Optimization of Cellulase Production by Cohnella xylanilytica RU-14 Using Statistical Methods

In this study, the cellulase activity by bacterial strain Cohnella xylanilytica RU-14 was enhanced by optimizing the medium components using statistical methods of Plackett-Burman design (PBD) and response surface methodology-central composite design (RSM-CCD). The cellulase assay was performed using NS enzyme assay method for reducing sugars. By PBD, the most significant factors (CMC, pH, and yeast extract) in an enzyme production medium that influence cellulase production by RU-14 were identified. These identified significant variables were further optimized using RSM by CCD. It was found that under optimized conditions of the medium components, the cellulase activity increased three times up to 14.5 U/mL as compared to un-optimized conditions (5.2 U/mL) of the enzyme production medium. The optimized levels of the significant factors determined by the CCD were found to be CMC, 2.3% w/v, and yeast extract, 0.75% w/v, at pH 7.5. The most adequate temperature for cellulase production by the bacterial strain was found to be 37 °C using the one-factor-at-a-time method. Thus, statistical methods to optimize medium conditions to enhance cellulase production by Cohnella xylanilytica RU-14 were found successful.

Identification of a novel xanthan-binding module of a multi-modular Cohnella sp. xanthanase

A new strain of xanthan-degrading bacteria identified as Cohnella sp. has been isolated from a xanthan thickener for food production. The strain was able to utilize xanthan as the only carbon source and to reduce the viscosity of xanthan-containing medium during cultivation. Comparative analysis of the secretomes of Cohnella sp. after growth on different media led to the identification of a xanthanase designated as CspXan9, which was isolated after recombinant production in Escherichia coli. CspXan9 could efficiently degrade the β-1,4-glucan backbone of xanthan after previous removal of pyruvylated mannose residues from the ends of the native xanthan side chains by xanthan lyase treatment (XLT-xanthan). Compared with xanthanase from Paenibacillus nanensis, xanthanase CspXan9 had a different module composition at the N- and C-terminal ends. The main putative oligosaccharides released from XLT-xanthan by CspXan9 cleavage were tetrasaccharides and octasaccharides. To explore the functions of the N- and C-terminal regions of the enzyme, truncated variants lacking some of the non-catalytic modules (CspXan9-C, CspXan9-N, CspXan9-C-N) were produced. Enzyme assays with the purified deletion derivatives, which all contained the catalytic glycoside hydrolase family 9 (GH9) module, demonstrated substantially reduced specific activity on XLT-xanthan of CspXan9-C-N compared with full-length CspXan9. The C-terminal module of CspXan9 was found to represent a novel carbohydrate-binding module of family CBM66 with binding affinity for XLT-xanthan, as was shown by native affinity polyacrylamide gel electrophoresis in the presence of various polysaccharides. The only previously known binding function of a CBM66 member is exo-type binding to the non-reducing fructose ends of the β-fructan polysaccharides inulin and levan.

Disturbance-diversity relationships of microbial communities change based on growth substrate

Disturbance events can impact ecological community dynamics. Understanding how communities respond to disturbances and how those responses can vary is a challenge in microbial ecology. In this study, we grew a previously enriched specialized microbial community on either cellulose or glucose as a sole carbon source and subjected them to one of five different disturbance regimes of varying frequencies ranging from low to high. Using 16S rRNA gene amplicon sequencing, we show that the community structure is largely driven by substrate, but disturbance frequency affects community composition and successional dynamics. When grown on cellulose, bacteria in the genera Cellvibrio, Lacunisphaera, and Asticcacaulis are the most abundant microbes. However, Lacunisphaera is only abundant in the lower disturbance frequency treatments, while Asticcacaulis is more abundant in the highest disturbance frequency treatment. When grown on glucose, the most abundant microbes are two Pseudomonas sequence variants and a Cohnella sequence variant that is only abundant in the highest disturbance frequency treatment. Communities grown on cellulose exhibited a greater range of diversity (1.95-7.33 Hill 1 diversity) that peaks at the intermediate disturbance frequency treatment or one disturbance every 3 days. Communities grown on glucose, however, ranged from 1.63 to 5.19 Hill 1 diversity with peak diversity at the greatest disturbance frequency treatment. These results demonstrate that the dynamics of a microbial community can vary depending on substrate and the disturbance frequency and may potentially explain the variety of diversity-disturbance relationships observed in microbial systems.IMPORTANCEA generalizable diversity-disturbance relationship (DDR) of microbial communities remains a contentious topic. Various microbial systems have different DDRs. Rather than finding support or refuting specific DDRs, we investigated the underlying factors that lead to different DDRs. In this study, we measured a cellulose-enriched microbial community's response to a range of disturbance frequencies from high to low, across two different substrates: cellulose and glucose. We demonstrate that the community displays a unimodal DDR when grown on cellulose and a monotonically increasing DDR when grown on glucose. Our findings suggest that the same community can display different DDRs. These results suggest that the range of DDRs we observe across different microbial systems may be due to the nutritional resources microbial communities can access and the interactions between bacteria and their environment.

Description and genomic characterization of Cohnella caldifontis sp. nov., isolated from hot springs in Yunnan province, south-west China

A bacterial strain, Gram staining positive, strictly aerobic, rod-shaped, motile bacterium with flagellum and endospore-forming, designated strain YIM B05605T, was isolated from soil sampled in Hamazui hot springs, Tengchong City, Yunnan province, China. Optimum growth for the strain occurred at pH 7.0 and 45 °C. MK-7 was the main menaquinone in the strain YIM B05605T. The diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. Diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylmonomethylethanolamine (PME), unidentified glycolipid (GL), three unknown aminophospholipids (APLs) and unidentified polarlipid (PL) were part of the polar lipid profile. The major fatty acids were anteiso-C15:0 and iso-C16:0. The DNA G + C content of the type strain was 58.76%. Genome-based phylogenetic analysis confirmed that strain YIM B05605T formed a distinct phylogenetic cluster within the genus Cohnella. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values of strain YIM B05605T with the most related species C. fontinalis YT-1101T were 73.42% and 15.7%. Functional analysis by NR, Swiss-prot, Pfam, eggNOG, GO, KEGG databases revealed that strain YIM B05605T has 13 genes related to the sulfur cycle, 2 genes related to the nitrogen cycle. Based on phylogenomic and phylogenetic analyses coupled with phenotypic and chemotaxonomic characterizations, strain YIM B05605T could be classified as a novel species of the genus Cohnella, for which the name Cohnella caldifontis sp. nov., is proposed. The type strain is YIM B05605T (= CGMCC 1.60052T = KCTC 43462T = NBRC 115921T).

Pan-Genome Analyses of the Genus Cohnella and Proposal of the Novel Species Cohnella silvisoli sp. nov., Isolated from Forest Soil

Two strains, designated NL03-T5T and NL03-T5-1, were isolated from a soil sample collected from the Nanling National Forests, Guangdong Province, PR China. The two strains were Gram-stain-positive, aerobic, rod-shaped and had lophotrichous flagellation. Strain NL03-T5T could secrete extracellular mucus whereas NL03-T5-1 could not. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the two strains belong to the genus Cohnella, were most closely related to Cohnella lupini LMG 27416T (95.9% and 96.1% similarities), and both showed 94.0% similarity with Cohnella arctica NRRL B-59459T, respectively. The two strains showed 99.8% 16S rRNA gene sequence similarity between them. The draft genome size of strain NL03-T5T was 7.44 Mbp with a DNA G+C content of 49.2 mol%. The average nucleotide identities (ANI) and the digital DNA-DNA hybridization (dDDH) values between NL03-T5T and NL03-T5-1 were 99.98% and 100%, indicating the two strains were of the same species. Additionally, the ANI and dDDH values between NL03-T5T and C. lupini LMG 27416T were 76.1% and 20.4%, respectively. The major cellular fatty acids of strain NL03-T5T included anteiso-C15:0 and iso-C16:0. The major polar lipids and predominant respiratory quinone were diphosphatidylglycerol (DPG) and menaquinone-7 (MK-7). Based on phylogenetic analysis, phenotypic and chemotaxonomic characterization, genomic DNA G+C content, and ANI and dDDH values, strains NL03-T5T and NL03-T5-1 represent novel species in the genus Cohnella, for which the name Cohnella silvisoli is proposed. The type strain is NL03-T5T (=GDMCC 1.2294T = JCM 34999T). Furthermore, comparative genomics revealed that the genus Cohnella had an open pan-genome. The pan-genome of 29 Cohnella strains contained 41,356 gene families, and the number of strain-specific genes ranged from 6 to 1649. The results may explain the good adaptability of the Cohnella strains to different habitats at the genetic level.

Disturbance-Diversity Relationships of Microbial Communities Change Based on Growth Substrate

Disturbance events can impact ecological community dynamics. Understanding how communities respond to disturbances, and how those responses can vary, is a challenge in microbial ecology. In this study, we grew a previously enriched specialized microbial community on either cellulose or glucose as a sole carbon source, and subjected them to one of five different disturbance regimes of varying frequencies ranging from low to high. Using 16S rRNA gene amplicon sequencing, we show that community structure is largely driven by substrate, but disturbance frequency affects community composition and successional dynamics. When grown on cellulose, bacteria in the genera Cellvibrio, Lacunisphaera, and Asticaccacaulis are the most abundant microbes. However, Lacunisphaera is only abundant in the lower disturbance frequency treatments, while Asticaccaulis is more abundant in the highest disturbance frequency treatment. When grown on glucose, the most abundant microbes are two Pseudomonas sequence variants, and a Cohnella sequence variant that is only abundant in the highest disturbance frequency treatment. Communities grown on cellulose exhibited a greater range of diversity (0.67-1.99 Shannon diversity and 1.38-5.25 Inverse Simpson diversity) that peak at the intermediate disturbance frequency treatment, or 1 disturbance every 3 days. Communities grown on glucose, however, ranged from 0.49-1.43 Shannon diversity and 1.37- 3.52 Inverse Simpson with peak diversity at the greatest disturbance frequency treatment. These results demonstrate that the dynamics of a microbial community can vary depending on substrate and the disturbance frequency, and may potentially explain the variety of diversity-disturbance relationships observed in microbial ecosystems.

Cohnella herbarum sp. nov., isolated from wild grass fermentation broth

A novel strictly aerobic, Gram-stain-positive, rod-shaped, motile, endospore-forming, white-coloured bacterium, designated strain MFER-1T, was isolated from a fermented liquor of wild grasses sampled in the Republic of Korea. The respiratory quinone of strain MFER-1T was menaquinone-7 and its major cellular fatty acids were anteiso-C15 : 0 (55.3 %), iso-C16 : 0 (17.5 %) and C16 : 0 (12.1 %). The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, four unidentified aminophospholipids and an unidentified phospholipid. The 16S rRNA gene sequence of strain MFER-1T showed similarity of 98.1 % to ‘Cohnella cholangitidis’ 1 605-214T and below 98.0 % sequence similarity to the other Cohnella species. The phylogenomic tree indicated that strain MFER-1T formed a reliable cluster with several Cohnella species. The estimated genome size of strain MFER-1T was 8.52 Mb. Genomic DNA G+C content was 50.7mol%. The orthologous average nucleotide identity, digital DNA–DNA hybridization and amino acid identity values of strain MFER-1T with the most closely related species ‘Cohnella cholangitidis’ 1 605-214T were 78.7, 23.0 and 79.6 %, respectively. Based on the phenotypic, chemotaxonomic and phylogenetic results, strain MFER-1T should represent a novel species of the genus Cohnella , for which the name Cohnella herbarum sp. nov. is proposed, with strain MFER-1T (=KACC 21 257T=NBRC 114 628T) as the type strain.

Cohnella cholangitidis sp. nov., a novel species of the genus Cohnella isolated from a clinical specimen in Korea

A Gram-positive, aerobic, rod-shaped bacterium, designated as strain 1605-214^T, was isolated from the blood sample of a patient with cholangitis. Based on its 16S rRNA gene sequence, the strain 1605-214^T belonged to the genus Cohnella and exhibited 97.9% sequence identity with Cohnella luojiensis DSM 24270^T (GQ214052). DNA–DNA hybridization, digital DNA–DNA hybridization, and average nucleotide identity values between the two species were 23% ± 1.9, 21.1%, and 77.2%, respectively. The cellular fatty acids of strain 1605-214^T were mainly comprised of anteiso-C_15:0 (36.1%), iso-C_16:0 (16.5%), and C_16:0 (15.1%). The predominant quinone was menaquinone-7; predominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, and aminophospholipid-1. The cell wall peptidoglycan of strain 1605-214^T contained meso-diaminopimelic acid. DNA G + C content of strain 1605-214^T was 50.6 mol%. 5187 genes out of a total of 5413 (94.6%) were assigned putative functions using eggNOG v5.0. Based on genotypic characteristics and genomic sequence analysis results, strain 1605-214^T was confirmed to represent a novel species of genus Cohnella, for which the name Cohnella cholangitidis sp. nov., was proposed.

Cohnella terricola sp. nov., isolated from soil

A Gram-positive, aerobic, flagellated, endospore-forming, rod-shaped strain, designated as G13^T, was isolated from soil. The results of 16S rRNA gene sequence analysis led to the conclusion that strain G13^T was phylogenetically related to Cohnella boryungensis BR29^T (97.5 %) and Cohnella phaseoli CECT 7287^T (96.9 %) with digital DNA-DNA hybridization values of 21.0 and 21.4 %, and distantly related to Cohnella thermotolerans CCUG 47242^T (94.8 %), type species of the genus Cohnella, at 19.0 %. The genome size of strain G13^T was 5 387 258 bp, with 51.3 mol% G+C content. The predominant fatty acids were summed feature 9 (iso-C_17 : 1  ω9c and/or C_16 : 0 10-methyl), anteiso-C_17 : 0, iso-C_17 : 0 and iso-C_15 : 0. The predominant quinone was menaquinone-7 and the major polar lipids were diphosphatidyglycerol, phosphatidylethanolamine, phosphatidylglycerol, lysylphosphatidylglycerol, three aminophospholipids, two phosphoglycolipids, three aminolipids and two unidentified lipids. Based on the data from phenotypic tests and the genotypic differences between strain G13^T and its close phylogenetic relatives, strain G13^T represents a new species belonging to the genus Cohnella, for which the name Cohnella terricola sp. nov. (=KACC 19905^T=NBRC 113748^T) is proposed.

Cohnella pontilimi sp. nov., isolated from tidal-flat mud

A Gram-positive, aerobic, endospore-forming, rod-shaped bacterial strain, CAU 1483 ^T, was isolated from tidal-flat mud in the Republic of Korea. It grew optimally at 30 °C, in a pH 7.0 medium with 2% (w/v) NaCl. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain CAU 1483 ^T formed a separate clade within Paenibacillaceae together with members of the genus Cohnella. Strain CAU 1483 ^T exhibited the highest 16S rRNA gene sequence similarity (97.1%) to C. candidum 18JY8-7 ^T. Whole genome of strain CAU 1483 ^T was 4.29 Mb in size with a 53.7 mol% G + C content, and included 4046 coding sequences and included 4046 coding sequences, some of which associated with stress response. The average nucleotide identity and digital DNA-DNA hybridization similarity between strain CAU 1483 ^T and related members of the genus Cohnella were 71.8-74.9% and 22.6-33.9%, respectively. The major respiratory quinone present in this strain was menaquinone-7. Strain CAU 1483 ^T contained anteiso-C_15:0 and iso-C_16:0 as the major fatty acids, while its polar lipids consisted of phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, lysyl-phosphatidylglycerol, phosphatidylcholine, three unidentified aminophospholipids, two unidentified lipids and an unidentified phospholipid. Peptidoglycan type was A1γ meso-Dpm. On the basis of taxonomic characterization, strain CAU 1483 ^T constitutes a novel species, for which the name Cohnella pontilimi sp. nov. is proposed. The type strain of this novel species is CAU 1483 ^T (= KCTC 43047 ^T = NBRC 113953 ^T).

Description of Cohnella zeiphila sp. nov., a bacterium isolated from maize callus cultures

A Gram-stain positive, aerobic, motile, rod-shaped bacterium designated as strain CBP-2801^T was isolated as a contaminant from a culture containing maize callus in Peoria, Illinois, United States. The strain is unique relative to other Cohnella species due to its slow growth and reduced number of sole carbon sources. Phylogenetic analysis using 16S rRNA indicated that strain CBP-2801^T is a Cohnella bacterium and showed the highest similarity to Cohnella xylanilytica (96.8%). Genome-based phylogeny and genomic comparisons based on average nucleotide identity confirmed the strain to be a novel species of Cohnella. Growth occurs at 15-45 °C (optimum 40 °C), pH 5-7 (optimum pH 6) and with 0-1% NaCl. The predominant fatty acids are anteiso-15:0 and 18:1 ω6c. Genome mining for secondary metabolites identified a putative biosynthetic cluster that encodes for a novel lasso peptide. In addition, this study contributes five new genome assemblies of type strains of Cohnella species, a genus with less than 30% of the type strains sequenced. The DNA G + C content is 58.7 mol %. Based on the phenotypic, phylogenetic and biochemical data strain CBP-2801^T represents a novel species, for which the name Cohnella zeiphila sp. nov. is proposed. The type strain is CBP-2801^T (= DSM 111598 = ATCC TSD-230).

Cohnella fermenti sp. nov., isolated from a fermentation process

A novel Gram-stain-positive, aerobic, motile with peritrichous flagella, rod-shaped bacterium, designated CC-MHH1044^T, was isolated from a preserved vegetable sample. A polyphasic taxonomic approach was applied to the isolates in order to clarify its taxonomic position. Growth of the strain CC-MHH1044^T occurred at 15-50 °C (optimum, 30 °C), pH 6.0-8.0 (optimum, pH 7.0) and with 0-2.0 % (w/v) NaCl (optimum, 1 %, w/v). The genome of strain CC-MHH1044^T consisted of 8.5 Mb and the genomic DNA G+C content was 58.5 mol%. Comparison of the 16S rRNA gene sequences showed that CC-MHH1044^T belonged to the genus Cohnella and showed a close relationship with the type strains of Cohnella damuensis (96.2 %) and Cohnella panacarvi (95.9 %), and lower sequence similarity to other species. Average nucleotide identity values calculated from whole-genome sequencing data proved that CC-MHH1044^T represents a distinct Cohnella species. The dominant cellular fatty acids (>5 %) included iso-C_14 : 0(7.4 %), iso-C_15 : 0 (6.4 %), anteiso-C_15 : 0(40.3 %), C_16 : 0 (6.6 %) and iso-C_16 : 0 (27.0 %). The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, four unidentified aminophospholipids, one unidentified phospholipid and glycolipid. The major polyamine was spermidine. The predominant isoprenoid quinone was menaqinone 7 (MK-7). Based on its distinct phylogenetic, phenotypic and chemotaxonomic traits, together with results of comparative 16S rRNA gene sequence, average nucleotide identity and digital DNA-DNA hybridization analyses, we conclude that strain CC-MHH1044^T represents a novel member of the genus Cohnella, for which the name Cohnella fermenti sp. nov. is proposed. The type strain is CC-MHH1044^T (=BCRC 81147^T=JCM 32834^T).

Cohnella endophytica sp. nov., a novel endophytic bacterium isolated from bark of Sonneratia apetala

A Gram-stain-positive, aerobic, rod-shaped, endospore-forming bacterium, designated strain M2MS4P-1^T, was isolated from surface-sterilized bark of Sonneratiaapetala sampled in Guangxi, China. The bacterium was characterized by a polyphasic approach to determine its taxonomic position. 16S rRNA gene sequence comparisons revealed that strain M2MS4P-1^T belonged to the genus Cohnella and was most closely to Cohnella luojiensis HY-22R^T (98.4 % similarity). The average nucleotide identity value and estimated DDH value between strain M2MS4P-1^T and the type strain of C. luojiensis HY-22R^T were 79.2 and 20.1 %, respectively. Neither substrate nor aerial mycelia were formed, and no diffusible pigments were observed on the media tested. Strain M2MS4P-1^T grew in the pH range 6.0-9.0 (optimum, pH 7.0-8.0), at temperatures between 10-37 °C (30 °C) and in 0-1 % (w/v) NaCl (0 %). The predominant isoprenoid quinone in strain M2MS4P-1^T was menaquinone-7. The major fatty acids were anteiso-C15 : 0 and iso-C16 : 0. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, lysyl-phosphatidylglycerol, four unidentified aminophospholipids and two unidentified phospholipids. The DNA G+C content was 51.5 mol%. According to the phylogenetic, phenotypic and chemotaxonomic evidence, strain M2MS4P-1^T was clearly distinguishable from other species with validly published names in the genus Cohnella and should therefore be classified as a novel species, for which we suggest the name Cohnellaendophytica sp. nov. The type strain is M2MS4P-1^T (=KCTC 43011^T=CGMCC 1.13745^T).

Cohnella faecalis sp. nov., isolated from animal faeces in a karst cave

A Gram-stain-positive, rod-shaped, endospore-forming, motile and aerobic bacterial isolate, designated strain K2E09-144^T, was obtained from animal faeces that were collected from a karst cave in Guizhou province, China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain K2E09-144^T represents a novel member of the genus Cohnella within the family Paenibacillaceae of the phylum Firmicutes. Strain K2E09-144^T was phylogenetically closely related to Cohnella nanjingensis D45^T (16S rRNA gene sequence similarity 97.0 %). The major cellular fatty acids were anteiso-C15:0, iso-C16:0 and C16 : 0. The major isoprenoid quinone was menaqinone 7 (MK-7). The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unidentified phospholipid, four unidentified aminophospholipids, one glycolipid and one unidentified lipid. The isomer type of diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The genome of strain K2E09-144^T comprised 6.43 Mb, and encoded 6029 genes in total. The DNA G+C content of the genomic DNA was 53.3 mol%. Based on its phylogenetic, phenotypic and chemotaxonomic characteristics, strain K2E09-144^T is considered to represent a novel species of the genus Cohnella, for which the name Cohnella faecalis sp. nov. is proposed. The type strain is K2E09-144^T (=CGMCC 1.13587^T=NBRC 113454^T).

Cohnella kolymensis sp. nov., a novel bacillus isolated from Siberian permafrost

A facultative anaerobic, rod-shaped, endospore-forming and non-motile bacterium was isolated from permafrost sediment cores in the Kolyma lowland, Siberia, Russia. The permafrost isolate clustered with members of the genus Cohnella on the basis of 16S rRNA gene sequence analysis and showed the highest sequence similarity to Cohnella saccharovorans CJ22^T (96.3 %), followed by Cohnella cellulosilytica FCN3-3^T (96.0 %) and Cohnella panacarvi KCTC 13060^T (96.0 %). The chemotaxonomic characteristics (quinone system, cellular fatty acids and polar lipid profile) of strain 20.16^T were consistent with members of the genus Cohnella. The peptidoglycan diaminoacids included meso-diaminopimelic acid and a small amount of ll-diaminopimelic acid. The molar ratio and composition of major amino acids (meso-diaminopimelic acid, alanine, and glutamic acid) correspond to the peptydoglycan type A1γ. The estimated genome size of strain 20.16^T is 4.34 Mb (lower than those in other Cohnella species). The genome has a G+C content of 50.5 mol% and encodes 4843 predicted genes, of these 4740 are protein-coding ones. The results of chemotaxonomic, physiological and biochemical characterization allowed clear differentiation of strain 20.16^T from the closest Cohnella species. Based on data provided, a new species Cohnella kolymensis sp. nov. is proposed, with 20.16^T (=VKM B-2846^T=DSM 104983^T) as the type strain.

Molecular evidence that cellulolytic bacterial genus Cohnella is widespread among Neotropical Nasutitermitinae from NE Argentina

Cohnella is a highly cellulolytic bacterial genus, which can be found in a variety of habitats. The aim of this study was to assess its presence in the digestive tract of termite species collected in North-eastern Argentina: Nasutitermes aquilinus, N. corniger and Cortaritermes fulviceps. Gut homogenates were incubated with cellulosic substrate for bacterial growth. Bacterial 16S rDNA was partially amplified using new primers for Cohnella spp. and cloned. Sequences obtained showed highest similarity (97.2-99.9%) with those of Cohnella spp. previously reported from diverse environments. Phylogenetic analysis tended to group the clones according to their host species and sampling sites. These results indicate the association of Cohnella-related intestinal symbionts with three common Neotropical termites. Their potential industrial application encourages further research.

Cohnella algarum sp. nov., isolated from a freshwater green alga Paulinella chromatophora

A Gram-stain-positive, facultatively aerobic and endospore-forming bacterium, designated strain Pch-40^T, was isolated from a freshwater green alga, Paulinella chromatophora. Cells were motile rods with a monotrichous polar flagellum showing catalase- and oxidase-positive reactions. Strain Pch-40^T grew at 20-50 °C (optimum, 37-40 °C), at pH 5.0-11.0 (optimum, pH 7.0) and in the presence of 0-4.0 % (w/v) NaCl (optimum, 0 %). Menaquinone-7 was detected as the sole isoprenoid quinone. The genomic DNA G+C content of strain Pch-40^T was 55.6 mol%. The major cellular fatty acids of strain Pch-40^T were C16 : 0, iso-C16 : 0, anteiso-C15 : 0 and anteiso-C17 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain Pch-40^T clearly belonged to the genus Cohnella of the family Paenibacillaceae. Strain Pch-40^T was most closely related to Cohnella rhizosphaerae CSE-5610^T with a 96.1 % 16S rRNA gene sequence similarity. The phenotypic and chemotaxonomic features and the phylogenetic inference clearly suggested that strain Pch-40^T represents a novel species of the genus Cohnella, for which the name Cohnellaalgarum sp. nov. is proposed. The type strain is strain Pch-40^T (=KACC 19279^T=JCM 32033^T).

Cohnella lubricantis sp. nov., isolated from a coolant lubricant solution

A Gram-stain-positive, aerobic, non-endospore-forming organism, isolated from a coolant lubricant solution was studied for its taxonomic position. On the basis of 16S rRNA gene sequence similarity comparisons, strain KSS-154-50T was grouped into the genus Cohnella, most closely related to Cohnella formosensisCC-ALFALFA-35T (97.3 % 16S rRNA gene sequence similarity), Cohnella rhizosphaerae CSE-5610T (97.1 %) and Cohnella nanjingensis D45T (97.0 %); the 16S rRNA gene sequence similarity to other species of the genus Cohnella was <97.0 %. The fatty acid profile from whole cell hydrolysates was very similar to those reported for other species of the genus Cohnella and supported the allocation to the genus Cohnella. In the fatty acid profiles, iso- and anteiso-branched fatty acids were found as major compounds. The quinone system consisted predominantly of menaquinone MK-7. The polar lipid profile contained the major lipids diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified phospholipid. The major polyamine is spermidine. The results of physiological and biochemical characterization allowed in addition a phenotypic differentiation of strain KSS-154-50T from the three most closely related species. Hence, strain KSS-154-50T represents a novel species of the genus Cohnella, for which the name Cohnella lubricantis sp. nov. is proposed. The type strain is KSS-154-50T (=LMG 29763T=CCM 8707T).

Cellulose-Enriched Microbial Communities from Leaf-Cutter Ant (Atta colombica) Refuse Dumps Vary in Taxonomic Composition and Degradation Ability

Deconstruction of the cellulose in plant cell walls is critical for carbon flow through ecosystems and for the production of sustainable cellulosic biofuels. Our understanding of cellulose deconstruction is largely limited to the study of microbes in isolation, but in nature, this process is driven by microbes within complex communities. In Neotropical forests, microbes in leaf-cutter ant refuse dumps are important for carbon turnover. These dumps consist of decaying plant material and a diverse bacterial community, as shown here by electron microscopy. To study the portion of the community capable of cellulose degradation, we performed enrichments on cellulose using material from five Atta colombica refuse dumps. The ability of enriched communities to degrade cellulose varied significantly across refuse dumps. 16S rRNA gene amplicon sequencing of enriched samples identified that the community structure correlated with refuse dump and with degradation ability. Overall, samples were dominated by Bacteroidetes, Gammaproteobacteria, and Betaproteobacteria. Half of abundant operational taxonomic units (OTUs) across samples were classified within genera containing known cellulose degraders, including Acidovorax, the most abundant OTU detected across samples, which was positively correlated with cellulolytic ability. A representative Acidovorax strain was isolated, but did not grow on cellulose alone. Phenotypic and compositional analyses of enrichment cultures, such as those presented here, help link community composition with cellulolytic ability and provide insight into the complexity of community-based cellulose degradation.

Cohnella saccharovorans sp. nov., isolated from ginseng soil

A novel bacterial strain, CJ22T, was isolated from soil of a ginseng field located in Anseong, Korea. Cells of strain CJ22T were aerobic, Gram-stain-positive, endospore-forming, motile, oxidase- and catalase-positive and rod-shaped. The isolate grew optimally at pH 7 and 30 °C. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain CJ22T belonged to the genus Cohnella, displaying highest sequence similarity of 97.3% with Cohnella panacarvi Gsoil 349T. DNA-DNA relatedness between strain CJ22T and its closest relative was 35.5 % (reciprocal value, 23.8%). The phenotypic features of strain CJ22T also distinguished it from related species of the genus Cohnella. The diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The major isoprenoid quinone was menaquinone MK-7 and the major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, lysyl-phosphatidylglycerol, two unidentified phospholipids and two unidentified aminophospholipids. The predominant cellular fatty acids of strain CJ22T were anteiso-C15 : 0, iso-C16:0 and C16:0. The DNA G+C content was 63.1 mol%. Based on data from this polyphasic taxonomic study, strain CJ22T is considered to represent a novel species of the genus Cohnella, for which the name Cohnella saccharovorans sp. nov. is proposed. The type strain is CJ22T (=KACC 17501T=JCM 19227T).

Cohnella collisoli sp. nov., isolated from lava forest soil

A novel bacterial strain, NKM-5T, was isolated from soil of a lava forest in Nokkome Oreum, Jeju, Republic of Korea. Cells of strain NKM-5T were Gram-stain-positive, motile, endospore-forming, rod-shaped and oxidase- and catalase-positive. Strain NKM-5T contained anteiso-C15 : 0 and iso-C16 : 0 as the major fatty acids; menaquinone-7 (MK-7) as the predominant isoprenoid quinone; diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, lysyl-phosphatidylglycerol, an unidentified phospholipid and three unidentified aminophospholipids as the polar lipids; and meso-diaminopimelic acid as the diagnostic diamino acid in the cell-wall peptidoglycan. The DNA G+C content was 48.3 mol%. Phylogenetic analysis, based on 16S rRNA gene sequencing, showed that strain NKM-5T was most closely related to Cohnella lupini RLAHU4BT (96.9 % sequence similarity) and fell into a clade in the genus Cohnella. On the basis of phylogenetic, chemotaxonomic and phenotypic data, strain NKM-5T represents a novel species of the genus Cohnella, for which the name Cohnella collisoli sp. nov. is proposed. The type strain is NKM-5T ( = KCTC 33634T = CECT 8805T).

Ammoniibacillus agariperforans gen. nov., sp. nov., a thermophilic, agar-degrading bacterium isolated from compost

A thermophilic, agar-degrading bacterium, strain FAB2(T), was isolated from sewage sludge compost. According to phylogenetic analysis based on 16S rRNA gene sequences, strain FAB2(T) belonged to the family Paenibacillaceae within the phylum Firmicutes. However, FAB2(T) was different enough at the genus level from closely related species. The percentages of 16S rRNA gene sequence similarity with related organisms were 90.4 % for Thermobacillus xylanilyticus, 91.8 % for Paenibacillus barengoltzii, 89.4 % for Cohnella lupini, 90.1 % for Fontibacillus aquaticus, and 89.0 % for Saccharibacillus sacchari. Morphological and physiological analyses revealed that the strain was motile, rod-shaped, Gram-stain-positive, aerobic and able to form oval endospores in swollen sporangia. Ammonium was required as a nitrogen source while nitrate, nitrite, urea and glutamate were not utilized. Catalase and oxidase activities were weakly positive and positive, respectively. The bacterium grew in the temperature range of 50-65 °C and in media with pH 7.5 to 9.0. Optimal growth occurred at 60 °C and pH 8.0-8.6. Growth was inhibited at pH≤7.0 and NaCl concentrations ≥2.5 % (w/v). In chemotaxonomic characterization, MK-7 was identified as the dominant menaquinone. Major fatty acids were iso-C16 : 0 and C16 : 0. Dominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Phosphatidylcholine was present in a moderate amount. The diamino acid in the cell wall was meso-diaminopimelic acid. The G+C content of the genomic DNA was 49.5 mol% in a nucleic acid study. On the basis of genetic and phenotypic characteristics, strain FAB2(T) ( = NBRC 109510(T) = KCTC 33130(T)) showed characteristics suitable for classification as the type strain of a novel species of a new genus in the family Paenibacillaceae, for which the name Ammoniibacillus agariperforans gen. nov., sp. nov. is proposed.

Cohnella nanjingensis sp. nov., an extracellular polysaccharide-producing bacterium isolated from soil

A Gram-stain-positive, rod-shaped, endospore-forming bacterium, strain D45T, was isolated from soil in Nanjing, China. The organism grew optimally at 30 °C, pH 7.0 and with 0 % NaCl (w/v). The 16S rRNA gene sequence of the isolate showed similarities lower than 97 % with respect to species of the genus Cohnella . The predominant respiratory quinone was MK-7, with MK-6 present as a minor component; anteiso-C15 : 0 and iso-C16 : 0 were the major fatty acids. The polar lipids of strain D45T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two aminophospholipids, four phospholipids, two glycolipids, one aminolipid and two lipids. The DNA G+C content was 59.5 mol%. DNA–DNA hybridization of the isolate with two reference strains showed relatedness values of 33.4 % with Cohnella ginsengisoli DSM 18997T and 25.8 % with Cohnella thermotolerans DSM 17683T. The phylogenetic, chemotaxonomic and phenotypic data supported the classification of strain D45T as a representative of a novel species of the genus Cohnella , for which the name Cohnella nanjingensis sp. nov. is proposed. The type strain is D45T ( = CCTCC AB 2014067T = DSM 28246T).

Cohnella rhizosphaerae sp. nov., isolated from the rhizosphere environment of Zea mays

A Gram-staining-positive, aerobic, non-endospore forming organism, isolated as a seed endophyte (colonizing the internal healthy tissue of plant seed) of sweet corn (Zea mays), strain CSE-5610T, was studied for its taxonomic allocation. On the basis of 16S rRNA gene sequence comparisons, strain CSE-5610T was grouped into the genus Cohnella, most closely related to Cohnella ginsengisoli GR21-5T (98.1%) and 'Cohnella plantaginis' YN-83 (97.5%). The 16S rRNA gene sequence similarity to other members of the genus Cohnella was <96.6%. DNA-DNA hybridization of strain CSE-5610T with C. ginsengisoli DSM 18997T and 'C. plantaginis' DSM 25424 was 58% (reciprocal 24%) and 30% (reciprocal 27%), respectively. The fatty acid profile from whole cell hydrolysates supported the allocation of the strain to the genus Cohnella; iso- and anteiso-branched fatty acids were found as major compounds. meso-Diaminopimelic acid was identified as the cell-wall diamino acid. The quinone system consisted predominantly of menaquinone MK-7. The polar lipid profile was composed of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two aminophospholipids, a phospholipid and minor amounts of two polar lipids. In the polyamine pattern, spermidine was the major polyamine. The G+C content of the genomic DNA was 60 mol%. In addition, the results of physiological and biochemical tests also allowed phenotypic differentiation of strain CSE-5610T from the two closely related strains. Hence, CSE-5610T represents a novel species of the genus Cohnella, for which we propose the name Cohnella rhizosphaerae sp. nov., with CSE-5610T (=LMG 28080T=CIP 110695T) as the type strain.

Cohnella lupini sp. nov., an endophytic bacterium isolated from root nodules of Lupinus albus

A bacterial strain designated RLAHU4BT was isolated from root nodules of Lupinus albus in León (Spain). The 16S rRNA gene sequence of this strain showed similarities lower than 97 % with respect to species of the genus Cohnella . The strain was a Gram-variable, sporulating rod, motile by means of peritrichous flagella, and facultatively anaerobic. It was positive for oxidase, catalase and β-galactosidase production but negative for urease, amylase and gelatinase. Strain RLAHU4BT grew in the presence of 5 % NaCl. MK-7 was the predominant menaquinone and meso-diaminopimelic acid was present in the peptidoglycan. anteiso-C15 : 0, iso-C16 : 0, iso-C15 : 0 and C16 : 0 were the major fatty acids. Major polar lipids of strain RLAHU4BT were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unknown phospholipids, two unknown aminophospholipids and one unknown lipid. The DNA G+C content was 57.8 mol%. Strain RLAHU4BT presented phenotypic differences from all recognized species of the genus Cohnella . The phylogenetic, chemotaxonomic and phenotypic data indicated that strain RLAHU4BT belongs to a novel species of the genus Cohnella , for which the name Cohnella lupini sp. nov. is proposed, with strain RLAHU4BT ( = LMG 27416T = CECT 8236T) as the type strain.

Cohnella formosensis sp. nov., a xylanolytic bacterium isolated from the rhizosphere of Medicago sativa L

A Gram-positive, spore-forming, aerobic, rod-shaped, xylanolytic bacterium designated strain CC-Alfalfa-35(T) was isolated from the rhizosphere of Medicago sativa L. in Taiwan. Phylogenetic analysis based on 16S rRNA gene sequence showed that strain CC-Alfalfa-35(T) was affiliated to the genus Cohnella. Strain CC-Alfalfa-35(T) shared 95.3 % pairwise 16S rRNA gene sequence similarity to the type strain of the type species of the genus Cohnella (Cohnella thermotolerans DSM 17683(T)) besides showing a similarity of 97.4-93.6 % with other recognized species of the genus Cohnella. The DNA-DNA hybridization value between CC-Alfalfa-35(T) and Cohnella thailandensis KCTC 22296(T) was 37.7 % ± 1.7 % (reciprocal value, 55.7 % ± 3.0 %). Predominant cellular fatty acids were iso-C16 : 0 and anteiso-C15 : 0. The polar lipid profile constituted diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, lysyl-phosphatidylglycerol, three unidentified phospholipids and three unidentified aminophospholipids. The major respiratory quinone was MK-7 and the DNA G+C content was 58.3 mol%. Strain CC-Alfalfa-35(T) contained meso-diaminopimelic acid as the major diamino acid in the cell-wall peptidoglycan. Based on the polar lipid and fatty acid profiles, which were in line with those of C. thermotolerans DSM 17683(T), coupled with additional distinguishing genotypic, phenotypic and chemotaxonomic features, strain CC-Alfalfa-35(T) is proposed to represent a novel species within the genus Cohnella, for which the name Cohnella formosensis sp. nov. is proposed. The type strain is CC-Alfalfa-35(T) ( = JCM 18405(T) = BCRC 80428(T)).