Work

Effects of Bacillus velezensis inoculant on crop yield and microbial communities of muskmelon in South China

Year: 2026

Type: article

Abstract: Bacillus velezensis is a plant-growth-promoting bacterium with considerable potential to enhance soil nutrient availability and crop nutrient uptake. To elucidate the microecological and molecular mechanisms underlying its growth-promoting effects in muskmelon, a field experiment compared inactivated B. velezensis (CK) with live B. velezensis biofertilizer (BV). We systematically analyzed rhizosphere soil nutrients, enzyme activities, yield, and fruit quality, combined with high-throughput sequencing and non-targeted metabolomics. BV treatment increased muskmelon yield by 31.67% and elevated fruit contents of soluble sugars, soluble proteins, and vitamin C. It also significantly restructured microbial communities in the rhizosphere and root endosphere. Functional genera such as Actinomadura and Luteitalea , involved in organic matter decomposition and nutrient activation, were enriched in the rhizosphere. Beneficial bacteria such as Chryseobacterium and Pseudomonas , associated with phosphorus solubilization, nitrogen fixation, and stress resistance, were enriched in the root endosphere. These microbial shifts drove soil nutrient optimization, significantly increasing NO 3 ⁻ –N and available phosphorus by 42.06% and 34.34%, respectively ( P < 0.05). Key enzyme activities (URE, CAT, INV) were upregulated, enhancing carbon and nitrogen transformation. Metabolomic analysis revealed upregulation of organic nitrogen compounds, nucleotides, and signaling molecules such as benzothiazepines and saccharolipids, while phenylpropanoid biosynthesis was downregulated, indicating a metabolic shift from defense to growth promotion. Integrated multi-omics revealed that BV established a “microbe–soil–metabolite” network, where microbial communities correlated positively with soil nutrients and beneficial metabolites, synergistically improving nutrient cycling and energy metabolism. This study demonstrates that B. velezensis enhances muskmelon yield and quality by restructuring functional microbiota, activating soil enzymes and nutrient cycling, and reprogramming metabolic resource allocation, thereby optimizing the rhizosphere microecosystem.

Source: Scientia Horticulturae

DOI: 10.1016/j.scienta.2026.114678