Jl. Milner et al., CULTURE CONDITIONS THAT INFLUENCE ACCUMULATION OF ZWITTERMICIN-A BY BACILLUS-CEREUS UW85, Applied microbiology and biotechnology, 43(4), 1995, pp. 685-691
Bacillus cereus strain UW85 produces an antibiotic, designated zwitter
micin A, that is associated with the ability of UW85 to suppress dampi
ng-off disease of alfalfa (Medicago sativa) caused by the oomycete pat
hogen, Phytophthora medicaginis, in a laboratory bioassay. We have ide
ntified certain culture conditions that promote or suppress zwittermic
in A accumulation by UW85. Maximum accumulation was detected in supern
atants of trypticase soy broth cultures after sporulation, which is wh
en cultures of UW85 provide the greatest suppression of damping-off on
alfalfa. Inorganic amendments to trypticase soy broth cultures had th
e following effects on zwittermicin A accumulation and disease suppres
sion: phosphate (50 mM or more) reduced zwittermicin A accumulation an
d disease suppression; ferric iron (0.25-1.0 mM) enhanced zwittermicin
A accumulation and disease suppression; micronutrients (manganese, bo
ron, copper, molybdenum, zinc) had no effect on zwittermicin A accumul
ation or disease suppression. Cultures of UW85 grown in chemically def
ined minimal medium supplemented with casein hydrolysate or grown in d
efined medium containing the minimal requirements for growth supplemen
ted with five amino acids (Gin, Arg, Met, Phe, Ile) accumulated zwitte
rmicin A. In minimal medium, alfalfa seed exudate inhibited growth of
UW85, whereas alfalfa sprout exudate enhanced zwittermicin A accumulat
ion by 40%. These data indicate that the accumulation of zwittermicin
A can be modulated by specific nutrients, inorganic compounds, and pla
nt-derived factors. These results will facilitate the improvement of l
arge-scale purification of zwittermicin A, suggest appropriate conditi
ons under which to conduct further genetic and biochemical analyses, a
nd further substantiate the association between antibiotic accumulatio
n and disease suppression by UW85.