; the type strain of the type species is MIM28T ( = ACCC 05511T  = KCTC 19808T).

Mongoliitalea lutea gen. nov., sp. nov., an alkaliphilic, halotolerant bacterium isolated from a haloalkaline lake

Two bacterial isolates from the surface water of a haloalkaline lake on the Mongolia Plateau, strains MIM18T and MIM19, were characterized; their morphological, physiological and chemotaxonomic characters, and phylogenetic position based on 16S rRNA gene sequences, were determined. The two strains were alkaliphilic, halotolerant, non-motile, aerobic, Gram-negative, orange-red, rod-shaped and oxidase-positive. Growth was observed in 0–5.5 % (w/v) NaCl, with optimum growth at 1 %. The temperature range for growth was 0–41 °C, with good growth at 28–37 °C and optimum growth at 30–33 °C. The DNA G+C content was 39.8–41.2 mol%. The strains contained menaquinone MK-7 as the major respiratory quinone and phosphatidylcholine, phosphatidylglycerol and phosphatidylethanolamine as the major polar lipids. Predominant cellular fatty acids were iso-C15 : 0 (28.1–29.3 %), iso-C17 : 0 3-OH (14.6–18.8 %), C15 : 1ω6c (5.3–8.6 %), C14 : 0 2-OH and/or iso-C15 : 0 2-OH (5.4–6.1 %), and iso-C17 : 1ω9c and/or C16 : 0 10-methyl (5.0–6.8 %). 16S rRNA gene sequence analysis showed that Belliella and Nitritalea of the family Cyclobacteriaceae were the closest related species with sequence similarities of 91.7–92.3 % and 88.2 %, respectively, with strains of these genera; other members of the Cyclobacteriaceae had sequence similarities lower than 88 %. Phylogenetic analysis indicated that the strains formed a deep-rooted lineage distinct from the clades represented by the genera Belliella, Nitritalea, Indibacter, Aquiflexum, Echinicola, Litoribacter, Cyclobacterium and Algoriphagus. Based on the phenotypic and phylogenetic characteristics mentioned above, the two strains are representatives of a single novel species in a new genus; the name Mongoliitalea lutea gen. nov., sp. nov. is proposed, with MIM18T ( = ACCC 05421T = KCTC 23224T) as the type strain.

Litoribacter ruber gen. nov., sp. nov., an alkaliphilic, halotolerant bacterium isolated from a soda lake sediment

A novel alkaliphilic, halotolerant, rod-shaped bacterium, designated strain YIM CH208T, was isolated from a soda lake in Yunnan, south-west China. The taxonomy of strain YIM CH208T was investigated by a polyphasic approach. Strain YIM CH208T was Gram-negative, strictly aerobic and non-motile and formed red colonies. Optimal growth conditions were 28 °C, pH 8.5 and 0.5–2.5 % NaCl. Phylogenetic analysis based on 16S rRNA gene sequence comparisons showed that the isolate formed a distinct line within a clade containing the genus Echinicola in the phylum Bacteroidetes and was related to the species Echinicola pacifica and Rhodonellum psychrophilum, with sequence similarity of 91.7 and 91.6 % to the respective type strains. The DNA G+C content was 45.1 mol%. The major respiratory quinone was menaquinone-7 (MK-7). The predominant cellular fatty acids were iso-C17 : 1 ω9c (19.9 %), C15 : 0 3-OH (12.1 %), iso-C17 : 0 3-OH (11.3 %), summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1 ω7c; 10.7 %) and C17 : 1 ω6c (8.7 %). On the basis of the phenotypic, chemotaxonomic and phylogenetic data, strain YIM CH208T represents a novel species of a new genus, for which the name Litoribacter ruber gen. nov., sp. nov. is proposed. The type strain of Litoribacter ruber is YIM CH208T (=ACCC 05414T =KCTC 22899T).