LC-MS Metabolomics Reveals No Significant Impact of Microbial Inoculation with Bacillus velezensis and Lachnum sp. on Cranberry Metabolome

Sustainable agriculture has driven increased exploration of microbial inoculants as a promising strategy to boost plant growth for higher yield and enhance secondary metabolism to increase crop nutritional value. However, their influence on fruit-specific metabolites under field conditions remains understudied. This study investigated the impact of inoculating cranberry (Vaccinium macrocarpon) plants with Bacillus velezensis EB37 and Lachnum sp. EC5, applied individually and in combination, on cranberry fruit phytochemistry. Over two growing seasons (2019 and 2021), cranberries were collected from treated and control plots and analysed using untargeted and targeted LC-MS-based metabolomics. Multivariate analysis revealed no significant metabolomic differences due to treatments. However, samples clustered strongly by year of harvest, highlighting a pronounced environmental effect. Quantitative analysis of six representative phenolic compounds: chlorogenic acid, catechin, p-coumaric acid, phloridzin, myricetin, and quercetin, showed no statistically significant differences between treated and control cranberries. These findings indicate that microbial inoculation alone does not alter cranberry fruit metabolome, including phenolic levels, at field conditions. This study underscores how multiple factors, such as environmental conditions, can affect the outcome of microbial inoculation under field conditions and suggests that additional interventions may be required to achieve microbiome-based improvements in cranberry fruit quality.