The Predatory Myxobacterium Citreicoccus inhibens gen. nov. sp. nov. Showed Antifungal Activity and Bacteriolytic Property against Phytopathogens

Abstract

The application and promotion of biological control agents are limited because of poor efficacy and unstable performance in the field. Screening microorganisms with high antagonistic activity, effective adaptability, and high field-survival should be prospected. Myxobacteria are soil predatory bacteria with wide adaptability, which are considered as good antagonists. Here, we report a myxobacterium strain M34 isolated from subtropical forest soil in South China using the Escherichia coli baiting method. Based on the morphological observation, physiological test, biochemical characteristics, 16S rRNA gene sequence, and genomic data, strain M34 was identified as a novel genus and novel species, representing a new clade of Myxococcaceae, for which the name Citreicoccus inhibens gen. nov. sp. nov. is proposed (type strain M34T = GDMCC 1.2275T = KCTC 82453T). The typical features of M34, including fruiting body formation and extracellular fibrillar interconnection, indicated by microscopic observations, contributed to cell adaption in different environments. Furthermore, the strain showed antifungal activity against phytopathogenic fungi and predatory activity to both Gram-negative and Gram-positive phytopathogenic bacteria. The bioprotective mechanisms are attributed to the presence of pyrrolnitrin and derivative with antifungal activity and the extracellular proteins with lytic activity against pathogenic bacteria. Due to its multiple beneficial traits, strain M34 has the potential to be developed into a versatile biocontrol agent for the management of both fungal and bacterial phytopathogens.

Myxococcus xanthus R31 Suppresses Tomato Bacterial Wilt by Inhibiting the Pathogen Ralstonia solanacearum With Secreted Proteins

“…Interestingly, we found that Citreicoccus inhibens gen. nov. sp. nov. M34 suppressed or predated a variety of phytopathogen mainly by secreting secondary metabolisms (Zhou et al, 2021). Generally speaking, we speculate that this may be related to the differences between different species in the coevolution process of myxobacteria, plants, and microorganisms.…”

Characteristics of a lipase ArEstA with lytic activity against drug-resistant pathogen from a novel myxobacterium, Archangium lipolyticum sp. nov.

“…The predatory products of myxobacteria, including secondary metabolites and hydrases showing promising antimicrobial activities, have been reported ( Sasse et al, 2003 ; Zhou et al, 2021 ; Zhang et al, 2023b ). While most studies have focused on antibiotic production by myxobacteria, there are only a few reports about their enzymatic potential.…”

“…Based on the prey structure, macromolecule components found in the cell wall, cytomembrane, and nucleus are targets of lytic weapons from myxobacteria. In fact, myxobacteria genomes encode numerous peptidases, glycoside hydrolases, polysaccharide lyases, and carbohydrate esterases ( Schneiker et al, 2007 ; Zhou et al, 2021 ; Wang et al, 2022 ), which likely target the prey structure in the process of predation. For example, glycoside hydrolases from myxobacteria targeting peptidoglycan in Gram-positive bacteria or β-1,6-glucans in fungi cell walls have been characterized and shown to contribute to prey biomass disruption of predation ( Li et al, 2019 ; Arend et al, 2021 ).…”

Chromosomal organization of biosynthetic gene clusters suggests plasticity of myxobacterial specialized metabolism including descriptions for nine novel species:Archangium lansiniumsp. nov.,Myxococcus landrumussp. nov.,Nannocystis bainbridgeasp. nov.,Nannocystis poenicansasp. nov.,Nannocystis radixulmasp. nov.,Polyangium mundeleiniumsp. nov.,Pyxidicoccus parkwaysissp. nov.,Sorangium ateriumsp. nov.,Stigmatella ashevillenasp. nov

“…Myxobacteria are excellent resources for discovery of therapeutics and are suggested to be keystone taxa influencing polymicrobial community structure in soil (1,2, 66–68). Recent discoveries of novel Corallococcus, Myxococcus , and Pyxidicoccus species as well as species from lesser-studied genera indicate an abundance of uncharacterized myxobacteria (10–12, 14–17, 69–79). Our investigation of rhizospheric soil samples provided 20 environmental myxobacteria including 9 proposed novel species.…”