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Are biological control agents, isolated from tropical fruits, harmless to potential consumers?

Author:
Ocampo-Suarez, Iris Betsabee, López, Zaira, Calderón-Santoyo, Montserrat, Ragazzo-Sánchez, Juan Arturo, Knauth, Peter
Source:
Food and chemical toxicology 2017
ISSN:
0278-6915
Subject:
Bacillus subtilis, Candida saitoana, Cryptococcus laurentii, Debaryomyces hansenii, Meyerozyma guilliermondii, bacteria, biochemical pathways, biodegradability, biological control agents, cytotoxicity, developing countries, fruits, humans, lysosomes, membrane permeability, necrosis, plant pathogens, pollution, postharvest losses, reports, sustainable agriculture, toxicology, tropical and subtropical fruits, vegetables, yeasts
Abstract:
Postharvest losses of fruits and vegetables can reach up to 25% in developed and up to 50% in developing countries. (Sub)tropical fruits are especially susceptible because their protecting peel can easily be damaged. Traditionally used pesticides are associated to environmental pollution and possible harmful health effects. An alternative are biocontrol agents (BCA), means bacteria or yeasts applied onto the fruits to inhibit the growth of phytopathogens. Many reports on their effectiveness have been published, however, reports on their harmlessness to consumers are still rare. Culture extracts of six BCAs, tested on two human lines (Caco-2, HeLa), exhibited no cytotoxic effect, when used directly (1×) to protect the fruits; however, when they are 5×overconcentrated, the confluence of proliferating cells was reduced, but not of differentiated Caco-2. In both cases necrosis was not increased. On proliferating cells, the 5×-extract from Cryptococcus laurentii or Debaryomyces hansenii reduced lysosome functionality and the 6.25×extract from Meyerozyma guilliermondii or Candida famata increased membrane permeability, while only the 25×-extract from M. guilliermondii or M. caribbica reduced slightly the metabolic activity. The extract of Bacillus subtilis showed no cytotoxic effect up to 10× concentration. Overall, their low cytotoxicity combined with high biodegradability make these products suitable for sustainable agriculture.