Assessing the potential of chitosan based coatings in modulation of bacteriome on tomato carposphere

Abstract

Chitosan based edible fruit coatings are being considered today as an unconventional, ecofriendly and safe alternative of postharvest chemical treatments. The mechanism of action of chitosan coatings, like its antifungal nature or forming a barrier for transpiration and respiration, is already known. We intended to study the effect of the chitosan on natural carposphere microbiome, specifically on non-culturalable bacterial communities during storage to explore the prebiotic like nature of the chitosan based coatings. Hence the effect of coatings viz. CS (1% Chitosan), TL (Tulsi or Ocimum sanctum leaf, 1 g L-1 aqueous extract), and CS/TL mixed (2:1, 1% Chitosan and Tulsi leaf extract) was observed on coated tomato fruit. Metagenomic bacteriome analyses revealed that the untreated samples were comparatively rich epiphytic bacterial flora though the core microbiome was conserved in all the samples. Bacterial community in ripened tomato fruit (after 7 d) was mostly dominated by Acetobacter (49%) while on treatment of coatings genera like Lactobacillus, Weissella, Methylovoruse, Bacillus and Pseudomonas increased. These bacteria can act as potential bio agents in carposphere while the probiotic nature of genera as Lactobacillus or Weissella can also help in delaying the ripening of fruit. As this was a pilot study, more such studies are needed on microbial communities associated with fruits, their assembly and dynamics as well as the nature of their contribution to fruit quality and pathogen resistance during fruit ripening and storage.