Insight Into Genes Involved in the Production of Extracellular Chitinase in a Biocontrol Bacterium Lysobacter enzymogenes C-3

Abstract

The chitinase producing Lysobacter enzymogenes C-3 has previously been shown to suppress plant pathogens in vitro and in the field, but little is known of the regulation of chitinase production, or its role in antimicrobial activity and biocontrol. In this study, we isolated and characterized chitinase-defective mutants by screening the transposon mutants of L. enzymogenes C-3. These mutations disrupted genes involved in diverse functions: glucose-galactose transpoter (gluP), disulfide bond formation protein B (dsbB), Clp protease (clp), and polyamine synthase (speD). The chitinase production of the SpeD mutant was restored by the addition of exogenous spermidine or spermine to the bacterial cultures. The speD and clp mutants lost in vitro antifungal activities against plant fungal pathogens. However, the gluP and dsbB mutants showed similar antifungal activities to that of the wild-type. The growth of the mutants in nutrient rich conditions containing chitin was similar with that of the wild-type. However, growth of the speD and gluP mutants was defective in chitin minimal medium, but was observed no growth retardation in the clp and dsbB mutant on chitin minimal medium. In this study, we identified the four genes might be involved and play different role in the production of extracellular chitinase and antifungal activity in L. enzymogenes C-3.

Microbial diversity composition of apple tree roots and resistance of apple Valsa canker with different grafting rootstock types

“…For example, Rhizobia had a good inhibition on many soilborne plant pathogenic fungi belonging to different genera like Fusarium, Rhizoctonia, Sclerotium and Macrophomina [ 47 ]. Lysobacter can inhibit all kinds of pathogenic bacteria and fungi [ 48 , 49 ]. Variovorax paradoxus and Streptomyces scabrisporus were also effective biocontrol bacteria, which could restrain the invasion of some pathogenic bacteria and have a positive effect on plant growth [ 50 ].…”

Enhanced heat stable antifungal factor production by Lysobacter enzymogenes OH11 with cheap feedstocks: medium optimization and quantitative determination

“…This might be because L. enzymogenes can secrete a variety of extracellular hydrolases to digest various sugars, such as chitinase, proteases, cellulases, β ‐1,3‐glucanase (Choi et al . ), but no xylulokinase involved in xylose utilization (protein blast). For the organic carbon sources (citric acid and glycerol), a negative effect was observed in cell growth and the accumulation of HSAF.…”

Characterization of <i>Lysobacter enzymogenes</i> B25, a potential biological control agent of plant-parasitic nematodes, and its mode of action

“…On the other hand, the main metabolite conferring L. enzymogenes antibacterial activity is the cyclic depsipeptide WAP-8294A2, which selectively recognizes menaquinone present in the cytoplasmic membrane of gram-positive bacteria leading to the disruption and lysis of the membrane [21] . Moreover, L. enzymogenes secretes numerous extracellular lytic enzymes, such as chitinases, proteases, and lipases, which are able to degrade the major cell wall components of various phytopathogenic fungi, oomycetes, bacteria or nematodes, causing their death [17] , [22] , [23] .…”