Caracterización y función biológica de las comunidades bacterianas en el intestino de Nezar viridula

MEDINA, V; SARDOY, P; PAGANO, E; ZAVALA, J. A.

Buenos Aires

Jornada; III jornada del INBA; 2013

INBA

ABSTRACT Southern green stinkbug (Nezara viridula) is one of the most relevant pests of soybean crops, which feeds on developing seeds in spite of their strong defenses against herbivory. We propose that the microbial community in the gut of stinkbugs have a role in helping digestion and tolerance to chemical defenses of soybeans, such as cysteine protease inhibitors (CysPI). The aim of this study was to determine the effects of gut bacteria effects on CysPI activity and isoflvanoids, to potent chemical defenses against herbivores. Stinkbugs were collected from soy fields, dissected and guts were removed in sterility. Cell counts and isolations, and 16S ribosomal sequencing were performed. Enterococcus faecalis, Enterobacter sp, Pantoea sp, Klebsiella oxytoca, strains with cell counts of 104-106 UFC/mg gut were identified. Also a non culturable N. viridula symbiont was identified in all samples. Pure cultures were use for soybean flour fermentation. Although no effect on isoflavonoids degradation was observed, all strains assayed diminished inhibitory activity of soybean flour CysPIs. Inhibitory activity of CysPI´s decreased 77% when soy flour was fermented with E. faecalis strain. Protein solubility also decreased 45% due to acid production during fermentation. Our results suggest that gut bacteria helps maintaining low pH for an optimal activity of insect cisteine proteases and may inactivate CysPI´s.