Data_Sheet_1_Heavy Metal–Resistant Plant Growth–Promoting Citrobacter werkmanii Strain WWN1 and Enterobacter cloacae Strain JWM6 Enhance Wheat (Triticum aestivum L.) Growth by Modulating Physiological Attributes and Some Key Antioxidants Under Multi-Metal Stress.xlsx

Due to wastewater irrigation, heavy metal (HM) exposure of agricultural soils is a major limiting factor for crop productivity. Plant growth–promoting bacteria (PGPB) may lower the risk of HM toxicity and increase crop yield. In this context, we evaluated two HM-resistant PGPB strains, i.e., Citrobacter werkmanii strain WWN1 and Enterobacter cloacae strain JWM6 isolated from wastewater-irrigated agricultural soils, for their efficacy to mitigate HM (Cd, Ni, and Pb) stress in a pot experiment. Increasing concentrations (0, 50, 100, and 200 ppm) of each HM were used to challenge wheat plants. Heavy metal stress negatively affected wheat growth, biomass, and physiology. The plants under elevated HM concentration accumulated significantly higher amounts of heavy metals (HMs) in shoots and roots, resulting in increased oxidative stress, which was evident from increased malondialdehyde (MDA) content in roots and shoots. Moreover, alterations in antioxidants like superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), and catalase (CAT) were observed in plants under HM stress. The severity of damage was more pronounced with rising HM concentration. However, inoculating wheat with Citrobacter werkmanii strain WWN1 and Enterobacter cloacae strain JWM6 (107 CFU ml–1) improved plant shoot length (11–42%), root length (19–125%), fresh weight (41–143%), dry weight (65–179%), and chlorophyll a (14%-24%) and chlorophyll b content (2–24%) under HM stress. Citrobacter werkmanii strain WWN1 and Enterobacter cloacae strain JWM6 either alone or in co-inoculation enhanced the antioxidant enzyme activity, which may lower oxidative stress in plants. However, seeds treated with the bacterial consortium showed an overall better outcome in altering oxidative stress and decreasing HM accumulation in wheat shoot and root tissues. Fourier transform infrared spectroscopy indicated the changes induced by HMs in functional groups on the biomass surface that display effective removal of HMs from aqueous medium using PGPB. Thus, the studied bacterial strains may have adequate fertilization and remediation potential for wheat cultivated in wastewater-irrigated soils. However, molecular investigation of mechanisms adopted by these bacteria to alleviate HM stress in wheat is required to be conducted.

鉴于废水灌溉导致的农业土壤重金属（HM）污染，已成为制约农作物产量的重要限制因素。植物生长促进菌（PGPB）能够降低HM毒性风险并提升作物产量。在此背景下，本研究评估了从废水灌溉的农业土壤中分离得到的两种HM抗性PGPB菌株，即克雷伯菌属 werkmanii 菌株 WWN1 和肠杆菌属 cloacae 菌株 JWM6，在盆栽实验中针对HM（镉、镍和铅）胁迫的缓解效果。通过使用不同浓度的HM（0、50、100和200 ppm）对小麦植物进行挑战。重金属胁迫对小麦的生长、生物量和生理状况产生了负面影响。在高浓度HM条件下，植物在茎和根中积累的重金属（HM）显著增加，导致氧化应激加剧，这在根和茎中丙二醛（MDA）含量的增加上得以体现。此外，在HM胁迫条件下，植物中抗氧化酶如超氧化物歧化酶（SOD）、过氧化物酶（POD）、抗坏血酸过氧化物酶（APX）和过氧化氢酶（CAT）发生了改变。随着HM浓度的升高，损害程度愈发严重。然而，将小麦接种克雷伯菌属 werkmanii 菌株 WWN1 和肠杆菌属 cloacae 菌株 JWM6（107 CFU ml–1）后，在HM胁迫条件下，植物的茎长（11–42%）、根长（19–125%）、鲜重（41–143%）、干重（65–179%）以及叶绿素a（14%-24%）和叶绿素b含量（2–24%）均得到显著改善。克雷伯菌属 werkmanii 菌株 WWN1 和肠杆菌属 cloacae 菌株 JWM6单独或联合接种均能增强抗氧化酶的活性，这可能有助于降低植物的氧化应激。然而，经细菌群落处理的种子在改变氧化应激和减少小麦茎和根组织中HM积累方面表现出更佳的整体效果。傅里叶变换红外光谱表明，HM对生物量表面功能团的影响，并揭示了利用PGPB从水相介质中有效去除HM的机制。因此，所研究的细菌菌株可能具备足够的肥力和修复潜力，适用于在废水灌溉土壤中种植的小麦。然而，为了深入了解这些细菌缓解小麦HM胁迫的机制，有必要进行分子层面的研究。