ACC deaminase producing Plant growth promoting rhizobacteria (PGPR) offers a great promise for ameliorating the negative impacts of salinity stress manifested on plants. In this context, 28 rhizospheric bacteria associated with ACC deaminase potential (198−1069 nmol α-ketobutyrate mg protein⁻¹ h⁻¹) were isolated from 5 different islands of Lakshadweep, union territory, India- Agatti, Kavaratti, Bangaram, Kadmat, and Thinnakara islands using DF-minimal medium. The diversity of cultivable ACC deaminase producing bacteria was analysed by PCR-RFLP (Restriction Fragment Length Polymorphism) method using three endonucleases AluI, MspI and HaeIII which led to the grouping of these isolates into six clusters at 80 % similarity index. Subsequently, isolates were functionally characterized for various PGP traits such that indole-3-acetic acid (IAA) production (∼10−80 μg mL⁻¹); 16 isolates had phosphate solubilizing potential ranging from ∼19 to 88 P mg L⁻¹ ; siderophore and ammonia production abilities were observed in 5 and 24 isolates, respectively while two strains tolerated up to 8% NaCl. Phylogenetic analysis of 16S rRNA gene sequences of representative strain from each cluster revealed that twenty-eight ACC deaminase producing PGPR belong to eight distinct genera: Pseudomonas, Bacillus, Azospirillum, Azotobacter, Escherichia, Paenibacillus, Burkholderia, and Klebsiella. Two isolates, CO1 (Pseudomonas putida) and CO8 (Bacillus paramycoides) were evaluated for plant growth promoting effects on French bean (Phaseolus vulgaris) under salinity (100 mM NaCl) stress. Both the selected isolates in consortium form significantly increased the root length, shoot length, root fresh and dry weight, shoot fresh and dry weight of French bean seedlings exposed to salinity stress, compared to non-inoculated control plants. The co-inoculation with selected strains CO1 and CO8 has significantly improved chlorophyll concentration, relative water content, membrane stability index, gas exchange parameters including net photosynthesis rate (P_N), stomatal conductance (g_s), transpiration rate (E) and water use efficiency of French bean plants by ∼100 %, ∼85 %, ∼40 %, ∼198 %, ∼80 %, ∼70 % and ∼75 %, respectively under saline conditions in comparison with non-inoculated plants. Moreover, the consortium treated French bean plants showed lower levels of stress-induced ethylene by 38 %, electrolyte leakage and Malondialdehyde (MDA) content by ∼15 % under salt stress compared to non-inoculated ones. This study unveiled the potential of halotolerant strains, Pseudomonas putida and Bacillus paramycoides as French bean biofertilizers in mitigating the adverse effects of salinity in plant growth in sustainable agriculture.

产生 ACC 脱氨酶的植物生长促进根际细菌 (PGPR) 为减轻盐分胁迫对植物的负面影响提供了广阔的前景。在这种情况下，与相关联的ACC 28种际细菌脱氨酶的电位（198-1069纳摩尔α酮丁酸mg蛋白质^-1  ħ ^-1）购自洛克沙威，工会领土，印度-阿格蒂，卡瓦拉蒂，Bangaram，Kadmat的5个不同的岛屿分离和 Thinnakara 岛使用 DF 最小介质。使用三种核酸内切酶AluI、MspI和HaeIII通过 PCR-RFLP（限制性片段长度多态性）方法分析可培养的 ACC 脱氨酶细菌的多样性这导致将这些分离株以 80% 的相似性指数分为六个簇。随后，分离株被功能表征为各种 PGP 性状，例如吲哚-3-乙酸 (IAA) 产量（~10-80 μg mL ^-1）；16 个分离株具有溶解磷酸盐的潜力，范围为 ∼19 至 88 P mg L ^-1；分别在 5 个和 24 个分离株中观察到铁载体和氨产生能力，而两个菌株耐受高达 8% 的 NaCl。来自每个簇的代表性菌株的 16S rRNA 基因序列的系统发育分析表明，28 种产生 ACC 脱氨酶的 PGPR 属于 8 个不同的属：假单胞菌属、芽孢杆菌属、固氮螺菌属、固氮菌属、大肠杆菌，芽孢杆菌，类鼻疽，和克雷伯氏菌。评估了两种分离株 CO1 (恶臭假单胞菌) 和 CO8 (副真菌芽孢杆菌) 对法国豆 ( Phaseolus vulgaris ) 的植物生长促进作用) 在盐度 (100 mM NaCl) 压力下。与未接种的对照植物相比，以联合形式选择的两种分离株都显着增加了暴露于盐分胁迫的法国豆幼苗的根长、枝条长度、根鲜重和干重、枝条鲜重和干重。与选定菌株 CO1 和 CO8 共同接种显着提高了叶绿素浓度、相对含水量、膜稳定性指数、气体交换参数，包括净光合速率 (P _N )、气孔导度 (g _s), 法国豆植物的蒸腾速率 (E) 和水分利用效率分别在盐分条件下提高了 ~100%、~85%、~40%、~198%、~80%、~70% 和~75%，相比之下与未接种的植物。此外，与未接种的植物相比，在盐胁迫下，财团处理的法国豆植物的应激诱导乙烯水平降低了 38%，电解质泄漏和丙二醛 (MDA) 含量降低了约 15%。这项研究揭示了耐盐菌株恶臭假单胞菌和副杆菌作为法国豆生物肥料在减轻盐度对可持续农业中植物生长的不利影响方面的潜力。