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.
Highlights
Crop yield and quality are seriously affected by plant diseases
Strain M34 was isolated from the subsoil of a subtropical forest in South China, using the standard E. coli baiting method for myxobacteria isolation
Testing for growth at different temperatures demonstrated that M34 grew at a temperature of 25~40 ◦ C, which showed a relatively higher high-temperature tolerance than the closely related species from Corallococcus according to Livingstone et al [22]
Summary
Crop yield and quality are seriously affected by plant diseases. About 90% of the known infectious diseases of plants are caused by fungi and bacteria [1,2]. According to the data from Secretariat of the International Plant Protection Convention at the FAO, the amount of crop loss caused by plant disease was 14.1% [3]. Agricultural crops are treated with chemicals in most cases. Most of the chemical agents show high efficiency and persistence, many of them are toxic, harmful to environment, and sometimes even facing the risk of acquired resistance [4,5]. The development of efficient and eco-friendly alternatives focused on the elimination or reduction of synthetic chemicals in crop production is needed. Organic farming is widely accepted, and alternatives to the use of chemicals are most acceptable and
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