A comparison of media and cultural conditions for identification of Bacillus larvae in honey

SUMMARY

The sensitivity of five solid media for detection of Bacillus larvae spores in honey samples; J agar, MYPGP agar, brain heart infusion (BHIT) agar, Colombia agar and horse blood agar was compared in air or under 5% C0₂. MYPGP agar is superior to all other media tested for detection of low spore levels of B. larvae in honey. Incubation under 5% C0₂ enhances growth considerably, especially for MYPGP agar and J agar. The plating efficacy described here, where an average of 23% of inoculated spores germinated on MYPGP agar, is higher than reported elsewhere for B. larvae. Thus, contamination levels as low as 200 B. larvae spores/g of honey can be detected with more than 95% probability on MYPGP agar incubated under 5% C0₂ if 12 or more plates are inoculated.

Keywords:

• Bacillus larvae
• honey
• culture media
• J agar
• MYPGP agar
• brain heart infusion agar
• Colombia agar
• horse blood agar
• carbon dioxide