Aislamiento e identificación de Bacillus cereus a partir de dos variantes de arroz comercial (Oryza sativa L.)

Abstract

Bacillus cereus is a common soil bacterium with importance for public health and Biotechnology. With the
aim to isolate strains of this bacterium for afterward studies, and to evaluate their permanence in cooked rice, the Kramer
et al. (1982) protocol was used. In this sense, samples of rice grains with shell and cooked rice were collected and bacteria
with hemolytic and positive lecitinase properties were looked. Identification of the isolates was carried out by means of
morphological and biochemical tests. Fourteen isolates were obtained, with eight of these combining distinctive characteristics
of B. cereus as compared with B. cereus ATCC 11778, including antibiotics resistance. Presence of parasporal
bodies, typical of B. thuringiensis, was not observed. It was verified that hemolytic and lecitinase positive bacteria can
be isolated from the cooked rice eight hours after the cooking, increasing the number of isolated if this is conserved to
ambient temperature, which transform this food in potentially dangerous for consume. These results suggest moreover
the possibility to use the commercial rice as source to B. cereus isolating