THE USE OF 16S RIBOSOMAL-RNA-TARGETED OLIGONUCLEOTIDE PROBES TO STUDYCOMPETITION BETWEEN RUMINAL FIBROLYTIC BACTERIA - DEVELOPMENT OF PROBES FOR RUMINOCOCCUS SPECIES AND EVIDENCE FOR BACTERIOCIN PRODUCTION
Aa. Odenyo et al., THE USE OF 16S RIBOSOMAL-RNA-TARGETED OLIGONUCLEOTIDE PROBES TO STUDYCOMPETITION BETWEEN RUMINAL FIBROLYTIC BACTERIA - DEVELOPMENT OF PROBES FOR RUMINOCOCCUS SPECIES AND EVIDENCE FOR BACTERIOCIN PRODUCTION, Applied and environmental microbiology, 60(10), 1994, pp. 3688-3696
A total of six oligonucleotide probes, complementary to the 16S rRNA,
were evaluated for quantitative and determinative studies of Ruminococ
cus albus and Ruminococcus flavefaciens. On the basis of specificity s
tudies, probes for R. albus (probe RAL196) and R. flavefaciens (probe
RFL196) were selected to quantitate these species in mixed culture. In
combination with a Fibrobacter succinogenes S85 subspecies probe (SUB
1) and a domain Bacteria (formerly kingdom Eubacteria) probe (EUB338),
they were used to quantitate these species competing in mixed culture
s for cellobiose as the carbon source. In dicultures containing R. alb
us 8 and F. succinogenes S85, competition was not observed. However, R
. flavefaciens FD-1 eventually outcompeted F. succinogenes S85 when ce
llobiose was the substrate. When R. albus 8 and R. flavefaciens FD-1 w
ere grown together on cellobiose medium, R. albus 8 outcompeted R. fla
vefaciens FD-1, resulting in undetectable R. flavefaciens 16S rRNA onl
y 1 to 3 h after inoculation, suggesting production of an antagonistic
compound by R. albus 8 during rapid growth on soluble substrates. Fur
ther, when R. albus 8, R. flavefaciens FD-I, and F. succinogenes S85 w
ere grown together in a triculture, R. flavefaciens FD 1 16S rRNA was
detectable for only 2 h after inoculation, while R. albus 8 and F. suc
cinogenes S85 showed a similar competition pattern to that of the dicu
ltures. The results show that the Ruminococcus probes were effective i
n the measurement of relative populations of selected R. albus and R.
flavefaciens strains during in vitro competition studies with F. succi
nogenes. Moreover, R. albus 8 was shown to produce a heat stable prote
in factor which causes zones of inhibition in R. flavefaciens FD-1 bac
terial lawns. This is the first demonstration of the production of a b
acteriocin-like substance by a ruminal bacterium. It is postulated tha
t bacteriocin production by ruminal fibrolytic bacteria is a mechanism
used to compete for nutrients.