Guha Titir, Biswas Suparna Mandal
Agricultural & Ecological Research Unit, Biological Sciences Division, Indian Statistical Institute, 203, Barrackpore Trunk Road, Kolkata, 700 108, India.
Department of Biology, Indian Institute of Science Education and Research, Srinivasapuram, Yerpedu Mandal, Tirupati, 517619, Andhra Pradesh, India.
Curr Microbiol. 2025 May 3;82(6):275. doi: 10.1007/s00284-025-04253-7.
In recent years, seed endophytes have gained significant attention due to their impact on the ecology, health, and productivity of host plants. Extensive research is being conducted to explore novel endophytic bacteria for sustainable crop improvement. Manilkara zapota L. P. Royen (Sapotaceae) is a highly stress-tolerant tree widely cultivated in tropical countries, yet its associated endophytes remain unexplored. In this study, nine bacterial isolates were obtained from M. zapota seeds, of which three (LA2, LA4, and NS1) were selected based on their IAA production capability which ranged from 2.3, 6.34, and 16.1 µg mL, respectively. Identification through 16S rRNA sequencing confirmed LA2 as Pseudomonas rhodesiae, LA4 as Bacillus cereus, and NS1 as Enterobacter cloacae. All isolates exhibited nitrogen-fixing ability, while NS1 uniquely solubilized potassium and phosphorus with KSI and PSI value as 2.9 and 2.3, respectively. Further, the efficacy of the bacterial isolates in promoting rice seedling growth was evaluated, and novel bioformulation was prepared from the consortia of LA2 + LA4, LA2 + NS1, LA4 + NS1, and LA2 + LA4 + NS1. All the isolates and bioformulations were tested as biopriming agents. Rice seedling growth experiments revealed a significant increase in germination percentage, root length, and shoot length following biopriming with individual isolates and consortia. Among treatments, the LA2 + LA4 combination exhibited the highest growth promotion, with a root length increase of 2.1-fold and shoot length increase of 2.3-fold as compared to control. Thus, our results highlighted that bioprospecting microbes from M. zapota seeds can help in nutrient management and seedling establishment.
近年来，种子内生菌因其对宿主植物的生态、健康和生产力的影响而受到广泛关注。目前正在进行广泛的研究，以探索新型内生细菌，以实现可持续的作物改良。人心果（山榄科）是一种高度耐胁迫的树木，在热带国家广泛种植，但其相关内生菌仍未得到探索。在本研究中，从人心果种子中获得了9株细菌分离株，其中3株（LA2、LA4和NS1）因其IAA产生能力而被选中，其IAA产生能力分别为2.3、6.34和16.1 μg/mL。通过16S rRNA测序鉴定，LA2为罗得西亚假单胞菌，LA4为蜡样芽孢杆菌，NS1为阴沟肠杆菌。所有分离株均表现出固氮能力，而NS1独特地溶解了钾和磷，其KSI和PSI值分别为2.9和2.3。此外，评估了细菌分离株对水稻幼苗生长的促进效果，并由LA2+LA4、LA2+NS1、LA4+NS1和LA2+LA4+NS1组合制备了新型生物制剂。所有分离株和生物制剂均作为生物引发剂进行测试。水稻幼苗生长实验表明，用单个分离株和组合进行生物引发后，发芽率、根长和茎长均显著增加。在各处理中，LA2+LA4组合表现出最高的生长促进效果，与对照相比，根长增加了2.1倍，茎长增加了2.3倍。因此，我们的结果突出表明，从人心果种子中进行生物勘探微生物有助于养分管理和幼苗建立。
