Investigation into the antibacterial activity of mesoporous zirconium phosphate against beer-spoilage bacteria

Technical Session 10: Microbiology I Session
Guangtian Zhou, School of Food and Bio-engineering,Shandong Institute of Light Industry, 250353, Jinan, Shandong, China
Co-author(s): Xinxia Ge, School of Food and Bioengineering, Shandong Institute of Light Industry, Jinan, China; Wen He and Xiaoyong Du, Key Laboratory of Glass and Functional Ceramics, Shandong Polytechnic University, Jinan, China; Xiaolei Dong, School of Food and Bioengineering, Shandong Institute of Light Industry, Jinan, China

ABSTRACT: Hygiene is a major concern of the brewing industry. The aim of this study was to examine the antimicrobial effect of mesoporous zirconium phosphate (M-Zrp), which is an inorganic nanometer material with an aperture of 2~50 nm that could be used as an effective antibacterial agent against beer-spoilage bacteria. Template synthesis of M-Zrp is an important method. A biological template has a lot of advantages in terms of non-toxic and environmental protection. M-Zrp’s were produced by natural fresh yeast through bio-mimetic synthesis, which conforms to the green chemical concept advocated at the present. The antibacterial activity of M-Zrp from the yeast bio- template was investigated by the inhibition zone test. The impact of particle size, concentration, and action time on antibacterial behavior was examined. The results showed that M-Zrp has bacteriostatic activity against Saccharomyces diastaticus, Candida albicans, Pediococcus damnosus, and Escherichia coli. But it had no effect on Lactobacillus brevis and Pectinatus cerevisiiphilus. The mean diameters of the inhibition zone were 11.67, 12.37, 8.64, and 14.36 mm, respectively. Antibacterial activity increased as the concentration of M-Zrp increased and particle size decreased. Within a certain range, the effect was enhanced with the prolonging of action time. The minimal inhibitory concentrations (MIC) were found by spectroscopic method to be 10 mg/L for S. diastaticus, C. albicans, and E. coli, and 25 mg/L for P. damnosus. When M-Zrp was exposed to bacteria for 24 hr, the average sterilization rate can reach 96.78% at MIC of 12.5 mg/L and up to 98.54% after 36 hr. The morphology of S. diastaticus before and after treatment with M-Zrp was observed by means of polarization microscope. It was observed that the presence of M-Zrp damages the membrane of the bacterium at first, and further, penetrates the cell wall and interacts with internal components, resulting in leakage of intracellular contents and eventually the death of bacterial cells. Our findings suggest that M-Zrp exhibits effective antimicrobial properties and could be exploited for the application of antibacterial coatings or additives for the food and beverage industries.

Guangtian Zhou received his B.S. degree in bioengineering from Shandong Institute of Light Industry, Jinan, China, in 1982. He was then employed with the Jinan Beer Group as a brewer. Guangtian studied in Doemens Akademie, Munich, Germany, from August 1987 until November 1988. After graduation, he became chief brewer of the Jinan Beer Group. Since July 1994, Guangtian has functioned as professor, tutor of M.S. degree students, and the director of the China-Germany Beer Technology Center in the School of Food and Bio-engineering, Shandong Institute of Light Industry, teaching and researching beer production. At present, he serves as an editor of China Brewing and a council member of Shandong Society for Microbiology.