Ga. Dykes et al., DIFFERENTIATION OF BACILLUS ISOLATES FROM ROPEY BREAD AND THE BAKERY ENVIRONMENT USING NUMERICAL TAXONOMY, South African journal of science, 90(5), 1994, pp. 302-307
A 72-character phenotypic profile of 23 Bacillus isolates from bakery
equipment, of 34 from raw materials, 45 from ropey bread, and nine ref
erence strains, was determined. Phenotypic tests were performed using
the API 50CH and API 20E strips and additional biochemical tests. Resu
lts were analysed numerically using the simple matching coefficient wi
th single linkage clustering. A dendrogram was constructed for all 102
strains, and, in addition, separate dendrograms were constructed for
isolates from raw materials, bakery equipment surfaces and ropey bread
, each incorporating all reference strains. In the dendrogram of all s
trains, 84 isolates were recovered in 21 clusters, and all isolates co
nverged at the 90% level. Twenty-four isolates from ropey bread were r
ecovered in 10 clusters, while all isolates converged at the 99% level
. Fourteen and 18 isolates from equipment surfaces and raw materials w
ere recovered in five and six clusters, while all strains converged at
the 89% and 91% level, respectively. Conclusive differentiation of is
olates at species level was not achieved in the present study as refer
ence strains did not cluster with bakery-associated strains. The high
phenotypic similarity among all isolates from the bakery environment a
nd in particular among strains from ropey bread was notable.