title: The potential of the endolysin Lysdb from Lactobacillus delbrueckii phage for combating Staphylococcus aureus during cheese manufacture from raw milk.
abstract: Phage endolysins have received increased attention in recent times as potential antibacterial agents and the biopreservatives in food production processes. Staphylococcus aureus is one of the most common pathogens in bacterial food poisoning outbreaks. In this study, the endolysin Lysdb, one of the two-component cell lysis cassette of Lactobacillus delbrueckii phage phiLdb, was shown to possess a muramidase domain and catalytic sites with homology to Chalaropsis-type lysozymes. Peptidoglycan hydrolytic bond specificity determination revealed that Lysdb was able to cleave the 6-O-acetylated peptidoglycans present in the cell walls of S. aureus. Turbidity reduction assays demonstrated that Lysdb could effectively lyse the S. aureus live cells under acidic and mesothermal conditions. To further evaluate the ability of Lysdb as a potential antibacterial agent against S. aureus in cheese manufacture, Lactobacillus casei BL23 was engineered to constitutively deliver active Lysdb to challenge S. aureus in lab-scale cheese making from raw milk. Compared with the raw milk, the viable counts of S. aureus were reduced by 10(5)-fold in the cheese inoculated with the engineered L. casei strain during the fermentation process, and the pathogenic bacterial numbers remained at a low level (10(4) CFU/g) after 6 weeks of ripening at 10 °C. Taken together, all results indicated that the Lysdb has the function as an effective tool for combating S. aureus during cheese manufacture from raw milk.
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, 27 Shanda Nanlu, Jinan, 250100, People's Republic of China.|School of Environmental Science and Engineering, Shandong University, Jinan, 250100, People's Republic of China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, 27 Shanda Nanlu, Jinan, 250100, People's Republic of China.
authors.forename: YongPing
authors.initials: Y
authors.lastname: Xin
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, 27 Shanda Nanlu, Jinan, 250100, People's Republic of China.
authors.forename: Chenchen
authors.initials: C
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, 27 Shanda Nanlu, Jinan, 250100, People's Republic of China.
authors.forename: Xudong
authors.initials: X
authors.lastname: Ouyang
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, 27 Shanda Nanlu, Jinan, 250100, People's Republic of China. kongjian@sdu.edu.cn.
authors.forename: Jian
authors.initials: J
authors.lastname: Kong
mesh_terms: D000818:Animals; D001435:Bacteriophages / Q000201:enzymology* / Q000235:genetics; D002417:Cattle; D002611:Cheese / Q000382:microbiology*; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D005285:Fermentation; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control; D005511:Food Handling; D048668:Lactobacillus delbrueckii / Q000235:genetics / Q000821:virology*; D008892:Milk / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000502:physiology; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D014764:Viral Proteins; D010450:Endopeptidases; C001143:endolysin
keywords: Antibacterial; Endolysin; Lactobacillus casei; Staphylococcus aureus