Marine Biotechnology Division, National Institute of Ocean Technology (NIOT), Ministry of Earth Sciences (MoES), Government of India, Pallikaranai, Chennai, 600100, India.
Department of Biochemistry, University of Madras, Navalar Nagar, Chepauk, Triplicane, Chennai, Tamil Nadu, 600005, India.
Curr Microbiol. 2024 Oct 14;81(12):405. doi: 10.1007/s00284-024-03890-8.
Arabian Sea is a highly productive Ocean owing to deep upwelling with reports on phosphorus cycling in ocean sediments. In this study, microbes from sea mounts of the Arabian Sea at varying depths (400 m, 900 m) were screened to isolate and characterize phosphate-solubilizing bacteria (PSB) with plant growth-promoting properties. Out of the seven morphologically different PSBs, two bacterial strains with maximum phosphate solubilization index were identified as Priestia megaterium (H1) and Bacillus velezensis (H2) based on biochemical and molecular characteristics. Different factors influencing phosphatase production were optimized, which showed maximum solubilization at temperature of 30 °C (97.5 μg/mL), glucose as best carbon source (70 µg/mL), 1-M NaCl (114.1 µg/mL), and pH 8 (134.3 µg/mL) indicating their halophilic and alkaliphilic characteristics. Alkaline phosphatase enzyme was extracted and partially purified from both PSBs wherein H2 strains showed greater specific activity (24.83 U/mg). Metabolomics studies through HPLC revealed maximum production of gluconic acid (483.75 mg/L) in addition to lactic, oxalic, acetic, and succinic acid during solubilization. Biopriming effect of PSBs on tomato seed germination showed high germination index (80%) in consortia of both isolates which was also validated through root colonization by SEM analysis. Further studies using pot assay experiments also showed comparable results in marine PSB consortia with positive control (Phosphobacteria) for plant growth attributes including root height and weight. These findings suggest that the halophilic PSB strains from marine sediments could be used as potential bio-inoculants to enhance plant growth and combat saline stress for sustainable Agriculture.
阿拉伯海是一个生产力极高的海洋，由于深层上升流，海洋沉积物中的磷循环已有相关报道。在这项研究中，从阿拉伯海海山的不同深度（400 m、900 m）筛选微生物，以分离和鉴定具有植物促生特性的溶磷细菌（PSB）。在 7 种形态不同的 PSB 中，根据生化和分子特征，有 2 株具有最大磷酸盐溶解指数的细菌菌株被鉴定为巨拟杆菌（H1）和贝莱斯芽孢杆菌（H2）。优化了影响磷酸酶产生的不同因素，结果表明在 30°C（97.5μg/mL）下最大溶解，葡萄糖作为最佳碳源（70μg/mL）、1-M NaCl（114.1μg/mL）和 pH 8（134.3μg/mL），表明它们具有嗜盐和嗜碱特性。从两种 PSB 中提取和部分纯化了碱性磷酸酶，其中 H2 菌株表现出更大的比活性（24.83 U/mg）。通过 HPLC 进行的代谢组学研究表明，在溶磷过程中除了乳酸、草酸、乙酸和琥珀酸外，还会产生最大量的葡萄糖酸（483.75mg/L）。PSB 对番茄种子萌发的生物引发效应表明，在两种分离物的混合物中，萌发指数（80%）较高，这也通过 SEM 分析对根定植进行了验证。进一步的盆栽试验研究也表明，在海洋 PSB 混合物中，与阳性对照（磷杆菌）相比，植物生长特性包括根高和根重具有相当的结果。这些发现表明，海洋沉积物中的嗜盐 PSB 菌株可以用作潜在的生物接种剂，以提高植物的生长并对抗盐胁迫，从而实现可持续农业。
