Aug 2026· Frontiers in Microbiology· 0 citations· 64 references
TL;DR
Strain SX92 T is proposed as the type strain of a novel species, Streptomyces songxianensis, and is established as a promising multifunctional biocontrol agent for sustainable tobacco production.
Abstract
Streptomyces
species are well-known for their potential in biocontrol and plant growth promotion, with the rhizosphere serving a rich reservoir for novel isolates. In this study, a
Streptomyces
strain (SX92
T
) was isolated from the rhizosphere of healthy tobacco plants. In dual-culture assays, SX92
T
displayed broad-spectrum antagonistic activity against six major fungal pathogens of tobacco, with the highest inhibition (59.22%) against
Phytophthora nicotianae
, the causal agent of tobacco black shank. Polyphasic taxonomic characterization, combining 16S rRNA gene phylogeny, distinctive physiological traits, chemotaxonomic markers (LL-diaminopimelic acid, major menaquinones MK-10(H₄) and MK-9(H₈), and predominant fatty acids anteiso-C₁₅:₀ and C₁₆:₀), and genome-based metrics (ANI and dDDH), clearly distinguished SX92
T
from its closest relatives. Accordingly, strain SX92
T
is proposed as the type strain of a novel species,
Streptomyces songxianensis
sp. nov. The genome of SX92
T
is 9.69 Mb in size with a G + C content of 71% and contains 26 biosynthetic gene clusters, including one showing 100% similarity to the albaflavenone cluster. In field trials, application of SX92
T
fermentation broth significantly improved tobacco agronomic traits and reduced black shank incidence by 44.97%. Furthermore, SX92
T
treatment reshaped the rhizosphere microbiome by enriching beneficial bacteria such as
Flavobacterium
and altering the relative abundance of specific fungi, including a reduction in the arbuscular mycorrhizal fungus
Rhizophagus irregularis
. It also shifted soil enzyme activities, with increased cellulase and decreased catalase levels. These findings establish
Streptomyces songxianensis
SX92
T
as a promising multifunctional biocontrol agent for sustainable tobacco production.
Three Gram-stain-positive, aerobic, non-motile, rod-shaped bacterial strains, designated LJC-15T, NGA-4T and QZ2-6-4T, were isolated from the rhizosphere soils of Capsicum, Cucurbita and Solanum melongena, respectively, in Yunnan Province, China and were proposed to represent three novel species of the genus Agromyces.
Z. Duan, Shuailiang Shi, Bang-Li Huang et al.· Microorganisms· 0 citations
Bioprospecting of plant growth-promoting bacteria enables the identification of beneficial microbial resources with significant potential for sustainable agricultural applications. In this context, strain TRQ48 was isolated from a commercial field of wheat (Triticum turgidum L. subsp. durum) located in the Yaqui Valley, Mexico, with the aim of exploring its plant growth-promoting potential. The draft genome sequence presented a genomic size of 2,777,016 bp, 32.5% G + C content, 665,763 bp N50, 2 L50, and 19 contigs. Taxonomic affiliation demonstrated that strain TRQ48 belonged to Mammaliicoccus sciuri. Genome annotation identified 2756 coding DNA sequences (CDS) distributed into 259 subsystems, highlighting CDS associated with iron acquisition and metabolism, stress response, and virulence, disease, and defense, among others. Metabolic assays reflect the strain’s capacity to produce siderophores and auxins, relating these positive traits to significantly (p ≤ 0.05) promote growth of wheat shoot length (7.09%) and root and shoot dry weight (75% and 18.43%) compared to uninoculated wheat plants. Biosafety testing indicated that the strain is susceptible to commonly used antibiotics and lacks clinically relevant resistance profiles, matching genomic analysis, which did not reveal any critical virulence factors. Thus, although the presented results show that M. sciuri TRQ48 is a promising beneficial biosafe strain, further studies are still needed to evaluate its performance under agro-ecosystems at commercial levels.
América Lizeth Sánchez-Zúñiga, Luis Alberto González-Vázquez, Alina Escalante-Beltrán et al.· Agronomy· 0 citations
India contributes 26% of global banana production, yet cultivation is severely threatened by Fusarium wilt (Fusarium oxysporum f. sp. cubense, Foc), necessitating sustainable, eco-friendly management strategies. This study evaluated the biocontrol potential of endophytic bacteria isolated from Foc-resistant and -susceptible banana cultivars. Isolates from the pseudostem, corm, and root of the resistant cultivar showed significantly greater inhibitory activity than those from the susceptible cultivar, underscoring the role of host genotype in shaping functionally competent endophytic communities. Among all isolates, Bacillus sp. from the corm of cv. Rose (AB) showed the highest mycelial inhibition of Foc (70.37–76.54%) in vitro. GC-MS-based metabolite profiling revealed a chemically diverse array of secondary metabolites, fatty acid esters, steroids, terpenoids, siloxanes, and nitrogenous compounds. Corm-associated endophytes exhibited membrane-disruptive and cytotoxic activity, while root-associated endophytes contributed protective, defense-modulatory effects. Halomonas sp. RoRo2 and B. subtilis RoC1 showed the highest inhibition in both agar-well and in planta assays, with unsaturated fatty acids and organic acid derivatives implicated as key antifungal effectors acting through multiple biochemical pathways. These findings identify metabolically versatile endophytes as promising candidates for developing efficient, environmentally compatible bioinoculants as sustainable alternatives to chemical control of Fusarium wilt in banana.
D. P. Mohite, Kavino Mathiyazhagan, Nakkeeran Sevugapperumal et al.· Pathogens· 0 citations
Findings establish B. velezensis strains BP5 and BP103 as highly promising biocontrol agents, combining high genetic stability with diverse secondary metabolite profiles, suitable for development into sustainable microbial bio-bactericides.
Lê Uyển Thanh, Vu Nhat Tan, T. Huyen et al.· Frontiers in Microbiology· 0 citations
Five Gram-negative, facultatively anaerobic bacteria were isolated from the hollow stalk tissues of tobacco plants in Yunnan, China. Based on polyphasic taxonomic data, they were identified as a new Pectobacterium species. Phylogenetic analyses of 16S rRNA and the concatenated dnaX-leuS-recA genes grouped them into a distinct monophyletic clade. Genome analyses showed high average nucleotide identity (ANIb 96.96–97.63%) and digital DNA-DNA hybridization (dDDH 76.2–80.1%) values, supporting their classification as a single species. However, three indices, including lower dDDH (67.9%), borderline ANIb (95.89%), and phylogenomic separation with 99% support, differentiate them from Pectobacterium brasiliense IPO 3540T. Comparative genomics across 24 reference strains revealed differences in virulence factors and specific plant cell wall-degrading enzyme profiles, highlighting adaptations to different hosts. Biochemical tests showed that all isolates lacked β-glucosidase and exhibited unique carbon utilization patterns; chemotaxonomically, strain 21LCBS03T produced only menaquinone MK-8. Pathogenicity experiments confirmed that four strains caused severe soft rot and hypersensitive responses on various hosts, while strain BSHS4, with a dDDH of 76.2% relative to 21LCBS03T, showed reduced virulence—possibly a subspecies. Reanalysis of 633 Pectobacterium genomes from NCBI reclassified 121 strains into this new species, exposed common misidentifications, and identified 9 candidate novel species awaiting phenotypic validation. Combining phylogenomic, virulence, phenotypic, and pathogenic data, we propose Pectobacterium nicotianae sp. nov., with 21LCBS03T (=GDMCC 1.3317T = CCTCC AB2022131T = JCM 35650T) designated as the type strain.
Can-Hua Lu, Xiaofang Lu, Hou-Fa Zhou et al.· Frontiers in Plant Science· 0 citations
In this work, genes and biosynthetic pathways linked to secondary metabolite production, biocontrol activity, and plant interactions were identified and supported the experimentally validated capability of DEF39 to protect plants from fungal diseases, highlighting the potential of genomics studies.
Irene Valenti, A. Motta, M. Saracchi et al.· BMC Genomic Data· 0 citations
