Postharvest losses in fruits and vegetables, estimated at 20–50% globally, undermine food security and economic stability. Biological control agents (BCAs), including bacteria, yeasts, and fungi, are emerging as eco-friendly alternatives to synthetic fungicides. This review comprehensively analyzes advances in BCAs for postharvest disease control and highlights their mechanisms, impacts on produce quality, and integration into sustainable systems. Additionally, this review delves into the innovative role of nanotechnology-enhanced BCAs (Nano-BCAs), emphasizing nanoencapsulation, improved biofilm formation, targeted delivery, and antimicrobial synergy. While promising, Nano-BCA application requires risk assessment, regulatory clarity, and cost-effective scalability. This synthesis aims to guide future research and application toward sustainable, safe, and efficient postharvest disease management.

Soft rot disease caused by Pectobacterium carotovorum is a major postharvest problem in fruits and vegetables, particularly in East Asia. This systematic review and meta-analysis aimed to collate and critically evaluate studies on the biocontrol efficacy of microbial antagonists against P. carotovorum in East Asia, quantitatively estimate their effectiveness, and identify research gaps. A systematic search of PubMed, Web of Science, and Scopus databases was conducted following PRISMA guidelines and yielded 14 eligible studies (21 datasets) from East Asia. The overall pooled estimate of the relative reduction in disease incidence by microbial antagonists was 82% (95% CI: 74–88%; I² = 88.2%), indicating high but highly variable biocontrol efficacy across studies. Subgroup analyses revealed varying efficacy among different antagonists, with Chitosan-enhanced Lactobacillus pentosus and Leuconostoc fallax showing the highest potential (100% reduction), followed by Pseudomonas aeruginosa (90%), Bacillus velezensis (85.7%), and Lactobacillus paracasei WX322 (82.2%). Meta-regression identified BCA cell concentration, sample size, storage days, and storage temperature as significant sources of heterogeneity. Most studies were conducted in China, highlighting the need for more research in other East Asian countries. Microbial antagonists demonstrate substantial potential for reducing soft rot incidence, yet the high heterogeneity across studies warrants cautious interpretation of the pooled effect. While these findings are promising, further field validation and expanded geographical representation are needed.

Blue mold decay caused by Penicillium expansum is a major disease of table grapes, causing substantial economic losses. With increasing environmental concern and consumer interest in chemical-free products, eco-friendly biocontrol strategies are necessary. The strains of Wickerhamomyces anomalus incubated with chitosan (WaC) and Bacillus subtilis (Bs) are already reported for their promising efficiency to control blue mold disease caused by P. expansum. However, their individual application is less effective compared to chemical fungicides. The current study determined combined application of these two prominent antagonistic microbes against blue mold decay of grapes. Initially we carried out a compatibility study which confirmed that there was no mutual inhibition among the strains, enabling synergistic formulations. An in vitro study showed that the combined application of WaC and Bs better reduces P. expansum colony diameters at a 4:1 ratio. This ratio also maximally suppressed the pathogen spore germination (62% reduction) and germ tube elongation (67% reduction). The in vivo studies also showed that WaC + Bs (at 4:1) significantly minimized lesion diameters and decay rates of grapes during the 13-day storage, outperforming individual applications. The physicochemical quality parameters of table grapes were also better preserved. The treatments modulated antioxidant and defense enzymatic activities such as PPO, POD, PAL, APX, SOD, and CHI. The elevated phenolic and flavonoid contents, with strong positive correlations among the enzymes, underscored the induced resistance of the host. These findings highlight the synergistic potential of chitosan-enhanced Wa with Bs for effective, sustainable postharvest biocontrol, extending grape shelf life and reducing chemical reliance.