Biofilms on the surfaces of milk-processing equipment are often a major source of contamination of dairy products. Members of the genus Bacillus appear to be among the most commonly found bacteria in dairy farms and processing plants. Bacillus species may thrive in dairy farm equipment and in dairy products since they can form robust biofilms during growth within milk. We found that fortification of milk with magnesium mitigated biofilm formation by Bacillus species, and thus could notably reduce dairy product spoilage. We also show that the mode of action of Mg2+ ions is specific to inhibition of transcription of genes involved in biofilm formation. Our further findings indicate that in the presence of Mg2+ bacterial cells are hypersensitive to the heat pasteurization applied during milk processing. Additionally, we demonstrated that enrichment of milk with magnesium improved technological properties of milk products such as soft cheeses. Finally, we report that there is a notable increase in the intestinal bioavailability potential of magnesium from supplemented milk compared with that from non-supplemented milk.
Bibliographical noteFunding Information:
This report forms contribution No. 771/17-E, 2017 Series, from the Agricultural Research Organization, the Volcani Center, Rishon LeZion, Israel. This study forms part of Noa Ben-Ishay’s M.Sc. project; Noa Ben-Ishay is a recipient of an excellence scholarship for M.Sc. students granted by The Hebrew University of Jerusalem. This work was partially supported by the Nitzan Grant of the Chief Scientist of The Ministry of Agriculture (Israel). We would like to thank Dr. Y. Chai of Northeastern University, Boston, USA for B. subtilis strains. We thank Dr. Michel Gohar, INRA, France for the B. cereus strain. We also acknowledge members of the Shemesh and Reifen laboratories for helpful discussions and technical assistance, especially Yulia Gololobova, Solange Bernstein, Ievgenia Ostrov, and Dana Inbar. We are also grateful to Mr. Eduard Belausov of the ARO for excellent technical assistance with confocal microscopy. We finally acknowledge the team of the dairy farm at the ARO for providing us with fresh raw milk for the experiments.
© 2017 The Author(s).