Protective role of epiphytic fluorescent Pseudomonas on natural postharvest decay of tomato at room temperature

Abstract

Following harvest, tomato fruits are susceptible to attack by many fungal pathogens, but  healthy fruits may also  harbor beneficial microflora, which can delayed the spoilage  of fruit. In this study, 30 isolates of epiphytic fluorescent Pseudomonas  were isolated from healthy fruits of lemon, melon, grapefruit, tomato and orange. Twelve isolates were identified on molecular basis by amplifying 16S rDNA using a genus-specific primer set PA-GS-F 5’-GACGGGTGAGTAATGCCTA-3’ and PA-GS-R F 5’-CACTGGTGTTCCTTCCTATA-3’ on a conserved sequence of the genus Pseudomonas with a product size ~618 bp. Three potential isolates were examined for their ability to  delayed the  postharvest natural  spoilage and maintained the physiochemical properties during storage for fifteen days in season 2013 and 2014. All three isolates showed promising control of postharvest diseases of tomato in comparison with control in both seasons up to fifteen days of storage at room temperature (23±4 oC, Rh 25-70%). The epiphytic bacterial isolates has delayed the fruit weight loss and maintained  fruit firmness, total solids, pH and titratable acidity. Isolates also slowed the accumulation of lycopene indicating their potential in controlling the major changes in physiochemical properties. In both season Pseudomonas treated tomatoes showed no or negligible infestation of common postharvest fungi and bacteria as compared to control and positive control (1% K-sorbate).