Bioprospecting the biocontrol, abiotic stress tolerance and plant growth-promoting attributes of three Aspergillus species isolated from Peperomia pellucida (L.) Kunth

Synthetic agrochemicals have long been used to enhance plant productivity and combat food insecurity. However, due to their poor environmental and safety records, eco-friendly and sustainable strategies, such as the use of endophytic fungi, are seen as viable alternatives. Thus, this study aimed to investigate the plant growth-promoting traits, extracellular enzyme production capacity, abiotic stress tolerance, and biocontrol potential of endophytic fungi associated with Peperomia pellucida leaves. The isolates were identified as Aspergillus flavus (PPLF-1), A. niger (PPLF-4), and A. flavus (PPLF-5) using molecular tools. All isolates produced amylase, lipase, protease, cellulase, and pectinase, whereas only PPLF-4 showed potential for laccase production. The three isolates could solubilise inorganic phosphate, produce HCN, ammonia and siderophores; however, only PPLF-1 produced indole-3-acetic acid. Overall, the isolates tolerated up to 18% NaCl. For chromium and cadmium stress, PPLF-4 showed the highest tolerance, and no isolate survived beyond 150 ppm of cadmium. All isolates demonstrated differential antagonism against selected phytopathogens ( Rhizoctonia solani, Botrytis cinerea , and A. niger ), with PPLF-5 exhibiting the greatest inhibitory potential. Polyketide synthase-I (PKS-I) genes were detected in PPLF-1 and PPLF-4, while non-ribosomal protein synthase (NRPS) genes were detected only in PPLF-5. Our results showed that the three Aspergillus species may be a promising source of agricultural biologicals.