Characterization of mesophilic bacilli in faeces of feedlot cattle.
OBJECTIVE
To determine the identity and composition of mesophilic Bacillus spp. in faeces sampled from feedlot cattle.


RESULTS
Faecal samples from 10 feedlot cattle were analysed. The total aerobic spore count increased from 4.6 x 10(4) CFU g(-1) (before feedlotting, day 0) to 1.6 x 10(6) CFU g(-1) (feedlot for day 76). A total of 150 randomly selected spore isolates (60 each from days 0 and 76 cattle, 30 from feed) were speciated using a Bacillus group-specific PCR-amplified ribosomal DNA restriction analysis technique (Wu et al. 2006). At day 0, Bacillus subtilis and Bacillus cereus predominated with a prevalence of 58.3% and 26.7%, respectively, whereas three species, B. subtilis (50.0%), Bacillus licheniformis (27.6%) and Bacillus clausii (20.0%) predominated in day 76 faecal samples. Of these, only the first two species were present in feed samples at a frequency of 70% and 30% respectively. All B. cereus isolates on day 0, possessed at least one of three enterotoxin genes (nheA, nheB and nheC) but these were completely eliminated after a period of feedlotting. All isolates of B. licheniformis were genotypically heterogeneous according to pulsed-field gel electrophoresis analysis.


CONCLUSIONS
Cattle faeces contain large numbers of Bacillus spores representing different mesophilic species. Stable faecal populations of particular Bacillus spp. mimicking those found in feed, were subsequently established by feedlotting.


CONCLUSIONS
The results obtained and methods used in this study will help to investigate the indigenous Bacillus composition in the gastrointestinal tract of cattle and will further guide the administration of Bacillus probiotics.
Wu
X-Y
XY
Department of Immunology and Microbiology, Elizabeth Macarthur Agriculture Institute, NSW Department of Primary Industries, Camden, NSW, Australia.
Walker
M
M
Vanselow
B
B
Chao
R-L
RL
Chin
J
J
D000818:Animals; D001407:Bacillus / Q000235:genetics / Q000302:isolation & purification*; D001409:Bacillus cereus / Q000235:genetics / Q000302:isolation & purification; D001412:Bacillus subtilis / Q000235:genetics / Q000302:isolation & purification; D002417:Cattle; D015169:Colony Count, Microbial / Q000379:methods; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D004768:Enterotoxins / Q000235:genetics; D005243:Feces / Q000382:microbiology*; D005798:Genes, Bacterial / Q000235:genetics; D015183:Restriction Mapping / Q000379:methods; D013171:Spores, Bacterial / Q000235:genetics / Q000302:isolation & purification
D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D004768:Enterotoxins