Genomic insights into the salt tolerance and cold adaptation of Planococcus halotolerans SCU63T

Planococcus halotolerans, recently described as a novel species with SCU63^T as the type strain, is capable of thriving in up to 15% NaCl and temperatures as low as 0 °C. To better understand its adaptation strategies at the genomic level, strain SCU63^T was subjected to whole-genome sequencing and data mining. The high-quality assembly yielded 17 scaffolds with a genome size of 3,622,698 bp. Its genome harbors 3683 protein-coding sequences and 127 RNA genes, as well as three biosynthetic gene clusters and 25 genomic islands. The phylogenomic tree provided compelling insights into the evolutionary relationships of Planococcus. Comparative genomic analysis revealed key similarities and differences in the functional gene categories among Planococcus species. Strain SCU63^T was shown to have diverse stress response systems for high salt and cold habitats. Further comparison with three related species showed the presence of numerous unique gene clusters in the SCU63^T genome. The strain might serve as a good model for using extremozymes in various biotechnological processes.

Gracilibacillus salitolerans sp. nov., a moderate halophile isolated from saline soil in Northwest China

A moderately halophilic strain, designated SCU50T, was recovered from a saline soil sample and characterized by a polyphasic approach. The 16S rRNA gene sequence analysis showed that strain SCU50T belonged to the genus Gracilibacillus and was most closely related to Gracilibacillus thailandensis TP2-8T (98.1 % similarity) and Gracilibacillus orientalis XH-63T (97.7 %). Genomic average nucleotide identity and digital DNA–DNA hybridization analyses confirmed the separate species status of the new isolate relative to other recognized Gracilibacillus species. The genome size was about 5.09 Mbp and the DNA G+C content was 36.7 mol%. The strain grew optimally at 10–15 % (w/v) NaCl, pH 6.5–7.5 and 25–30 °C. It contained anteiso-C15 : 0, iso-C15 : 0 and anteiso-C17 : 0 as the dominant fatty acids and menaquinone-7 as the major respiratory quinone. The polar lipid profile was examined and found to comprise diphosphatidylglycerol, phosphatidylglycerol, one unidentified phospholipid and one unidentified lipid. The cell-wall peptidoglycan type was A1γ based on meso-diaminopimelic acid. Combining the data from phenotypic, chemotaxonomic, genomic and phylogenetic characterization, it was concluded that strain SCU50T should be assigned as representing a novel species within the genus Gracilibacillus . Thus, a novel taxon named Gracilibacillus salitolerans sp. nov. was first established, with SCU50T (=CGMCC 1.17336T=KCTC 43107T) as the type strain.

Characteristics of Planococcus antioxidans sp. nov., an antioxidant-producing strain isolated from the desert soil in the Qinghai-Tibetan Plateau

Strain Y74^T was an isolate from the sandy soil in the town of Huatugou, Qinghai-Tibet Plateau, China. An analysis of this strain's phenotypic, chemotaxonomic, and genomic characteristics established the relationship of the isolate with the genus Planococcus. Strain Y74^T was able to grow between 4 and 42°C (with an optimum temperature of 28°C) at pH values of 6-8.5 and in 0%-7% (w/v) NaCl. The dominant quinones were MK-8 and MK-7. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, and an unknown phospholipid. The majority of the fatty acid content was anteiso-C_15:0 (28.8%) followed by C_16:1 ω7c alcohol (20.9%) and iso-C_14:0 (13.4%). The 16S rRNA gene sequence similarity analysis demonstrated a stable branch formed by strain Y74^T and Planococcus halotolerans SCU63^T (99.66%). The digital DNA-DNA hybridization between these two strains was 57.2%. The G + C content in the DNA of Y74^T was 44.5 mol%. In addition, the morphological, physiological, and chemotaxonomic pattern clearly differentiated the isolates from their known relatives. In conclusion, the strain Y74^T (=JCM 32826^T  = CICC24461^T ) represents a novel member of the genus Planococcus, for which the name Planococcus antioxidans sp. nov. is proposed. Strain Y74^T was found to have potent antioxidant activity via its hydrogen peroxide tolerance and its 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity. The DPPH radical-scavenging activity was determined to be 40.2 ± 0.7%. The genomic analysis indicated that six peroxidases genes, one superoxide dismutase gene, and one dprA (DNA-protecting protein) are present in the genome of Y74^T .

Planococcus lenghuensis sp. nov., an oil-degrading bacterium isolated from petroleum-contaminated soil

A Gram-staining-positive and aerobic coccus with the ability to degrade petroleum bacterium, designated Y42^T, was isolated from the Lenghu oil field located in the northern margin of the Qaidam Basin. Phylogenetic and signature nucleotides analyses revealed that strain Y42^T belongs to the genus Planococcus. The multiple sequence alignments of 16S rRNA and housekeeping genes showed that strain Y42^T formed a distinct lineage with the other Planococcus clade. The average nucleotide identity (ANI) and DNA-DNA hybridization values (DDH) between strain Y42^T and the reference strains were 69.5-70.1 and 19.4-21.7%, respectively, which values were below the threshold for species delineation. The major fatty acids of strain Y42^T were anteiso-C_15:0. The respiratory quinone was MK-7 (71.8%) as the predominant menaquinone followed the MK-6 (28.2%) and the cell-wall hydrolysates contained LL-diaminopimelic acid. The polar lipid was composed of diphosphatidyl glycerol, phosphatidyl glycerol, phosphoglycolipid, aminophospholipid and four unidentified lipids. The peptidoglycan type was A4α (L-Lys-D-Glu). The strain Y42^T possessed larger genome (approximately 4 MB) and revealed obvious differences for the abundance of the COG categories compared with the other Planococcus bacteria. Also, the strain Y42^T also possessed more unique orthologous proteins. The structural characteristics of the strain Y42^T genome provided a competitive advantage for better survival in petroleum-polluted environments. Combined with the 16S rRNA gene and genome sequence, phenotypic as well as chemotaxonomic characterisations, strain Y42^T is considered to represent a novel species of the genus Planococcus, for which the name Planococcus lenghuensis sp. nov. be proposed. The type strain is Y42^T (= CGMCC 1.15921^T = JCM 32719^T).

Indiicoccus explosivorum gen. nov., sp. nov., isolated from an explosives waste contaminated site

A pink-pigmented, Gram-stain-positive, aerobic, coccoid-shaped bacterial strain, designated as S5-TSA-19^T, was isolated from an explosives contaminated site in Panchkula, Haryana, India. The 16S rRNA gene sequencing blast analysis indicated that the strain is a member of the family Planococcaceae with the highest sequence similarity to Planomicrobium soli XN13^T (96.1 %), followed by Planococcus maitriensis S1^T (95.6 %), Planococcus plakortidis DSM 23997^T (95.6 %), Planomicrobium flavidum ISL-41^T (95.6 %), Planococcus rifietoensis M8^T (95.5 %), Planococcus salinus LCB217^T (95.5 %) and Planococcus maritimus DSM 17275^T (95.5 %). Phylogenetic analysis based on 16S rRNA gene and whole-genome sequences (based on a conserved set of 400 proteins) retrieved the strain in a distinct branch indicating a separate lineage within the family Planococcaceae. Strain S5-TSA-19^T had a distinctive chemotaxonomic pattern comprising A4α type peptidoglycan based on l-Lys-d-Asp, iso-C15 : 0 as the major fatty acid, absence of phosphatidylethanolamine as a major lipid and MK-7 and MK-6 as the major menaquinones, differentiating it from the genera Planococcus and Planomicrobium, thus supporting the findings of molecular phylogeny. Further, strain S5-TSA-19^T was able to biotransform hexahydro-1,3,5,-trinitro-1,2,5-triazine (RDX) into nitrite derivatives under aerobic conditions in 2-4 days, whereas the closest reference strains did not possess this property. On the basis of polyphasic taxonomic characterization and a phylogenomics approach, strain S5-TSA-19^T is proposed as the type strain of a novel species in a novel genus for which the name Indiicoccus explosivorum gen. nov., sp. nov. is proposed (=JCM 31737^T=KCTC 33871^T=MTCC 12608^T).

Planococcus halotolerans sp. nov., isolated from a saline soil sample in China

A novel Gram-stain-positive, coccoid or short rod-shaped, moderate-orange-pigmented, halotolerant and psychrotolerant bacterium, designated strain SCU63^T, was isolated from a saline soil sample in China, and characterized by a polyphasic taxonomic approach. 16S rRNA gene sequence similarity of strain SCU63^T to species in the genera Planococcus and Planomicrobium ranged from 96.5 to 98.6 %. Phylogenetic trees as well as diagnostic signature nucleotides in the 16S rRNA gene sequence supported the view that this strain should be assigned to the genus Planococcus. Further, average nucleotide identity and digital DNA-DNA hybridization analyses confirmed the separate species status of strain SCU63^T relative to the closely related taxa. The isolate grew at 0-40 °C (optimum, 30-35 °C), at pH 6.5-9.0 (pH 7.0-7.5) and in the presence of 0-15 % (w/v) NaCl (3 %). The principal fatty acids were anteiso-C15 : 0, C16 : 1ω7c alcohol, iso-C16 : 0 and iso-C14 : 0, and the dominant isoprenoid quinones were MK-8 and MK-7. The peptidoglycan type was determined to be A4α (l-Lys-d-Glu), and the polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminophospholipid and one unidentified lipid. The DNA G+C content was 44.6 mol%. Based on the genotypic, phenotypic and chemotaxonomic data, strain SCU63^T can be classified as a novel species in the genus Planococcus, for which the name Planococcushalotolerans sp. nov. is proposed. The type strain is SCU63^T (=CGMCC 1.13628^T=KCTC 43001^T).