Screening of a multifunctional acid-tolerant PGPR strain and its efficacy in biocontrol and amelioration of continuous cropping obstacles.

Soil acidification and continuous cropping obstacles (CCO) are significant agricultural challenges that threaten crop yield and soil health. Traditional microbial interventions often lack multifunctionality and ecological adaptability, limiting their effectiveness in acidic soil environments. This study aimed to address these challenges by isolating and evaluating multifunctional microorganisms capable of ameliorating soil acidity and suppressing soil-borne diseases. We successfully screened acid-tolerant, alkali-producing bacteria from acidic forest soils and identified strain JL-77 as Paraburkholderia fungorum. This strain demonstrated robust acid tolerance, attributed to its alkali-generating ability which significantly increased soil pH from 5.13 to 5.46 in incubation experiments. Mechanistic studies revealed that JL-77 possesses multiple plant growth-promoting traits, including nitrogen fixation, phosphate solubilization, IAA production, ACC deaminase activity, and the degradation of autotoxins such as benzoic and p-hydroxybenzoic acid. Furthermore, JL-77 successfully colonized the rhizosphere and exhibited strong biocontrol effects against Fusarium oxysporum, F. solani, and Phytophthora cactorum, significantly reducing the disease index in continuous cropping soil. In trials with Atractylodes macrocephala and pak choi, JL-77 application effectively mitigated continuous cropping obstacles and enhanced plant biomass and quality. These findings suggest that JL-77 is a highly effective multifunctional microorganism with potential applications in improving acidic soils, managing soil-borne diseases, and promoting sustainable agricultural practices.