RESEARCH PAPER
Microbial contamination level and microbial diversity of occupational environment in commercial and traditional dairy plants
 
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Central Institute for Labour Protection – National Research Institute, Warsaw, Poland
CORRESPONDING AUTHOR
Agata Stobnicka-Kupiec   

Central Institute for Labour Protection – National Research Institute, Czerniakowska 16 Street, 00-701, Warsaw, Poland
 
KEYWORDS
TOPICS
ABSTRACT
Objective:
The aim of this study was to assess microbial contamination of the air and surfaces at workplaces in commercial (CD) and traditional (TD) dairies.

Material and methods:
Bioaerosol (impactor) and surface (swab) samples were collected in CD and in TD. Bacterial and fungal concentrations in the air and on surfaces were calculated and all isolated microorganisms taxonomically identified, based on their morphological, biochemical and molecular features.

Results:
Average concentrations of bacterial aerosol ranged between 70–860 CFU/m3 and 265–14639 CFU/m3, while for fungal aerosol were between 50–290 CFU/m3 and 55–480 CFU/m3 in CD and TD, respectively. Average bacterial concentrations on surfaces ranged between 1.0–49.7 CFU/cm2 and 0.2–60.4 CFU/cm2, whereas average fungal surface contamination ranged between 0–2.7 CFU/cm2 and 0–4.6 CFU/cm2 in CD and TD, respectively. Qualitative analysis revealed mainly the presence of saprophytic microorganisms; however, several pathogenic strains (Staphylococcus aureus, Streptococcus intermedius, Clostridium perfringens, Actinomyces spp., Streptomyces spp., Candida albicans) were also isolated from both the air and surface samples in the studied dairies.

Conclusions:
The air and surfaces in TD were more polluted than those in CD; however, in both types of dairies, the levels of microbial contaminants did not exceed respective threshold limit values. Nevertheless, the presence of pathogenic microorganisms may increase health risk for dairy workers and influence the quality of products. Hence, proper hygienic measures should be introduced and performed to guarantee high microbial quality of both production processes and milk products.

ACKNOWLEDGEMENTS
This study was based on the results of a research project undertaken within the scope of the IV stage of the National Programme ‘Improvement of safety and working conditions’, partly supported in 2017–2019, within the scope of research and development, by the Ministry of Science and Higher Education/National Centre for Research and Development, with the Central Institute for Labour Protection/National Research Institute as main co-ordinator of the programme (Project No. II.N.16). The authors express their thanks all employees of the dairy farms who assisted in the performance and completion of this study.
 
REFERENCES (70)
1.
IDF – International Dairy Federation. The Economic Importance of Dairying IDF Factsheet. 2013; https://www.fil-idf.org/wp-con....
 
2.
Holah JT. Industrial Monitoring: Hygiene in Food Processing. In: Melo LF, Bott TR, Fletcher M, Capdeville B, editors. Biofilms — Science and Technology. NATO ASI Series (Series E: Applied Sciences). vol. 223, Dordrecht: Springer; 1992, p. 645–659.
 
3.
Duszkiewicz-Reinhard W, Grzybowski R, Sobczak E. Theory and practice in food microbiology, Warsaw, Poland: University of Life Sciences, 2003.
 
4.
Dhanashekar R, Akkinepalli S, Nellutla A. Milk-borne infections. An analysis of their potential effect on the milk industry. GERMS . 2012; 2(3): 101–109.
 
5.
Fugl A, Berhe T, Kiran A, Hussain S, Laursen MF, Bahl MI, Hailu Y, Sørensen KI, Guya ME, Ipsen R, Hansen EB. Characterisation of lactic acid bacteria in spontaneously fermented camel milk and selection of strains for fermentation of camel milk. Int Dairy J. 2017; 73: 19–24.
 
6.
Khedid K, Faid Lex M, Mokhtari A, Soulaymani A, Zinedine A. Characterization of lactic acid bacteria isolated from the one humped camel milk produced in Morocco. Microbiol Res. 2009; 164(1): 81–91.
 
7.
Oliver SP, Jayarao BM, Almeida RA. Foodborne pathogens in milk and the dairy farm environment: Food Safety and Public Health Implications. Foodborne Path Dis. 2005; 2(2): 115–129.
 
8.
Barros LS, Sóglia SLO, Rodrigues MJ, Branco MPC. Aerobic and anaerobic bacteria and Candida species in crude milk. J Microbiol Antimicrobials. 2011; 3(8): 206–212.
 
9.
Delavenne E, Mounier J, Asmani K, Jany JL, Barbier G, Le Blay G. Fungal diversity in cow, goat and ewe milk. Int J Food Microbiol. 2011; 151(2): 247–51.
 
10.
Lavoie K, Touchette M, St-Gelais D, Labrie S. Characterization of the fungal microflora in raw milk and specialty cheeses of the province of Quebec. Dairy Sci Tech. 2012; 92(5): 455–68.
 
11.
FDA US Food and Drug Administration (FDA). Department of Health and Human Services, Office of Food additive safety, Available at: https://www.accessdata.fda.gov... https://www.accessdata.fda.gov... https://www.accessdata.fda.gov....
 
12.
Centers for Disease Control and Prevention (CDC). Healthy living – raw (unpasteurized) milk. 2018; https://www.cdc.gov/features/r....
 
13.
Murphy SC, Martin NH, Barbano DM, Wiedmann M. Influence of raw milk quality on processed dairy products: How do raw milk quality test results relate to product quality and yield? J Dairy Sci. 2016; 99(12): 10128–10149.
 
14.
Gücükoğlu A, Kevenk TO, Uyanik T, Cadirci O, Terzi G, Alişarli M. Detection of enterotoxigenic Staphylococcus aureus in raw milk and dairy products by multiplex PCR. J Food Sci. 2012; 77(11): 620–623.
 
15.
Montel MC, Buchin S, Mallet A, Delbes-Paus C, Vuitton DA, Desmasures N, Berthier F. Traditional cheeses: rich and diverse microbiota with associated benefits. Int J Food Microbiol. 2014; 177: 136–154.
 
16.
Kongo JM. Lactic acid bacteria as starter-cultures for cheese processing: past, present and future developments, lactic acid bacteria. R & D for Food, Health and Livestock Purposes. InTech., 2013; doi: https://doi.org/10.5772/55937.
 
17.
Leroy F, De Vuyst L. Lactic acid bacteria as functional starter cultures for the food fermentation industry. Trends Food Sci Tech. 2004; 15(2): 67–78.
 
18.
Simon X, Duquenne P. Assessment of workers’ exposure to bioaerosols in a French cheese factory. Ann Occup Hyg. 2014; 58(6): 677–692.
 
19.
Wessels S, Axelsson L, Bech Hansen E, De Vuyst L, Laulund S, Lähteenmäki L, Lindgren S, Mollet B, Salminen S, von Wright A. The lactic acid bacteria, the food chain, and their regulation. Trends in Food Science & Technology. 2004; 15: 498–505.
 
20.
Dalphin JC, Illig S, Pernet D, Dubiez A, Debieuvre D, Teyssier-Cotte C, Depierre A. Symptoms and respiratory function in a group of Gruyère cheese processors in Comté. Revue des Maladies Respiratoires. 1990; 7(1): 31–37.
 
21.
Zeilfelder B, Chouanière D, Reboux G, Vacheyrou M, Milon A, Wild P, Oppliger A. Health effects of occupational exposure in a dairy food industry, with a specific assessment of exposure to airborne lactic acid bacteria. J Occup Env Med. 2012; 54(8): 969–973.
 
22.
Lange JL, Thorne PS, Kullman GJ. Determinants of culturable bioaerosol concentrations in dairy barns. Ann Agric Environ Med. 1997; 4(2): 187–194.
 
23.
Matković K, Vučemilo M, Vinković B, Pavičić Ž, Tofant A, Matković S. Effect of microclimate on bacterial count and airborne emission from dairy barns on the environment. Ann Agric Environ Med. 2006; 13(2): 349–354.
 
24.
European Committee for Standardization (CEN). Workplace atmosphere—guidelines for measurement of airborne microorganisms and endotoxin (Standard No. EN 13098:2007). Brussels, Belgium: CEN; 2007.
 
25.
Engelhart S, Glasmacher A, Simon A, Exner M. Air sampling of Aspergillus fumigates and other thermotolerant fungi: comparative performance of the Sartorious MD8 airport and the Merck MAS-100 portable bioaerosol sampler. Int J Hyg Environ Health. 2007; 210: 733–739.
 
26.
Lagier LC, Edouard S, Pagnier I, Mediannikov O, Drancourt M, Raoult D. Current and past strategies for bacterial culture in clinical microbiology. Clin Microbiol Rev. 2015; 28(1): 208–236.
 
27.
Klich MA. Identification of common Aspergillus species. Utrecht, The Netherlands: Centraalbureau voor Schimmelcultures, 2002.
 
28.
Owen MK, Ensor DS, Sparks LE. Airborne particle sizes and sources found in indoor air. Atmospheric Env. Part A. General topics. 992; 26: 2149–2162.
 
29.
Samson RA, Hoekstra ES, Frisvad JC. Introduction to food- and airborne fungi. 7th ed. Utrecht, The Netherlands: Centraalbureau voor Schimmelcultures; 2004.
 
30.
St-Germain G, Summerbell R. Identifying filamentous fungi. Belmont, USA: Star; 1996.
 
31.
Zhang H, You C. A universal PCR method and its application in sequence-based identification of microorganisms in dairy. Int Dairy J. 2018; 85: 41–48.
 
32.
Bosshard PP, Zbinden R, Abels S, Böddinghaus B, Altwegg M, Böttger EC. 16S rRNA gene sequencing versus the API 20 NE System and the VITEK 2 ID-GNB card for identification of nonfermenting Gram-negative bacteria in the clinical laboratory. J Clin Microbiol. 2006; 44(4): 1359–1366.
 
33.
Frank JA, Reich CI, Sharma S, Weisbaum JS, Wilson BA, Olsen GJ. Critical evaluation of two primers commonly used for amplification of bacterial 16S rRNA genes. Appl Environ Microbiol. 2008; 74: 2461–2470.
 
34.
White TJ, Bruns T, Lee S, Tailor S. Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics, In: Innins, M.A., Gelf, D.H., Sninsky, J.J., White, T.J., editors. PCR protocols. A guide to methods and applications. USA, San Diego: Academic Press, 1990, p. 315–322.
 
35.
Directive 2000/54/EC of the European Parliament and of the Council of 18 September 2000 on the protection of workers from risks related to exposure to biological agents at work. Official Journal of European Union Lex, 262, 21, 21–45.
 
36.
Ordinance of the Minister of Health of April 22, 2005, on hazardous biological agents in the work environment and the protection of health of workers occupationally exposed to them. J Laws, 81, 716.
 
37.
Opiyo BA, Wangoh J, Njage PKM. Microbiological performance of dairy processing plants is influenced by scale of production and the implemented food safety management system: a case study. J Food Protect. 2013; 70(6): 975–983.
 
38.
Salustiano VC, Andrade NJ, Brandão SCC, Azeredo RMC, Lima SAK. Microbiological air quality of processing areas in a dairy plant asevaluated by the sedimentation technique and a one-stage air sampler. Brazilian J Microbiol. 2003; 34: 255–259.
 
39.
Belestioids E, Ghikas D, Kalantzi K. Incorporation of microbiological and molecular methods in HACCP monitoring scheme of moulds and yeasts in a Greek Dairy Plant: A case study -11th International Congress on Engineering and Food (ICEF11). Procedia Food Sci. 2011; 1: 1051–1059.
 
40.
Mbareche H, Veillette M, Bilodeau GJ, Duchaine C. Fungal aerosols at dairy farms using molecular and culture techniques. Sci Total Env. 2019; 653: 253–263.
 
41.
Radha K, Nath LS. Studies on the air quality in a dairy processing plant. Indian J Vet Animal Sci Res. 2014; 43(5): 346–353.
 
42.
Microgen Bioproducts Ltd. A Guide to Environmental Microbiological Testing for the Food Industry (www.microgenbioproducts.com/wp...).
 
43.
Górny RL, Anczyk E, Dutkiewicz J. The role of standards and limit values for biological agents in protection of workers health—a view from Europe (presentation PS04–57). In: XVIII World Congress on Safety and Health at Work, 2008.
 
44.
Górny RL, Mainelis G, Dutkiewicz J, Anczyk E. Bioaerosols in the environment – should we apply reference values? (Presentation T04–016). In: European Aerosol Conference, 2007.
 
45.
Pośniak M. Harmful agents in the working environment—admissible values. Poland, Warsaw: CIOP–PIB, 2018.
 
46.
Mostert JF, Jooste PJ. Quality control inthe dairy industry. In: Robinson RK, editor. Dairy Microbiology Handbook-The Microbiology of Milk and Milk Products. New York: John Wiley and Sons; 2002, p. 655–736.
 
47.
Luck H, Gavron H. Quality control in the dairy industry. In: Robinson RK, editor. Dairy Microbiology–the Microbiology of Milk products. London: Elsevier Applied Science; 1990, p. 345–392.
 
48.
Gołofit-Szymczak M, Górny RL. Microbiological Air Quality in Office Buildings Equipped with Different Ventilation Systems. Indoor Air. 2018; 28: 792–805.
 
49.
Fysun O, Kern H, Wilke B, Langowski HC. Evaluation of factors influencing dairy biofilm formation in filling hoses of food-processing equipment. Food Bioprod Process. 2019;113: 39–48.
 
50.
Godlewska K. Hygiene: Quick tests for checking the cleanliness of production areas. Dairy Business Forum. 2015; 1/2015: 20.
 
51.
Herbert M, Donovan T, Manger P. A study of the microbial contamination of working surfaces in a variety of food premises using traditional swabbing technique and commercial contact slides. Public Health Laboratory Service. UK; Ashford, 1990.
 
52.
Dijk R, van den Berg D, Beumer RR, de Boer E, Dijkstra A, Kalkmand P, Stegeman H, Uyttendaele M, Veenedaal H. Microbiologie van Voedingsmiddelen: methoden, principes an criteria (vierdedruk). Uitgeverij Keesing Noordervliet. The Netherlands; Houten, 2007.
 
53.
Gilmour A, Harvey J. Staphylococci in milk and milk products. J Appl Bacteriology. 1990; 69: 147–166.
 
54.
Shinefield HR, Ruff NL. Staphylococcal infections: a historical perspective. Infectious Disease Clinics of North America. 2009; 23(1): 1–15.
 
55.
Whiley RA, Beighton D, Winstanley TG, Fraser HY, Hardie JM. Streptococcus intermedius, Streptococcus constellatus, and Streptococcus anginosus (the Streptococcus milleri group): association with different body sites and clinical infections. J Clin Microbiol. 1992; 30(1): 243–244.
 
56.
Tong SYC, Davis JS, Eichenberger E, Holland TL, Fowler VG. Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management. Clin Microbiol Rev. 2015; 28(3): 603–661.
 
57.
de Oliveira LP, de Barros LSS, Silva VC, Cirqueira MG. Study of Staphylococcus aureus in raw and pasteurized milk consumed in the Reconcavo area of the State of Bahia. J Food Process Tech. 2011; 2: 6.
 
58.
Nam H, Lim SK, Kang HM, Kim JM, Moon JS, Jang KC, Joo YS, Kang M, Jung SC. Antimicrobial resistance of streptococci isolated from mastitic bovine milk samples in Korea. J Vet Diagn Investig. 2009; 21: 698–701.
 
59.
Alves VF, Niño-Arias FC, Pitondo-Silva A, de Araújo Frazilio D, de Oliveira Gonçalves L, Toubas LC, Sapateiro Torres IM, Oxaran V, Dittmann KK, De Martinis ECP. Molecular characterisation of Staphylococcus aureus from some artisanal Brazilian dairies. Int Dairy J. 2018; 85: 247–253.
 
60.
Schlegelová J, Babák V, Holasová M, Konstantinová L, Necidová L, Šišák F, Vloková H, Roubal P, Jaglic Z. Microbial contamination after sanitation of food contact surfaces in dairy and meat rocessing plants. Czech J Food Sciences. 2010; 20(5): 450–461.
 
61.
Yerlikaya O. Starter cultures used in probiotic dairy product preparation and popular probiotic dairy drinks. Food Sci Tech. 2014; 34(2): 221–229.
 
62.
Roy D. Technological aspects related to the use of bifidobacteria in dairy products. Lait. 2005; 85: 39–56.
 
63.
Mollet B, Salminen S, von Wright A. The lactic acid bacteria, the food chain, and their regulation. Trends Food Sci Tech. 2004; 15: 498–505.
 
64.
Osama R, Khalifa M, Al-Toukhy M, Al-Ashmawy M. Prevalence and antimicrobial resistance of Clostridium perfringens in milk and dairy products. World J Dairy Food Sci. 2015; 10(2): 141–146.
 
65.
Voidarou C, Bezirtzoglou E, Alexopoulos A, Plessas S, Stefanis C, Papadopoulos I, Vavias S, Stavropoulou E, Fotou K, Tzora A, Skoufos I. Occurrence of Clostridium perfringens from different cultivated soils. Anaerobe. 2011; 17(6): 320–324.
 
66.
Svensson B, Ekelund K, Ogura H, Christiansson A. Characterisation of Bacillus cereus isolated from milk silo tanks at eight different dairy plants. Int Dairy J. 2004; 14(1): 17–27.
 
67.
Brandl H, Fricker-Feer C, Ziegler, D., Mandal, J., Stephan, R., Lehner, A., 2014. Distribution and identification of culturable airborne microorganisms in a Swiss milk processing facility. J Dairy Sci. 97, 240–246.
 
68.
Garnier L, Valence F, Mounier J. Diversity and Control of Spoilage Fungi in Dairy Products: An Update. Microorganisms. 2017; 5: 42.
 
69.
Dworecka-Kaszak B, Krutkiewicz A, Szopa D, Kleczkowski M, Biegańska M. High Prevalence of Candida Yeast in Milk Samples from Cows Suffering from Mastitis in Poland. Sci World J. 2012; 196347.
 
70.
Kim J, Sudbery P. Candida albicans, a major human fungal pathogen. J Microbiol. 2011; 49: 171.
 
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