Evaluation of cleaning process in a chicken meat industry facilities by the identification of Listeria monocytogenes, Salmonella sp., and microbiome analysis

Abstract

Sanitation procedures performed in food industries can interfere with the hygienic-sanitary quality of products. The objective of this study was to evaluate the operational and pre-operational cleaning process of a chicken slaughterhouse through the detection of Listeria monocytogenes, Salmonella sp. and microbiome analysis. Surface samples of equipment and utensils were collected before (n=160) and after (n=160) industrial cleaning processing to count aerobic mesophiles (ISO 4833-1), enterobacteria (ISO 21528-2), Pseudomonas sp. (ISO 13720), and to seek the presence of L. monocytogenes (ISO 11.290-1) and Salmonella sp. (ISO 6579). From the collected samples, 12.5% (n=40) were submitted to 16S RNA gene sequencing to assess microbial ecology. The cleaning process reduced 53% of mesophilic aerobic counts, 97% of enterobacteria, 94% of Pseudomonas sp. and eliminated Salmonella sp., however, was ineffective for L. monocytogenes. The presence of 133 genera was identified before processing, being Pseudomonas sp. (45.4%), Acinetobacter sp. (16.6%) and Aeromonas sp. (5.4%) the main ones. Of the 313 species identified, Pseudomonas fluorescens (22.9%), Acinetobacter johnsonii (13.8%), P. putida (6.2%) and Aeromonas salmonicida (3.1%) were the predominant ones. After cleaning processing, 63 genera were observed, composed by Aneurinibacillus sp. (19.5%), Pseudomonas sp. (12.8%), Acinetobacter sp. (11.3%), Anoxybacillus sp. (7.7%) and Enterococcus sp. (6.7%). Among the 123 species, the most identified ones were Aneurinibacillus aneurinilyticus (16.9%), P. fluorescens (7.7%), Anoxybacillus flavithermus (7.1%), Enterococcus cecorum (6.2%) and Escherichia coli (3.8%). Among the identified genera and species, the microorganisms were divided in three groups, one composed of microorganisms related to the processing of the products (Aneurinibacillus sp., Anoxybacillus sp. and Enterococcus sp.), the second identified after cleaning (Stenotrophomonas sp., Magnetospirillum sp. and Citrobacter sp.) and the last one by microorganisms that inhabited both steps (Pseudomonas sp., Acinetobacter sp. and Aeromonas sp.). The results of the study demonstrate a considerable reduction of indicator microorganisms and Salmonella sp. after the cleaning process, except with L. monocytogenes. Beside the cleaning process, some bacteria as Pseudomonas sp., Acinetobacter sp. and Aeromonas sp. remained on the analyzed surfaces, being tolerant and capable of originating biofilms.