Fate of Clostridium estertheticum in biofilms and in response to conventional and novel sanitizers.

Blown pack spoilage (BPS) is a major concern to the meat industry and is primarily caused by Clostridium estertheticum, a psychrophilic spore-forming, anaerobic bacterium. We investigated the survival mechanisms of C. estertheticum and the efficacy of various sanitizers against C. estertheticum spores. When cultured alone or with Pseudomonas poae at 10°C in a biofilm reactor, viable C. estertheticum vegetative cells were recovered only sporadically from stainless steel coupons. However, they were consistently and constantly recovered from planktonic cultures under various conditions for up to 96 h. Spores attached to stainless steel coupons (5.76 ± 0.03 log CFU/cm2) were treated with water, PowerFoam, BioDestroy, peroxyacetic acid, UV-C LED, or plasma-activated water. BioDestroy and UV-C reduced (P < 0.05) the spore counts by ≥ 4.5 log units, while the other treatments had reductions, if at all, by < 1 log. Heating at 60 or 80°C before UV-C exposure did not affect spore reduction. When C. estertheticum spores were co-cultured with P. poae, Leuconostoc gelidum or Leu. gelidum and Latilactobacillus sakei in biofilm reactors at 10°C for up to 96 h, recovery of spores from coupons was not affected by incubation time or companion cultures. The companion cultures all developed biofilms. Treatments with BioDestroy or UV-C reduced viable spore counts in biofilms to mostly below the detection level. Interestingly, P. poae and Lat. sakei may sensitize spores to subsequent treatment. Genome analysis revealed genes encoding biosynthetic gene clusters in these two strains, in particular bacteriocins.