Gracilibacillus quinghaiensis sp. nov., isolated from salt-lake sediment in the Qaidam Basin, north-west China

Gracilibacillus pellucidus sp. nov., a moderately halophilic bacterium isolated from saline soil in Xinjiang province, China

A motile, Gram-positive, moderately halophilic, catalase-positive and oxidase-negative, obligate aerobic, slender rod-shaped bacterium, strain S3-1-1T was isolated from the plant rhizosphere soil in saline soil of Xinjiang Uygur Autonomous Region. Strain S3-1-1T grew in the presence of 1-21% NaCl and at pH 7.0-9.0, with optimum growth at 3% NaCl and pH 7.5. It grew at 16-45 °C, with optimum growth at 40 °C.Phylogenetic analysis based on 16S rRNA gene sequences showed that strain S3-1-1T should be placed within the genus Gracilibacillus and formed a separate branch. It exhibited highest similarities to Gracilibacillus ureilyticus MF38T (sequence similarity 97.7%), Gracilibacillus massiliensis Awa-1T (sequence similarity 97.5%), Gracilibacillus xinjiangensis J2T (sequence similarity 97.4%) and Gracilibacillus salitolerans SCU50T (sequence similarity 97.4%). Genomic comparisons revealed that strain S3-1-1T shares closest phylogenetic relationships with Gracilibacillus saliphilus YIM 91119T (ANI 77.4%, AAI 78.4%), Gracilibacillus thailandensis TP2-8T (ANI 77.2%, AAI 78.3%), and Gracilibacillus salitolerans SCU50T (ANI 77.3%, AAI 78.1%). However, the digital DNA-DNA hybridization (19.3-22.1%), average nucleotide identity (71.1-77.4%), and average amino acid identity (66.9-78.6%) values all fell below the recommended thresholds for species delineation, supporting its novel taxonomic status. The major cellular fatty acids were anteiso-C15:0, C16:0, iso-C15:0, and anteiso-C17:0. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and aminophospholipids. On the basis of their phenotypic, physiological, biochemical and phylogenetic characteristics, S3-1-1T represented a novel species of the genus Gracilibacillus, for which the name Gracilibacillus pellucidus sp. nov. is proposed, with S3-1-1T (= JCM 36422T = GDMCC 1.4017T) as the type strain.

Gracilibacillus suaedae sp. nov., an indole acetic acid-producing endophyte isolated from a root of Suaeda salsa

A Gram-stain-positive, facultatively anaerobic, spore-forming, motile with unipolar biflagella, rod-shaped, indole acetic acid-producing bacterium, named LD4P30^T, was isolated from a root of Suaeda salsa collected in Inner Mongolia, northern China. Strain LD4P30^T grew at pH 6.0-11.0 (optimum, pH 7.0), 10-40 °C (35 °C) and in the presence of 1-15% (w/v) NaCl (5%). The strain was positive for oxidase and negative for catalase. The major cellular fatty acids of strain LD4P30^T were iso-C_15:0, C_15:1 ω5c and anteiso-C_15:0; the major polar lipids were diphosphatidylglycerol and phosphatidylglycerol; and menaquinone-7 was the only respiratory quinone. The genomic DNA G+C content was 36.7 mol%. A phylogenetic tree based on 16S rRNA gene sequences showed that strain LD4P30^T clustered with Gracilibacillus thailandensis TP2-8^T, Gracilibacillus saliphilus YIM 91119^T and Gracilibacillus lacisalsi BH312^T, and showed 99.0, 98.9, 98.0 and <97.7% 16S rRNA gene similarity to G. thailandensis TP2-8^T, G. saliphilus YIM 91119^T, G. lacisalsi BH312^T and all other current type strains, respectively. The digital DNA-DNA hybridization and average nucleotide identity based on blast values between strain LD4P30^T and G. saliphilus YIM 91119^T, G. thailandensis TP2-8^T and G. lacisalsi BH312^T were 44.9, 44.7 and 44.4%, and 91.1, 91.0 and 90.8%, respectively. Based on its phenotypic, physiological and phylogenetic characteristics, strain LD4P30^T represents a novel species, for which the name Gracilibacillus suaedae is proposed. The type strain is LD4P30^T (=CGMCC 1.17697^T=KCTC 82375^T).

Characterization of β-galactosidase and α-galactosidase activities from the halophilic bacterium Gracilibacillus dipsosauri

Purpose

Gracilibacillus dipsosauri strain DD1 is a salt-tolerant Gram-positive bacterium that can hydrolyze the synthetic substrates o-nitrophenyl-β-d-galactopyranoside (β-ONP-galactose) and p-nitrophenyl-α-d-galactopyranoside (α-PNP-galactose). The goals of this project were to characterize the enzymes responsible for these activities and to identify the genes encoding them.

Methods

G. dipsosauri strain DD1 was grown in tryptic soy broth containing various carbohydrates at 37 °C with aeration. Enzyme activities in cell extracts and whole cells were measured colorimetrically by hydrolysis of synthetic substrates containing nitrophenyl moieties. Two enzymes with β-galactosidase activity and one with α-galactosidase activity were partially purified by ammonium sulfate fractionation, ion-exchange chromatography, and gel-filtration chromatography from G. dipsosauri. Coomassie Blue-stained bands corresponding to each activity were excised from nondenaturing polyacrylamide gels and subjected to peptide sequencing after trypsin digestion and HPLC/MS analysis.

Result

Formation of β-galactosidase and α-galactosidase activities was repressed by d-glucose and not induced by lactose or d-melibiose. β-Galactosidase I had hydrolytic and transgalactosylation activity with lactose as the substrate but β-galactosidase II showed no activity towards lactose. The α-galactosidase had hydrolytic and transgalactosylation activity with d-melibiose but not with d-raffinose. β-Galactosidase I had a lower Km with β-ONP-galactose as the substrate (0.693 mmol l−1) than β-galactosidase II (1.662 mmol l−1), was active at more alkaline pH, and was inhibited by the product d-galactose. β-Galactosidase II was active at more acidic pH, was partially inhibited by ammonium salts, and showed higher activity with α-PNP-arabinose as a substrate. The α-galactosidase had a low Km with α-PNP-galactose as the substrate (0.338 mmol l−1), a pH optimum of about 7, and was inhibited by chloride-containing salts. β-Galactosidase I activity was found to be due to the protein A0A317L6F0 (encoded by gene DLJ74_04930), β-galactosidase II activity to the protein A0A317KZG3 (encoded by gene DLJ74_12640), and the α-galactosidase activity to the protein A0A317KU47 (encoded by gene DLJ74_17745).

Conclusions

G. dipsosauri forms three intracellular enzymes with different physiological properties which are responsible for the hydrolysis of β-ONP-galactose and α-PNP-galactose. BLAST analysis indicated that similar β-galactosidases may be formed by G. ureilyticus, G. orientalis, and G. kekensis and similar α-galactosidases by these bacteria and G. halophilus.

Isolation of a novel halothermophilic strain of the genus Gracilibacillus from Howz-e Sultan hypersaline lake in Iran

Background and Objectives:

Halothermophilic bacteria are adapted to high osmolarity and can grow in high saline environments and high temperatures. This study was aimed at the isolation of halothermophilic bacteria from Howz-e Sultan hypersaline lake in the central desert zone in Iran.

Materials and Methods:

Samples were collected and after preparing dilutions, the samples were cultured on Molten haloid agar with different salt concentrations (5–35%), then the plates were incubated at 35–70ºC in both aerobic and anaerobic conditions. Biochemical characterizations, utilization of carbon sources, production of exoenzymes and antibiotic susceptibility were investigated. Taxonomic and phylogenetic analyses were performed using 16S rRNA gene sequences.

Results:

One of the isolated bacteria was found to be Gram-positive, hyperhalophilic, thermophilic, endospore-forming, and was named as 1–9 h isolate. The bacterial cells were bacilli-shaped, which produced endospores at a subterminal position. This isolate was an aerobe and facultative anaerobe and grew between pH 5.0 and 10.0 (optimal growth at pH 7.0–7.5), at temperature between 15°C and 65°C (optimal growth at 40–45°C) and at salinity of 9–32% (w/v) NaCl, growing optimally at 18% (w/v) NaCl. On the basis of 16S rRNA gene sequence analysis, isolate 1–9 h belongs to the genus Bacillus within the phylum Firmicutes and showed the closest phylogenetic similarity to Gracilibacillus sp. IBP-V003 (99.0%).

Conclusion:

Based on the results of its phenotypic and genotypic properties, strain 1–9 h represents a novel strain of the genus Gracilibacillus. It can be used in various fields of industry and biotechnology.

From ecophysiology to cultivation methodology: filling the knowledge gap between uncultured and cultured microbes

Earth is dominated by a myriad of microbial communities, but the majority fails to grow under in situ laboratory conditions. The basic cause of unculturability is that bacteria dominantly occur as biofilms in natural environments. Earlier improvements in the culture techniques are mostly done by optimizing media components. However, with technological advancement particularly in the field of genome sequencing and cell imagining techniques, new tools have become available to understand the ecophysiology of microbial communities. Hence, it becomes easier to mimic environmental conditions in the culture plate. Other methods include co-culturing, emendation of growth factors, and cultivation after physical cell sorting. Most recently, techniques have been proposed for bacterial cultivation by employing genomic data to understand either microbial interactions (network-directed targeted bacterial isolation) or ecosystem engineering (reverse genomics). Hopefully, these techniques may be applied to almost all environmental samples, and help fill the gaps between the cultured and uncultured microbial communities.

Gracilibacillus kimchii sp. nov., a halophilic bacterium isolated from kimchi

A novel halophilic bacterium, strain K7(T), was isolated from kimchi, a traditional Korean fermented food. The strain is Gram-positive, motile, and produces terminal endospores. The isolate is facultative aerobic and grows at salinities of 0.0-25.0% (w/v) NaCl (optimum 10-15% NaCl), pH 5.5-8.5 (optimum pH 7.0-7.5), and 15-42°C (optimum 37°C). The predominant isoprenoid quinone in the strain is menaquinone-7 and the peptidoglycan of the strain is meso-diaminopimelic acid. The major fatty acids of the strain are anteisio-C15:0, iso-C15:0, and, C16:0 (other components were < 10.0%), while the major polar lipids are diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, and three unidentified lipids. A phylogenetic analysis of 16S rRNA gene sequence similarity showed that the isolated strain was a cluster of the genus Gracilibacillus. High levels of gene sequence similarity were observed between strain K7(T) and Gracilibacillus orientalis XH-63(T) (96.5%), and between the present strain and Gracilibacillus xinjiangensis (96.5%). The DNA G+C content of this strain is 37.7 mol%. Based on these findings, strain K7(T) is proposed as a novel species: Gracilibacillus kimchii sp. nov. The type strain is K7(T) (KACC 18669(T); JCM 31344(T)).

Gracilibacillus alcaliphilus sp. nov., a facultative alkaliphile isolated from indigo fermentation liquor for dyeing

A facultatively alkaliphilic, lactic-acid-producing and halophilic strain, designated SG103T, was isolated from a fermented Polygonum indigo (Polygonum tinctorium Lour.) liquor sample for dyeing prepared in a laboratory. 16S rRNA gene sequence phylogeny suggested that SG103T is a member of the genus Gracilibacillus with the closest relatives being ‘Gracilibacillus xinjiangensis’ J2 (similarity: 97.06 %), Gracilibacillus thailandensis TP2-8T (97.06 %) and Gracilibacillus halotolerans NNT (96.87 %). Cells of the isolate stained Gram-positive and were facultatively anaerobic straight rods that were motile by peritrichous flagella. The strain grew at temperatures between 13 and 48 °C with the optimum at 39 °C. It grew in the range pH 7–10 with the optimum at pH 9. The isoprenoid quinone detected was menaquinone-7 (MK-7) and the DNA G+C content was 41.3 mol%. The whole-cell fatty acid profile mainly (>10 %) consisted of iso-C15 : 0, anteiso-C15 : 0 and anteiso-C17 : 0. Unlike other reported species of the genus Gracilibacillus , the strain lacked diphosphatidylglycerol as a major polar lipid. DNA–DNA hybridization experiments with strains exhibiting greater than 96.87 % 16S rRNA gene sequence similarity, ‘G. xinjiangensis’ J2, G. thailandensis TP2-8T and G. halotolerans NNT, revealed 2±4 %, 4±9 % and 3±2 % relatedness, respectively. On the basis of the differences in phenotypic and chemotaxonomic characteristics, and the results of phylogenetic analyses based on 16S rRNA gene sequences and DNA–DNA relatedness data from reported species of the genus Gracilibacillus , strain SG103T merits classification as a members of a novel species, for which the name Gracilibacillus alcaliphilus sp. nov. is proposed. The type strain is SG103T ( = JCM 17253T = NCIMB 14683T).

Gracilibacillus xinjiangensis sp. nov., a new member of the genus Gracilibacillus isolated from Xinjiang region, China

A Gram-positive, endospore-forming, rod-shaped bacterium, designated isolate J2(T) was isolated from a soil sample from Xinjiang Uyghur Autonomous Region, China. The isolate was observed to grow at 16-46 °C and pH 6.5-8.0. Chemotaxonomic analysis showed menaquinone-7 (MK-7) to be the major isoprenoid quinone; diphosphatidylglycerol, phosphatidylglycerol, one aminophospholipid, two phosphoglycolipids and one glycolipid as the major cellular polar lipids; and anteiso-C15:0, iso-C15:0, anteiso-C17:0 and C16:0 as the major fatty acids. Comparative analyses of the 16S rRNA gene sequence showed that strain J2(T) is most closely related to Gracilibacillus ureilyticus (with 98.8 % similarity), Gracilibacillus dipsosauri (97.2 %), Gracilibacillus quinghaiensis (97.1 %) and Gracilibacillus thailandensis (97.0 %). The DNA-DNA reassociation values between strain J2(T) and G. ureilyticus MF38(T), G. dipsosauri DD1(T), G. quinghaiensis YIM-C229(T) and G. thailandensis TP2-8(T) were 29.8 ± 3.7, 23.0 ± 3.5, 15.8 ± 4.9 and 15.9 ± 5.0 %, respectively. The genomic DNA G+C content of strain J2(T) was determined to be 36.5 mol%. Based on these data, strain J2(T) is considered as a novel species of the genus Gracilibacillus, for which the name Gracilibacillus xinjiangensis sp. nov. is proposed. The type species is J2(T) (= CGMCC 1.12449(T) = JCM 18859(T)).

Gracilibacillus bigeumensis sp. nov., a moderately halophilic bacterium from solar saltern soil

A Gram-staining-positive, moderately halophilic bacterium, designated strain BH097T, was isolated from solar saltern soil of Bigeum Island in south-west Korea. Cells were motile rods, producing spherical endospores at a terminal position in swollen sporangia. Strain BH097T was strictly aerobic, grew at pH 5.5–9.5 (optimum, pH 8.0), at 10–52 °C (optimum, 37 °C) and at salinities of 1–22 % (w/v) NaCl (optimum, 7 % NaCl). On the basis of 16S rRNA gene sequence analysis, strain BH097T was shown to belong to the genus Gracilibacillus within the phylum Firmicutes , and showed closest sequence similarity to Gracilibacillus saliphilus DSM 19802T (95.8 %), Gracilibacillus thailandensis TP2-8T (95.6 %), Gracilibacillus boraciitolerans DSM 17256T (95.5 %), ‘Gracilibacillus quinghaiensis’ DSM 17858 (95.4 %) and Gracilibacillus halophilus DSM 17856T (95.2 %). The DNA G+C content of this novel isolate was 37.9 mol%. The major cellular fatty acids of strain BH097T were anteiso-C15 : 0, iso-C15 : 0 and C16 : 0, and its polar lipid pattern consisted of diphosphatidylglycerol, phosphatidylglycerol two unknown phospholipids and a glycolipid. The isoprenoid quinone was MK-7, and the peptidoglycan type was A1γ, with meso-diaminopimelic acid as the diagnostic diamino acid. On the basis of polyphasic evidence from this study, strain BH097T represents a novel species of the genus Gracilibacillus for which the name Gracilibacillus bigeumensis sp. nov. is proposed. The type strain is BH097T ( = KCTC 13130T = DSM 19028T).

Gracilibacillus kekensis sp. nov., a moderate halophile isolated from Keke Salt Lake

A novel moderately halophilic bacterium, designated strain K170(T), was isolated from Keke Salt Lake in Qinghai, China. The strain grew with 0-22 % (w/v) NaCl, at 4-50 °C and at pH 6-11, with optimum growth in 3 % (w/v) NaCl, at 40 °C and at pH 8. The predominant respiratory quinone was menaquinone 7 (MK-7). The polar lipids included diphosphatidylglycerol, phosphatidylglycerol, unidentified phospholipids, aminolipids and glycolipids. The major cellular fatty acids were anteiso-C(15 : 0), iso-C(15 : 0) and anteiso-C(17 : 0). The DNA G+C content was 35.8 mol%. Phylogenetic analysis based on the full-length 16S rRNA gene sequence revealed that strain K170(T) was a member of the genus Gracilibacillus. High levels of 16S rRNA gene sequence similarity were found between strain K170(T) and Gracilibacillus boraciitolerans DSM 17256(T) (97.3 %) and Gracilibacillus thailandensis JCM 15569(T) (97.1 %). 16S rRNA gene sequence similarities between strain K170(T) and the type strains of other recognized members of the genus Gracilibacillus were below 97 %. The DNA-DNA hybridization values of strain K170(T) with G. boraciitolerans DSM 17256(T) and G. thailandensis JCM 15569(T) were 21.9 % and 34.3 %, respectively. On the basis of these results, strain K170(T) is considered to represent a novel species of the genus Gracilibacillus, for which the name Gracilibacillus kekensis sp. nov. is proposed; the type strain is K170(T) ( = CGMCC 1.10681(T) = DSM 23178(T)).

Gracilibacillus ureilyticus sp. nov., a halotolerant bacterium from a saline–alkaline soil

A Gram-stain-positive, halotolerant, neutrophilic, rod-shaped bacterium, strain MF38T, was isolated from a saline–alkaline soil in China and subjected to a polyphasic taxonomic characterization. The isolate grew in the presence of 0–15 % (w/v) NaCl and at pH 6.5–8.5; optimum growth was observed with 3.0 % (w/v) NaCl and at pH 7.0. Chemotaxonomic analysis showed menaquinone MK-7 as the predominant respiratory quinone and anteiso-C15 : 0, anteiso-C17 : 0, iso-C15 : 0, C17 : 0 and C16 : 0 as major fatty acids. The genomic DNA G+C content was 35.3 mol%. 16S rRNA gene sequence similarities of strain MF38T with type strains of described Gracilibacillus species ranged from 95.3 to 97.7 %. Strain MF38T exhibited the closest phylogenetic affinity to the type strain of Gracilibacillus dipsosauri, with 97.7 % 16S rRNA gene sequence similarity. The DNA–DNA reassociation between strain MF38T and G. dipsosauri DSM 11125T was 45 %. On the basis of phenotypic and genotypic data, strain MF38T represents a novel species of the genus Gracilibacillus, for which the name Gracilibacillus ureilyticus sp. nov. (type strain MF38T =CGMCC 1.7727T =JCM 15711T) is proposed.

Gracilibacillus thailandensis sp. nov., from fermented fish (pla-ra)

A novel strain, designated TP2-8(T), was isolated from fermented fish (pla-ra) in Thailand. It stained Gram-positive and the cells were aerobic, endospore-forming rods. The strain grew at pH 6-8 (optimum pH 7), 15-55 degrees C (optimum 37 degrees C) and 1-22 % (w/v) NaCl (optimum 5-10 %). It contained meso-diaminopimelic in the cell-wall peptidoglycan. MK-7 and cellular fatty acids anteiso-C(15 : 0), iso-C(15 : 0) and anteiso-C(17 : 0) were major components. Polar lipids diphosphatidylglycerol and phosphatidylglycerol and unidentified lipids were detected. The DNA G+C content was 37.6 mol%. Comparison of the 16S rRNA gene sequence of strain TP2-8(T) with those of other members of the family Bacillaceae indicated that it was a member of the genus Gracilibacillus (94.9-99.2 % sequence similarity) and was closely related to Gracilibacillus saliphilus YIM 91119(T) (99.2 % similarity), G. lacisalsi BH312(T) (98.6 %), G. orientalis XH-63(T) (97.7 %), 'G. quinghaiensis' YIM C229 (97.7 %) and G. boraciitolerans T-16X(T) (97.2 %). Strain TP2-8(T) showed low DNA-DNA relatedness (< or = 49%) to G. saliphilus YIM 91119(T), G. lacisalsi DSM 19029(T), G. orientalis CCM 7326(T), 'G. quinghaiensis' DSM 17858 and G. boraciitolerans JCM 21714(T). On the basis of the physiological and biochemical characteristics and molecular data presented, strain TP2-8(T) is proposed to represent a novel species, Gracilibacillus thailandensis sp. nov. (type strain TP2-8(T) =JCM 15569(T) =PCU 304(T) =TISTR 1881(T)).