This study analyzed biofilms composed of Escherichia coli and Staphylococcus aureus on a stainless steel surface, in the presence of food residues (milk and meat exudate), at 25 and 35 °C, with the objective of simulating the real conditions of industrial processing of these foods. The biofilm formed on the surface was determined by quantifying the colonies and scanning electron microscopy. In addition to milk and meat exudate, three different culture media were used, one specific for each bacterium and a common environment for the growth of both bacteria (Mueller Hinton agar, MH). Such conditions were favorable for the biofilm formation of both bacteria, with predominance of the Gram‐negative species in the multispecies biofilm. The food residues favored the formation of the biofilm in both temperatures, especially the meat exudate at 35 °C, when compared to the MH broth. Therefore, substrate and temperature directly influenced the microbial composition of the biofilm.
Practical applications
This study demonstrates the influence of industrial residue (substrate) on temperature in the composition of a biofilm. As it was evaluated two distinct bacteria, one Gram‐positive and another Gram‐negative, that can be present in several industrial food processing, it can be observed that the substrate and the temperature may favor the development of a species. This fact is extremely relevant so that a correct hygiene process can be applied and it is necessary to know the composition of the biofilm on a certain surface to combat it more effectively.
Chemical products traditionally used in the disinfection of water bodies often pose human health risks. For this reason, studies on natural coagulants such as Moringa oleifera Lam. represent an alternative for the inactivation of pathogenic microorganisms, among which is Escherichia coli. This study evaluated the effect of different concentrations of coagulants obtained from Moringa seed extracts and their protein fractions in the inactivation of E. coli during the coagulation/flocculation process. The coagulants studied were the aqueous extract, saline extract and protein fractions albumin and globulin, highlighting that the protein fractions were more effective on inactivating E. coli. The protein fraction globulin at a concentration of 10.0 mg L−1 showed bactericidal effects against E. coli within 18 min, whereas the albumin showed a bacteriostatic effect within 48 min because it isolated colonies in the sediment sample.
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