Unveiling the complete genome sequence of Paenibacillus taichungensis: genomic features and biocontrol potential

OBJECTIVES

The genus Paenibacillus encompasses a diverse group of Gram-positive bacteria with significant biotechnological potential. However, the research data and application cases of Paenibacillus taichungensis were still poorly understood. In this study, we isolated a P. taichungensis strain BB507, which demonstrated antibacterial effect on Ralstonia solanacearum species complex, and provided data and analysis of its complete genome.

DATA DESCRIPTION

Strain BB507 was isolated from a pine rhizosphere in Meizhou city, Guangdong province of China, and showed antibacterial activity against Ralstonia solanacearum species complex. Complete genome was sequenced using Illumina NovaSeq (second-generation) and Oxford Nanopore (third-generation) platforms. The genome of BB507 comprised of a 6,974,531 bp circular chromosome and a 352,197 bp circular plasmid, encoding a total of 6,649 gene with an average gene length of 950 bp, 103 transfer RNAs, 2 sRNAs, and 36 rRNAs. Three candidate CRISPRs, 6 genomic islands and 14 prophages were predicted. The bacterial orthologous average nucleotide identity (OAT) and the type genome server (TYGS) analysis highlighted the strain BB507 was clustered into a subgroup with P. taichungensis. antiSMASH v7.0 predicted the presence of 10 secondary metabolite gene clusters in the genome. These findings will serve as a useful resource for further research in industrial and agricultural biotechnology.

Isolation and characterization of salt-stress-tolerant rhizosphere soil bacteria and their effects on plant growth-promoting properties

PGPR has a higher potential impact on agricultural crops. It enhances plant growth and development in a variety of adverse environmental conditions, including biotic and abiotic stresses. The PGPR is commercially vital since it is more efficient, safe for the environment, and beneficial to the economy. Nowadays, salt stress has an impact on the agricultural ecosystem. Salt-tolerant PGPR can directly stimulate plant growth and development by producing a variety of metabolites and phytohormones. The current study looked at the isolation of salt-tolerant bacterial species and their ability to stimulate plant development. Four bacterial species were chosen for their better salt stress tolerance (0-5%). They were identified by 16S rRNA sequencing: Solibacillus silvestris BR1, Peribacillus frigoritolerans BR2, Paenibacillus taichungensis CR1, and Solibacillus isronensis CR2. These strains were positive production of indole acetic acid with varying incubation periods (19.66 ± 1.528 to 646.111 ± 8.058 µg/mL), salt stress (ranging from 29.556 ± 1.171 to 147.8111 ± 2.086 µg/mL), phosphate solubilization (0.145 ± 0.011 to 0.921 ± 0.007 µg/mL), ammonium production (0.299 ± 0.047 to 1.202 ± 0.142 µg/mL), HCN production (0.308 ± 0.051 to 4.269 ± 0.069 µg/mL), and siderophore production (0.190 ± 0.064 to 1.543 ± 0.108 µg/mL) for control strains were used without salt stress. The production level was expressed using a standard curve containing various standards.

As(III) Exposure Induces a Zinc Scarcity Response and Restricts Iron Uptake in High-Level Arsenic-Resistant Paenibacillus taichungensis Strain NC1

The Gram-positive bacterium Paenibacillus taichungensis NC1 was isolated from the Zijin gold-copper mine and shown to display high resistance to arsenic (MICs of 10 mM for arsenite in minimal medium). Genome sequencing indicated the presence of a number of potential arsenic resistance determinants in NC1. Global transcriptomic analysis under arsenic stress showed that NC1 not only directly upregulated genes in an arsenic resistance operon but also responded to arsenic toxicity by increasing the expression of genes encoding antioxidant functions, such as cat, perR, and gpx. In addition, two highly expressed genes, marR and arsV, encoding a putative flavin-dependent monooxygenase and located adjacent to the ars resistance operon, were highly induced by As(III) exposure and conferred resistance to arsenic and antimony compounds. Interestingly, the zinc scarcity response was induced under exposure to high concentrations of arsenite, and genes responsible for iron uptake were downregulated, possibly to cope with oxidative stress associated with As toxicity. IMPORTANCE Microbes have the ability to adapt and respond to a variety of conditions. To better understand these processes, we isolated the arsenic-resistant Gram-positive bacterium Paenibacillus taichungensis NC1 from a gold-copper mine. The transcriptome responding to arsenite exposure showed induction of not only genes encoding arsenic resistance determinants but also genes involved in the zinc scarcity response. In addition, many genes encoding functions involved in iron uptake were downregulated. These results help to understand how bacteria integrate specific responses to arsenite exposure with broader physiological responses.

Paenibacillus sinensis sp. nov., a nitrogen-fixing species isolated from plant rhizospheres

Two strains HN-1^T and 39 were isolated from rhizospheres of different plants grown in different regions of PR China. The two strains exhibited high nitrogenase activities and possessed almost identical 16S rRNA gene sequences. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two strains were 99.9 and 99.8%, respectively, suggesting that they belong to one species. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strains HN-1^T and 39 are the members of the genus Paenibacillus and both strains exhibited 99.5% similarity to Paenibacillus stellifer DSM 14472^T and the both strains represented a separate lineage from all other Paenibacillus species. However, the ANI of type strain HN-1^T with P. stellifer DSM 14472^T was 90.69, which was below the recommended threshold value (< 95-96% ANI). The dDDH showed 42.1% relatedness between strain HN-1^T and P. stellifer DSM 14472^T, which was lower than the recommended threshold value (dDDH < 70%). The strain HN-1^T contain anteiso-C_15:0 as major fatty acids and MK-7 as predominant isoprenoid quinone. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, four aminophospholipids and an unidentified glycolipid. Unlike the most closely related P. stellifer DSM 14472^T, strain HN-1^T or 39 was positive for catalase reaction. Distinct phenotypic and genomic characterisations from previously described taxa support the classification of strains HN-1^T or 39 as representatives of a novel species of the genus Paenibacillus, for which the name Paenibacillus sinensis is proposed, with type strains HN-1^T (=CGMCC 1.18902, JCM 34,620), and reference strain 39 (=CGMCC 1.18879, JCM 34,616), respectively.

Identification and Control of Latent Bacteria in in vitro Cultures of Sweetpotato [Ipomoea batatas (L.) Lam]

Bacterial microorganisms which are latent in in vitro cultures can limit the efficiency of in vitro methods for the conservation of genetic resources. In this study we screened 2,373 accessions from the in vitro sweetpotato germplasm collection of the International Potato Center in Lima, Peru for bacteria associated with plantlets in tissue culture through a combination of morphological methods and partial 16S rDNA sequencing. Bacteria were detected in 240 accessions (10% of the accessions screened) and we were able to isolate 184 different bacterial isolates from 177 different accessions. These corresponded to at least nineteen Operational Taxonomic Units (OTUs) of bacteria, belonging to the genera Sphingomonas, Bacillus, Paenibacillus, Methylobacterium, Brevibacterium, Acinetobacter, Microbacterium, Streptomyces, Staphylococcus, and Janibacter. Specific primers were developed for PCR based diagnostic tests that were able to rapidly detect these bacteria directly from tissue culture plants, without the need of microbial sub-culturing. Based on PCR screening the largest bacterial OTUs corresponded to a Paenibacillus sp. closely related to Paenibacillus taichungensis (41.67%), and Bacillus sp. closely related to Bacillus cereus (22.22%), and Bacillus pumilus (16.67%). Since in vitro plant genetic resources must be microbe-free for international distribution and use, any microbial presence is considered a contamination and therefore it is critical to clean all cultures of these latent-appearing bacteria. To accomplish this, plantlets from in vitro were transferred to soil, watered with Dimanin^® (2 ml/l) weekly and then reintroduced into in vitro. Of the 191 accessions processed for bacterial elimination, 100% tested bacteria-free after treatment. It is suspected that these bacteria may be endosymbionts and some may be beneficial for the plants.

Paenibacillus xylanivorans sp. nov., a xylan-degrading bacterium isolated from decaying forest soil

A xylanolytic bacterial strain, named A59^T, was isolated from a forest soil consortium in southern Argentina. Strain A59^T is a Gram-stain-positive, facultative anaerobic, endospore-forming and rod-shaped bacterium. Its optimal growth conditions are 30 °C (range, 28-37 °C), pH 7 (range, pH 5-10) and it tolerates up to 7 % of NaCl (range, 2-7 %). Chemotaxonomic analysis revealed that strain A59^Tpossesses meso-diaminopimelic acid in the cell wall. It contains menaquinone MK-7 as the predominant isoprenoid quinone and the major fatty acid is anteiso-C_15 : 0 (35.1 %), with a moderate amount of C_16 : 0 (6.9 %). According to 16S RNA gene sequence analysis, the isolate is phylogenetically placed in the same cluster as Paenibacillus taichungensis BCRC 17757^T (99.7 % nucleotide sequence identity) and Paenibacillus pabuli NBRC 13638^T (99.1 %) and is closely related to Paenibacillus tundrae A10b^T (98.8 %). However, phylogenetic studies based on the housekeeping gyrB gene placed A59^T in a separate branch from all other related type strains. Furthermore, the results of whole genome average nucleotide identity analysis (gANI) with related type strains was lower than 91.10 % and the digital DNA-DNA hybridization value was lower than 44.30 %, which are below the threshold values for separating two species. The DNA G+C content was estimated as 46.09 mol%, based on genome sequencing. On the basis of these results, A59^T represents a new species of the genus Paenibacillus, and we propose the name Paenibacillusxylanivorans sp. nov. The type strain is A59^T (=DSM 107920^T=NCIMB 15123^T).

Paenibacillusliaoningensis sp. nov., isolated from soil

A novel bacterial strain, designated as LNUB461T, was isolated from soil sample taken from the countryside of Shenyang, Liaoning Province, China. The isolate was a Gram-stain-positive, aerobiotic, motile, endospore-forming and rod-shaped bacterium. The organism grew optimally at 30-33 °C, pH 6.5-7.0 and in the absence of NaCl. Phylogenetic analysis based on the nearly full-length 16S rRNA gene sequence revealed high sequence similarity with Paenibacillus algorifonticola XJ259T (98.5 %), Paenibacillus xinjiangensis B538T (96.8 %), Paenibacillus glycanilyticus DS-1T (96.1 %) and Paenibacillus lupini RLAHU15T (96.1 %). The predominant cellular fatty acid and the only menaquinone were anteiso-C15:0 and MK-7, respectively. The main polar lipids of LNUB461T included phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylcholine (PC) and two unknown amino phospholipids (APL), and the cell-wall peptidoglycan was meso-diaminopimelic acid (A1γ). The DNA G+C content of LNUB461T was 49.1 mol%. The DNA-DNA hybridization value between LNUB461T and the most closely related species (P. algorifonticola) was 41.8 %. On the basis of these data, LNUB461T was classified as representing a novel species of the genus Paenibacillus, for which the name Paenibacillus liaoningensis sp. nov was proposed. The type strain is LNUB461T (=JCM 30712T=CGMCC 1.15101T).

Bacillus taiwanensis sp. nov., isolated from a soil sample from Taiwan

A Gram-stain-positive, rod-shaped, endospore-forming, aerobic bacterium (FJAT-14571T) was isolated from a soil sample in Taiwan. Strain FJAT-14571T grew at 20–40 °C (optimum 35 °C), pH 6–10 (optimum pH 8) and 0–2 % (w/v) NaCl (optimum 0 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain FJAT-14571T was a member of the genus Bacillus and was most closely related to Bacillus oceanisediminis DSM 24771T (96.2 %). DNA–DNA relatedness between strain FJAT-14571T and B. oceanisediminis DSM 24771T was low (32.0 % ± 0.88 %). The diagnostic diamino acid of the peptidoglycan of strain FJAT-14571T was meso-diaminopimelic acid and the predominant menaquinone was MK-7 (96.6 %). The major cellular fatty acids were iso-C15 : 0 (46.4 %), anteiso-C15 : 0 (7.6 %), iso-C17 : 0 (8.2 %) and iso-C16 : 0 (10.0 %) and the DNA G+C content was 40.8 mol%. Phenotypic, chemotaxonomic and genotypic properties clearly indicated that strain FJAT-14571T represents a novel species within the genus Bacillus, for which the name Bacillus taiwanensis sp. nov. is proposed. The type strain is FJAT-14571T ( = DSM 27845T = CGMCC1.1 2698T).

Paenibacillus oceanisediminis sp. nov. isolated from marine sediment

A Gram-stain-negative, non-motile, aerobic, endospore forming and rod-shaped bacterium, designated strain L10(T), was isolated from marine sediment collected from the South Korean coast. The organism grew optimally under conditions of 30 °C, 1 % (w/v) NaCl and pH 6.0. It was oxidase-negative and catalase-positive. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain L10(T) was associated with the genus Paenibacillus and most closely related to Paenibacillus barcinonensis BP-23(T) (98.2 % similarity). The major fatty acids of strain L10(T) were iso-C(14 : 0), anteiso-C(15 : 0) and iso-C(16 : 0). The cell-wall peptidoglycan was the A1γ type, and the predominant isoprenoid quinone was menaquinone-7. Strain L10(T) contained two unidentified lipids, an unidentified amino-phospholipid, phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. The G+C content of the genomic DNA was 44 mol% and the DNA-DNA hybridization values with closely related strains were below 14±2 %. Based on phenotypic, genotypic, and phylogenetic data, strain L10(T) should be classified as a novel species within the genus Paenibacillus. The name Paenibacillus oceanisediminis sp. nov. is proposed. The type strain is L10(T) ( = KACC 16203(T) = JCM 17814(T)).