Enterococcus spp. Survival through the use of standard protocol for clostridium sp. isolation

Abstract

The genera Clostridium and Enterococcus are very different from each other, both morphologically and physiologically. Due to the high resistance by the sporulation capacity of Clostridium species, the thermal shock is a characteristic tool used for the isolation and identification of these microorganisms, this way, it would eliminate any other bacteria that did not present spores. The objective of this work is to show that Enterococcus sp. resist the temperature treatment and grow in culture media used for the isolation of Clostridium sp. For this, the present study initially attempted to identify reducing sulfite clostridia in poultry products, through the use of specific culture media and heat shock treatment. However, the PCR did not detect the presence of Clostridium sp. Then, sequencing of the 16S rDNA region was performed, which showed that the reducing sulfite colonies that were being isolated were, actually, Enterococcus spp. With this, some tests were carried out using different temperature and time combinations in the thermal shock, as well as the use of five different selective and differential culture media, in an attempt to eliminate any contaminants, but all without success, because these bacteria resisted to all modification. Therefore, the standard protocol for the isolation of bacteria of the genus Clostridium does not eliminate Enterococcus, which can lead to failures in the quantification and qualification of sulfite reducing microorganisms, a fact that can significantly affect food safety and animal health.