Toward elucidate strategies of paddy diazotrophic cyanobacteria in cope with soil acidity stress: physiological and metabolic analyses

ABSTRACT:

Diazotrophic cyanobacteria have a pivotal role in nitrogen fixation and soil fertility in paddy ecosystems, yet their responses to soil acidity stress (SAS) remain elusive. This study investigated the physiological and metabolic mechanisms underlying acid tolerance in diazotrophic cyanobacteria by comparing an acid-resistant strain (Nostoc sp. AT-23S) and an acid-sensitive strain (Nostoc sp. AS-61S) under acidic (pH 4.68) and neutral (pH 7.0) soil conditions. The results demonstrated that AT-23S maintained cytoplasmic pH homeostasis, sustained high levels of photosynthetic efficiency and nitrogenase activity, and exhibited enhanced synthesis of tightly bound extracellular polysaccharides (TB-EPS) under acid stress. Metabolomic analysis revealed significant up-regulation of gamma-aminobutyric acid (GABA) and 1-pyrroline-5-carboxylic acid (P5C) in AT-23S under acid stress; in contrast, AS-61S failed to maintain pH homeostasis, showed severe oxidative stress, and down-regulated GABA and P5C synthesis. The GABA was primarily originated from the putrescine degradation pathway, as confirmed by elevated diamine oxidase (DAO) activity and putrescine utilization rate. These findings demonstrate that the accumulation of GABA and P5C may be critical adaptive mechanism for acid tolerance in diazotrophic cyanobacteria, providing novel insights into their survival in acidic paddy soils.

INSTRUMENT(S): Liquid Chromatography MS - negative - reverse-phase, Liquid Chromatography MS - positive - reverse-phase

PROVIDER: MTBLS13358 | MetaboLights | 2025-11-20

REPOSITORIES: MetaboLights