2_Bacillus siamensis to restore the compromised amino acid and energy metabolism of Mesorhizobium metallidurans under saline alkali stress

These findings suggest that B. siamensis BT 9 1 cross-feeds M. metallidurans YC-39 with these metabolites, rescuing the compromised branched-chain amino acid synthesis pathway and the TCA cycle in saline alkaline environments. Eventually, coinoculation with B. siamensis BT 9 1 and M. metallidurans YC 39, along with isopropylmalate and succinic acid supplementation, increased M. metallidurans YC 39 nodule colonization and nitrogenase activity. Our study offers fresh perspectives on how wild S. davidii recruits beneficial Bacillus species to provide key metabolites for M. metallidurans, thereby increasing rhizobial survival under saline alkaline stress.