Growth and functional evaluation of Enterobacter cloacae under salinity stress

Soil salinization is a serious threat world is facing and is a major concern for land degradation and it affects both plant and microbial life. Salinity hampers bacterial growth and lowers soil bacterial activity by inducing osmotic stress and ion toxicity. The salt tolerant bacteria present in soil possessing several plant growth promoting (PGP) attributes like phosphate solubilization and production of growth hormones are crucial for fertility of soil and boosting plant growth. Such salt tolerant bacterial species reduce the osmotic stress by synthesizing compatible osmolytes to maintain their metabolism and cellular integrity. Understanding the effects of salinity on such bacterial species is important as their survival under salt stress gives double benefits one the bacterial diversity is maintained, and secondly the growth and development of plants is also improved under salinity stress. With this aim in the present study Enterobacter cloacae BHUAS1 was tested for its phosphate solubilization potential and its mechanisms under salinity stress along with other PGP traits such as indole-3- acetic acid (IAA), siderophore, hydrogen cyanide (HCN), ammonia production and zinc solubilization under in vitro condition. E. cloacae BHUAS1 exhibited significant PGP traits and was able to generate soluble phosphate (26.49 mg/L to 32.68 mg/L), IAA (23.35-105.78 mg/L), siderophore (43.782-65.414 % SU), organic acids (3.39-110.30 mg/L), ammonia (0.21-0.44 mu M/ml) and proline (16-38.96 mg/L) under various treatments. In addition to this, E . cloacae BHUAS1 also exhibited production of HCN and zinc solubilization. The results obtained put forward the possible application of E . cloacae BHUAS1 in saline soils for improving plant growth.