GENE ANALYSIS OF THE GROWTH-PROMOTING FUNCTION OF Paenibacillus mucilaginosus ON GREENHOUSE TOMATO

Paenibacillus mucilaginosus is a typical plant growth-promoting rhizobacterium. However, the relevant molecular mechanisms remain obscure. This study investigated the effect of Paenibacillus mucilaginosus PM12 on tomato growth and uncovered the bacterium's physiological processes. A greenhouse experiment was conducted, which included the PM12 group (3.2*10(8) cfu/pot) and the control group (inoculated with the same amount of sterilized suspension). The metabolomics of the centrifuged supernatant of the fermentation broth of Paenibacillus mucilaginosus was studied by LCMS, and the metabolite composition of the functional bacteria and its metabolic pathway were determined. PacBio+Illumina HiSeq sequencing was used to complete map sequencing of the samples. Indepth analysis of the functional genes related to the secretion of these substances by functional bacteria was conducted. PM12 significantly promoted the tomato growth, early flowering time and increased fruiting. Extracellular metabolite composition analysis showed that PM12 secreted organic acids to dissolve phosphorus, capsular polysaccharides to dissolve potassium, and auxin. The complete genome sequence indicated that the strain comprised one circular chromosome with 8,660,710 bases containing 58.51% GC content and 85.67% coding regions. Four genes (pyk, ackA, gltA and aroK) were related to organic acid secretion, four genes (pelA, pelD, pelf and pelG) were related to capsular polysaccharide secretion, and four genes (trpA, trpB, trpS and idi) were related to auxin secretion. The molecular biological mechanism of the extracellular secretion of organic acids to dissolve phosphorus, capsular polysaccharides to dissolve potassium and auxin to promote the growth of the PM12 strain was elucidated.