Multifunctional paddy cultivated soil-borne bacteria: potential biofertilizer

Biofertilizers have gained attention as eco-friendly alternatives to mitigate the adverse effects of chemical fertilizers. This study focuses on recycling paddy straw waste using lignocellulolytic soil-borne bacteria isolated from paddy fields in Kırklareli and Samsun, Türkiye. This approach supports soil organic matter enrichment and reduces chemical fertilizer dependence, thus lowering greenhouse gas emissions. Microorganisms were isolated using selective media. Cellulolytic and ligninolytic activities were assessed via DNS and Azure-B methods, respectively. Among the isolates, Bacillus sp. S2 (Samsun) exhibited the highest enzymatic activities and grew on nitrogen-free Jensen's medium, suggesting potential nitrogen-fixing ability. Pseudomonas sp. K2 (Kırklareli) showed moderate but consistent lignocellulolytic activity. Following 30 days of incubation with powdered paddy straw, gas chromatography-mass spectrometry (GC-MS) analysis revealed that S2 produced the highest levels of 4-coumaric acid (2.371%), benzoic acid (3.019%), and formic acid (1.280%), along with xylitol (1.390%) and 1-triacontanol (1.298%)-compounds with agronomic relevance for plant growth, stress tolerance, and soil health. K2 uniquely produced arabitol, associated with osmoprotection. BLAST analysis showed that S2 shares 98% identity with Bacillus velezensis and B. amyloliquefaciens, while K2 showed 95% similarity to Ectopseudomonas chengduensis, E. alcaliphila, and P. sihuiensis. These traits support their potential use in sustainable agriculture and crop residue management.