Biological Control of Postharvest Spoilage in Fresh Mandarins (Citrus Reticulata Blanco) Fruits Using Bacteria During Storage

Citrus fruit can be infected by many fungal pathogens, and these pathogens cause considerable losses during storage and transportation. Recently, biological control methods of postharvest diseases are getting more prevalent due to the effects of chemical residues on fruits. The present study was carried out to determine the antifungal activities of atotal of four candidate biocontrol bacterial strains (Bacillus subtilis TV-6F, B.subtilis TV-17C, Pseudomonas flourescens RK-1105 and Agrobacterium rubi RK-33) against some pathogenic fungi (Alternaria alternata, Sclerotinia sclerotiorum, Pythium ultimum, Penicillium digitatum and P.italicum) on Petri plate assays. They were also tested to evaluate the potential application of the bacteria to bio-control postharvest decay on mandarin fruits during storage. In addition, they were tested to investigate the enzyme activities of the bacteria. The results of the present study showed that all non-pathogenic bacterial strains showed less or more antifungal activity against the tested pathogens on Petri plate assays. They were also significantly reduced disease severity on mandarin fruits during storage. Chitinase, glucanase and protease enzyme activities of the bacteria were positive except A.rubi RK-33. B.subtilis TV-17C and A.rubi RK-33 strains were the most effective bacteria. In controlling postharvest decay of mandarin fruit, these bacterial strains can be used as new bio-control agents. Hence, further study is necessary to develop along-term carrier material, to complete cytotoxicity using human cell, ecotoxicity and toxicity tests of these bacterial strains on target organisms.