Abstract
Milk processing lines offer a wide variety of microenvironments where a diversity of microorganisms can proliferate. We sampled crevices and junctions where, due to deficient reach by typical sanitizing procedures, bacteria can survive and establish biofilms. The sampling sites were the holding cell, cold storage tank, pasteurizer and storage tank - transfer pump junction. The culturable bacteria that were isolated after the sanitation procedure were predominantly Pseudomonas spp., Serratia spp, Staphylococcus sciuri and Stenotrophomonas maltophilia. We assayed several phenotypic characteristics such as the ability to secrete enzymes and siderophores, as well as the capacity of the strains to form biofilms that might contribute to their survival in a mixed species environment. The Pseudomonas spp. isolates were found to either produce proteases or lecithinases at high levels. Interestingly, protease production showed an inverse correlation with siderophore production. Furthermore, all of the Serratia spp. isolates were strong biofilm formers and spoilage enzymes producers. The organisms identified were not mere contaminants, but also producers of proteins with the potential to lower the quality and shelf-life of milk. In addition, we found that a considerable number of the Serratia and Pseudomonas spp. isolated from the pasteurizer were capable of secreting compounds with antimicrobial properties.
Highlights
One of the most challenging tasks in any industrial food processing line is the upkeep of sanitary conditions as the high availability of nutrients and oxygen favour microbial growth
The culturable isolates recovered from the crevices of cleaned devices from a milk processing plant (Fig. 1) and identified by 16S rDNA included five prevalent groups of bacteria in total: Pseudomonas spp. (37%); Staphylococcus (20%); Serratia spp. (16%), Stenotrophomonas sp. (15%), and Alcaligenes (5%)
The sample originating in the pasteurizer predominantly contained Pseudomonas spp. and Serratia spp., whereas the junction was mainly dominated by Pseudomonas spp., Staphylococcus spp. and Stenotrophomonas sp. isolates
Summary
One of the most challenging tasks in any industrial food processing line is the upkeep of sanitary conditions as the high availability of nutrients and oxygen favour microbial growth. Residues inherent to the processing of food accumulate in these locations and provide a setting prone to colonization by bacteria, especially in the form of biofilms. Bacteria in biofilms are more resistant to the action of sanitizing agents than are their planktonic counterparts [1,2]. This increased resistance is likely multifaceted, arising from inherent differences in the physiological states of bacteria within the biofilm as well as from the protective nature of the matrix. Even bacteria not usually capable of adhering to a surface and secreting matrix can persist within the biofilm community by adhering to the matrix produced by others. In addition to allowing bacteria to persist, biofilm communities contribute to the corrosion of surfaces and piping [6,7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
