Factors affecting the activity of bovicin HC5, a bacteriocin from Streptococcus bovis HC5: release, stability and binding to target bacteria.
OBJECTIVE
To determine the factors affecting the release, stability and binding of bovicin HC5 to sensitive bacteria.


RESULTS
Stationary phase Streptococcus bovis HC5 cultures had little cell-free bovicin HC5 activity until the final pH was <5.0, and even more bacteriocin was released by treatment with acidic NaCl (pH 2.0, 100 mmol l(-1)). Cultures grown with Tween 80 had more cell-free bovicin HC5 than untreated controls, but this nonionic detergent enhanced activity rather than release. Bovicin HC5 binding to S. bovis JB1 (a susceptible strain) was greater at pH values <6.0. Bovicin HC5 bound other sensitive Gram-positive bacteria, but not Gram-negative species. Cultures retained most of their activity for 35 days, but only if the final pH was <5.6. If the final pH was >5.6, peptidases destroyed much of the activity.


CONCLUSIONS
Bovicin HC5 remains cell associated until the culture pH is <5.0, but it can be easily dissociated from the cell surface by acidic NaCl. It is highly stable in acidic environments and only binds sensitive bacteria at pH values <6.0.


CONCLUSIONS
Streptococcus bovis HC5 does not have generally regarded as safe status. However, bovicin HC5 has a broad spectrum of activity and sensitive bacteria do not become resistant. Based on these results, bovicin HC5 may be a useful bacteriocin model.
Houlihan
A J
AJ
Department of Microbiology, Cornell University, NY 14853, USA.
Russell
J B
JB
D001430:Bacteriocins / Q000378:metabolism* / Q000493:pharmacokinetics; D003470:Culture Media; D005947:Glucose / Q000378:metabolism; D006094:Gram-Positive Bacteria / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010447:Peptide Hydrolases / Q000378:metabolism; D011136:Polysorbates / Q000378:metabolism; D012995:Solubility; D016985:Streptococcus bovis / Q000378:metabolism*; D013501:Surface-Active Agents / Q000378:metabolism
D001430:Bacteriocins; D003470:Culture Media; D011136:Polysorbates; D013501:Surface-Active Agents; C514465:bovicin HC5, Streptococcus bovis HC5; D010447:Peptide Hydrolases; D005947:Glucose