Unlocking phosphorus in saline environments: simplified bacterial communities enhance P cycling and maize growth

Salinity stress is a significant global challenge to crop productivity as it disrupts the phosphorus (P) cycle. To address this issue, we investigated halotolerant bacteria with P-solubilizing capabilities as a sustainable solution to enhance P cycling and promote maize growth under salinity stress. This study evaluated the efficacy of three simplified bacterial communities (SC1, SC2, and SC3) composed of Arthobacterium sp., Brevibacterium sp., Salinicola tamaricis, Nitratireductor aquibiodomus, and Staphylococcus sciuri, which were isolated from the coastal regions of Java. These SCs were selected based on their compatibility with plant growth-promoting (PGP) traits. The inoculation of SC substantially improved the growth and physiological responses of maize plants in vitro and greenhouse testing. Notably, SC3 and SC1, characterized by a high ability for P solubilization and IAA production, showed greater maize growth and biomass production, along with improved physiological responses. Specifically, SC1-inoculated plants showed the highest increase in chlorophyll content of approximately 40.0% higher than saline uninoculated plants. Meanwhile, SC3 showed the most significant increases in osmo-protectants, such as soluble sugars (17.5%) and proline (17.8%), compared to the saline uninoculated plants. Moreover, these improvements were associated with enhanced soil P availability and plant P uptake in both SCs. Our study indicates that simplified bacterial communities can maintain maize performance and support P cycling under saline stress, which may be useful as a versatile bioinoculant for saline environments.