Purpose: This study was to apply bacteriophages to reduce H2S production from raw poultry products and decontaminate SPB biofilm on surfaces of rendering processing environment.
Methods: A mixture of 9 selected SPB-specific bacteriophages was inoculated to raw poultry by-products such as chicken meat (fresh and spoiled), offal and feather, and SPB biofilm on stainless steel and plastic surfaces. A greenhouse study was performed to simulate the conditions for transporting raw materials to rendering plant. Multiplicity of infection (MOI) of 100 or 1000 was used for phage treatment. The population of SPB was enumerated using a trypticase soy agar (TSA) - H2S selective medium and the amount of H2S production was determined using either test strips impregnated with lead acetate or a H2S monitor.
Results: H2S production by SPB in various raw poultry by-products including fresh chicken meat artificially inoculated with SPB, spoiled chicken meat, offal and feather was reduced ranging from 25 to 71% by bacteriophages under laboratory condition. MOI of 1,000 was more effective than MOI of 100 in reducing H2S production by SPB for all treatments. Phage treatment also reduced H2S production by 30~85% in raw poultry by-products in a greenhouse study. Furthermore, bacteriophages was able to reduce SPB biofilm population on surfaces of steel and plastic by 1.5~2 log and 0.4~1.4 log CFU/cm2, respectively, under both laboratory and rendering plant conditions in spring and summer.
Significance: Control of H2S production from raw poultry by-products and in rendering environment can not only provide a safer working environment for workers but also produce high quality rendered animal meals for feed industry.