No abstract

The aim of the research was to study the features of formation of dairy equipment microflora, the ability of microorganisms to form biofilms on the noncorrosive steel surface with the different roughness and to determine the effectiveness of disinfectants. It was established, that bacteria of Bacillus, Lactobacillus genera of Enterobacteriaceae family are most often extracted from the dairy equipment after the sanitary processing by modern disinfectors, in less number of cases – staphylococci, enterococci, streptococci and pseudomonades. Extracted bacteria form mainly biofilms of the high and middle density. In 100 % of cases biofilms of the high density were formed by Bacillus spp. and Enterococcus faecalis bacteria. It indicates the fact that at the disinfection of the dairy equipment, only stable bacteria that have the ability to produce a biofilm of the high density, remain on its surface. It was established, that the dairy equipment surface relief, namely roughness, has an influence on the process of biofilm formation in Escherichia coli. On the noncorrosive steel surface with the roughness 0,16±0,065 mcm Escherichia coli form biofilms of the lower density comparing with the surface with the density 0,63–0,072 mcm during 24 hours at the temperature 17 °С. It was established, that working solutions of disinfectants P3-ansep CIP, Eco chlor, Medicarine and Maxidez were more effective as to plankton bacteria. Microorganisms, formed in biofilms, turned out stable to these disinfectants. Most effective disinfectant for the influence on bacteria on biofilms is Р3-oxonia active – 150. So, the obtained data indicate that for the effective sanitary processing of the dairy equipment it is necessary to use disinfectants that influence bacteria in biofilms.

Наведено дослідження процесу адгезії бактерій до поверхні з різною шорсткістю залежно від розмірів і форми. Встановлено, що на поверхні нержавіючої сталі з шорсткістю 2,687±0,014 мкм, процес плівкоутворення у E. coli та S. aureus проходив однаково упродовж з 3 до 24 години та не залежав від розмірів бактерій. Це дозволяє стверджувати, що паличковидні і кокові бактерії вільно прикріпляються у западинах шорсткості та розпочинається початковий процес першої стадії формування біоплівки. Під час санітарної обробки у западинах шорсткості можуть залишатися, як кокові, так паличковидні бактерії. На поверхні сталі з шорсткістю 0,95±0,092 мкм процес плівкоутворення у S. aureus проходив інтенсивніше, ніж у E. coli. Упродовж 3 год інкубації щільність сформованих біоплівок S. aureus була в 1,2 раза більша, порівняно з біоплівками E. coli. У наступні 15 годин інкубації сформовані біоплівки S. aureus були, в середньому в 1,3 раза щільніші. Це дає підставу вважати, що S. aureus завдяки кулястій формі здатний розміщуватися у западинах шорсткості 0,95±0,092 мкм і швидше адгезуватися до поверхні. Водночас E. coli, завдяки паличковидній формі, за такої шорсткості поверхні може адгезуватися у западини тільки повздовж. Доведено, що за шорсткості поверхні 0,63±0,087 мкм інтенсивність плівкоутворення S.aureus була, в середньому в 1,4 раза швидша, ніж у E. coli. Водночас, за шорсткості 0,16±0,018 мкм процес плівкоутворення проходив однаково у S. aureus і E. coli, але біоплівки були нижчої щільності, порівняно з такими, які формувалися за шорсткості 0,63±0,087 мкм. Отже, використання обладнання у молочній промисловості з шорсткістю менше 0,5 мкм дозволить зменшення прикріплення мікроорганізмів до поверхні і зниження контамінації молочних продуктів Ключові слова: мікробна адгезія, формування біоплівок, шорсткість поверхні нержавіючої сталі, процес плівкоутворення

Microbial films formation on the dairy equipment creates a serious problem, because they are difficult to eliminate by washing and disinfecting means that results in contaminating dairy products by microorganisms. The aim of the work was to study the influence of Savinase®Evity 16L proteolytic enzyme on the process of destructing biofilms, formed by Staphylococcus aureus on stainless steel with different surface roughness. It has been established, that surface roughness of stainless steel influences the process of Savinase®Evity 16L enzyme penetration in a hollow and prevents the destruction of the biofilm matrix, created by Staphylococcus aureus. It has been revealed, that after the influence of a proteolytic enzyme on Staphylococcus aureus biofilms, created on steel with roughness 0,16±0,018 mcm, the density decreased in 4,0 times (р≤0,05), comparing with a condition before processing. At roughness 0,63±0,087 mcm the density of formed biofilms decreased at the effect of Savinase®Evity 16L in 3,3times (р≤0,05) and the biofilm was characterized as a weak one. At the same time at stainless steel surfaces with roughness 2,68–0,95mcm, the density of biofilms decreased in 2,3–2,1times (р≤0,05), comparing with a condition before processing, and they were characterized as ones of the middle density. It has been also revealed, that the degradation intensity of biofilms under the influence of Savinase®Evity 16L enzyme at roughness 2,68–0,95 mcm was 1,7–1,9 times (р≤0,05) lower than at the surface with roughness 0,16±0,018 mcm. So, the revealed degradation features of a biofilm, created by Staphylococcus aureus at surfaces of stainless steel of different roughness at the influence of Savinase®Evity 16L proteolytic enzyme give a possibility to substantiate the addition of proteolytic enzymes to the composition of washing means for dairy production. It is also offered to process the surface to the roughness no more than 0,63 mcm for producing food steel for raising the effectiveness of biofilms destruction by enzymes and for the sanitary processing.

As fish are perishable foods, their storage conditions require appropriate sanitary and temperature regimes. The producers commonly use various antibiotics to stop fish’s microbiological and biochemical processes. The current research aimed to examine antibacterial residues in frozen fish (Argentina, flounder, lackerda, mackerel, capelin, salka, saithe, herring, dorado, and pink salmon) to find their influence on the quantitative content of microorganisms and to determine the sensitivity of isolated psychrotrophic bacteria to antibiotics. A total of 75 samples were collected from the fillets of frozen fish species. These fish were imported from Norway (16 samples), Vietnam (24 samples), Russian Federation (8 samples), China (14 samples), New Zealand (2 samples), Italy (2 samples), United States (4 samples), and United Kingdom (5 samples). The obtained results revealed that aminoglycosides (Gentamicin, Kanamycin, Spectinomycin, Dihydrostreptomycin, Paromomycin, and Apramycin) were in 45.6 ± 1.4% of frozen fish. The findings indicated the presence of some antibacterial residues (Nalidixic acid, antibiotics: Apramycin, Kanamycin, Tiamulin, and Nafcillin) in frozen fish, the definition of which has not been specified in the EU Regulation. This gives grounds to prohibit the use or develop standards for the maximum permissible concentration of these antibacterial substances in fish. The most common psychrotrophic bacteria isolated from frozen fish without antibacterial residues were highly sensitive to antibiotics, including Penicillin, Tetracycline groups, and Aminoglycosides. Therefore, it can be concluded that the residual levels of various biocides found in fish are a source for the expression of multi-resistance genes, which can be transmitted to consumers in the food chain.