A Multi-Strain, Biofilm-Forming Cocktail of Bacillus spp. and Pediococcus spp. Alters the Microbial Composition on Polyethylene Calf Housing Surfaces

Abstract

Application of a beneficial microbial cocktail of Bacillus spp. and Pediococcus spp. was evaluated first for adherence to polyethylene calf hutch material, and second, to determine if application in situ to individual calf hutches post-cleaning influenced surface recolonization by enteric pathogens. Three treatments were utilized: 1) no application (NC), 2) chlorine-free, distilled water (DW), or 3) an application of a microbial inoculant containing Bacillus spp. and Pediococcus spp. at a concentration of 0.4 g/m2 of hutch space (LF). Thirty-six 15 x 15 cm pieces of naive, sterile polyethylene calf hutch material received either NC or LF, were incubated at 28{degrees}C, and bacterial growth was evaluated by total aerobic plate counts at 24, 48, and 72 h post-application. Thirty polyethylene calf hutches (n = 10/treatment) were randomized to either NC, DW, or LF 24 h after cleaning. Calves were placed in the hutches 24 h after treatment application and monitored daily for 28 d. In situ surface samples were randomized by time from five unique locations within the calf hutch interior: 24 h post-cleaning, then 24 h, 7 d, 14 d, and 21 d post-application. Total aerobic plate counts and culture-independent approaches RT-qPCR and 16S amplicon sequencing were used to detect and identify the composition of the bacterial community in situ. The bacteria in the inoculant were able to successfully colonize on polyethylene, and application to individual polyethylene calf housing in situ influenced microbial diversity and reduced the presence of some undesirable bacteria on high-contact interior surfaces. IMPORTANCEDue to its multifactorial nature, neonatal calf diarrhea can be difficult to manage on farms. Clean housing environments are a critical disease control point, especially for calves less than one month of age. Application of a beneficial biofilm-forming bacterial product after cleaning of neonatal calf housing may influence the microbial communities present on the surface, particularly those that may present disease risk to calves in early life.