Resistance of rumen bacteria murein to bovine gastric lysozyme.
BACKGROUND
Lysozymes, enzymes mostly associated with defence against bacterial infections, are mureinolytic. Ruminants have evolved a gastric c type lysozyme as a digestive enzyme, and profit from digestion of foregut bacteria, after most dietary components, including protein, have been fermented in the rumen. In this work we characterized the biological activities of bovine gastric secretions against membranes, purified murein and bacteria.


RESULTS
Bovine gastric extract (BGE) was active against both G+ and G- bacteria, but the effect against Gram- bacteria was not due to the lysozyme, since purified BGL had only activity against Gram+ bacteria. We were unable to find small pore forming peptides in the BGE, and found that the inhibition of Gram negative bacteria by BGE was due to an artefact caused by acetate. We report for first time the activity of bovine gastric lysozyme (BG lysozyme) against pure bacterial cultures, and the specific resistance of some rumen Gram positive strains to BGL.


CONCLUSIONS
Some Gram+ rumen bacteria showed resistance to abomasum lysozyme. We discuss the implications of this finding in the light of possible practical applications of such a stable antimicrobial peptide.
Domínguez-Bello
María G
MG
Dept. Biology, University of Puerto Rico, Rio Piedras Campus, PO Box 23360, San Juan Puerto Rico 00931. mgdbello@cnnet.upr.edu
Pacheco
M Andreína
MA
Ruiz
Marie C
MC
Michelangeli
Fabián
F
Leippe
Matthias
M
de Pedro
Miguel A
MA
D000018:Abomasum / Q000201:enzymology*; D000818:Animals; D002417:Cattle / Q000378:metabolism* / Q000382:microbiology; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D005753:Gastric Mucosa / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007778:Lactobacillus / Q000378:metabolism; D016982:Micrococcus luteus / Q000378:metabolism*; D009113:Muramidase / Q000378:metabolism*; D010457:Peptidoglycan / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000378:metabolism; D012417:Rumen / Q000201:enzymology / Q000378:metabolism* / Q000382:microbiology; D016985:Streptococcus bovis / Q000378:metabolism
D010457:Peptidoglycan; D009113:Muramidase