Metabolite-Mediated Antioxidant-Rich Bacterial Isolates for the Control of Anthracnose Disease and Enhancement of the Post-Harvest Shelf Life of Mango (Mangifera indica L.)

Mango (Mangifera indica L.), being a climacteric fruit, is highly perishable due to rapid ripening and post-harvest diseases like anthracnose, which significantly shorten its shelf life and limit long-distance sea export. To mitigate these constraints, a chemical-free secondary metabolite-based formulation (SMsF) was developed to delay ripening and control post-harvest anthracnose during storage. The SMsF possesses dual-action properties and is derived from the culture filtrate of Priestia aryabhattai, exhibiting ACC deaminase activity that restricts ethylene formation. It is also rich in antifungal compounds such as vanillic acid, hydroxybenzoic acid, cryptochlorogenic acid, palmitic acid, and BBIT, which inhibit anthracnose development. Additionally, it contains antioxidants including quercetin, coumaryl quinic acid, oleic acid, and acetylglycitin that enhance shelf life and disease resistance. The efficacy of SMsF was evaluated in mango cv. Banganapalli was stored at 12 ± 1 °C and 85–90% relative humidity under simulated reefer conditions (SRC). Integration of gamma irradiation with SMsF provided superior results in disease control and shelf-life extension. The combined treatment maintained higher fruit firmness (0.86 kg cm−2), optimal total soluble solids (14.3 °B), desirable acidity (0.22%), and complete suppression of anthracnose (PDI = 0) up to 40 days of storage under SRC compared with the control. The findings conclusively demonstrate that the synergistic application of SMsF and gamma irradiation effectively regulates ripening, enhances fruit quality, and ensures complete disease suppression, thereby significantly extending storage life. This approach holds strong scientific and commercial significance as a sustainable, residue-free, and export-oriented technology capable of improving long-distance transportation, reducing post-harvest losses, and promoting safe mango trade.