Mahmud F M Ashik, Islam Md Aminul, Rubel Mehede Hassan, Mukharjee Sanjoy Kumar, Kumar Manish, Bhattacharya Prosun, Ahmed Firoz
Department of Microbiology, Noakhali Science and Technology University, Noakhali 3814, Bangladesh.
Advanced Molecular Lab, Department of Microbiology, President Abdul Hamid Medical College, Karimganj, Kishoreganj-2310, Bangladesh; COVID-19 Diagnostic Lab, Department of Microbiology, Noakhali Science and Technology University, Noakhali 3814, Bangladesh.
Sci Total Environ. 2023 Sep 20;892:163774. doi: 10.1016/j.scitotenv.2023.163774. Epub 2023 May 23.
Avirulent halotolerant plant growth-promoting rhizobacteria (HPGPR) located on the roots' periphery can reduce abiotic stressors (such as salinity and drought), enhance plant productivity. Salinity poses a significant challenge for growing agricultural products, like rice, in the coastal regions. It is crucial to enhance production because of limited arable land and the high growth rate of the population. This study targeted to identify HPGPR from legume root nodules and assessed their effects on rice plants experiencing salt stress in coastal regions of Bangladesh. Based on the culture morphology, biochemical, salt, pH, and temperature tolerance traits, sixteen bacteria were isolated from the root nodules of leguminous plants (Common bean, Yardlong bean, Dhaincha, and Shameplant). All the bacterial strains can tolerate 3 % salt concentration, and capable to survive at the highest 45 °C temperature and pH 11 (without isolate 1). Three preeminent bacteria, Agrobacterium tumefaciens (B1), Bacillus subtilis (B2), and Lysinibacillus fusiformis (B3) were specified through morpho-biochemical and molecular (16S rRNA gene sequence) exploration for inoculation. To assess the plant growth-promoting activities, germination tests are applied where bacterial inoculation increased germination in saline and non-saline conditions. Control group (C) showed 89.47 % and bacterial treated groups (C + B1, C + B2, and C + B3) 95 %, 90 %, and 75 % germination after 2 days of inoculation. In (1 % NaCl) saline condition control group revealed 40 % whereas three groups with bacteria showed 60 %, 40 %, and 70 % germination after 3 days, which increased 70 %, 90 %, 85 %, and 95 % respectively after 4 days of inoculation. The HPGPR significantly improved plant development metrics such as root length, shoot length, fresh and arid biomass yield, chlorophyll content, etc. Our results suggest that the salt-resistant bacteria (Halotolerant) have a great potential role in recuperating plant growth and would be cost-effective as a bio-inoculant in saline conditions to be used as a prospective bio-fertilizer for rice production. These findings indicate that the HPGPR has a substantially promising function in reviving plant development in an eco-friendly manner.
位于根际周围的无毒耐盐促植物生长根际细菌（HPGPR）可以减轻非生物胁迫（如盐分和干旱），提高作物产量。盐分对在沿海地区种植农产品（如水稻）构成了重大挑战。由于耕地有限和人口增长率高，提高产量至关重要。本研究旨在从豆科植物根瘤中鉴定HPGPR，并评估它们对孟加拉国沿海地区遭受盐胁迫的水稻植株的影响。基于培养形态、生化、盐分、pH值和温度耐受性特征，从豆科植物（菜豆、长豇豆、柽麻和含羞草）的根瘤中分离出16株细菌。所有菌株都能耐受3%的盐浓度，并且能够在最高45°C的温度和pH值11的条件下存活（分离株1除外）。通过形态生化和分子（16S rRNA基因序列）探索确定了三株优势细菌，即根癌农杆菌（B1）、枯草芽孢杆菌（B2）和梭形赖氨酸芽孢杆菌（B3）用于接种。为了评估植物促生长活性，进行了发芽试验，结果表明细菌接种提高了在盐渍和非盐渍条件下的发芽率。接种2天后，对照组（C）的发芽率为89.47%，细菌处理组（C + B1、C + B2和C + B3）的发芽率分别为95%、90%和75%。在（1% NaCl）盐渍条件下，对照组3天后的发芽率为40%，而三组细菌处理组的发芽率分别为60%、40%和70%，接种4天后分别提高到70%、90%、85%和95%。HPGPR显著改善了植物发育指标，如根长、茎长、鲜重和干重产量、叶绿素含量等。我们的结果表明，耐盐细菌在恢复植物生长方面具有巨大的潜在作用，并且作为盐渍条件下的生物接种剂将具有成本效益，有望用作水稻生产的生物肥料。这些发现表明，HPGPR在以生态友好方式恢复植物发育方面具有非常有前景的作用。
