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Factors affecting lactate and malate utilization by Selenomonas ruminantium
1Department of Animal and Dairy Science, The University of Georgia, Athens 30602-2771, USA. scottm@uga.cc.uga.edu
Applied and Environmental Microbiology
|February 21, 1998
Summary
Malate enhances lactate utilization by Selenomonas ruminantium, improving growth on lactate at low pH. This study investigated factors affecting organic acid co-utilization in S. ruminantium.
Area of Science:
- Microbial metabolism
- Rumen microbiology
- Bacterial physiology
Background:
- Lactate utilization by Selenomonas ruminantium is known to be stimulated by malate.
- Limited information exists on the co-utilization of lactate and malate by S. ruminantium.
Purpose of the Study:
- To evaluate factors affecting the utilization of lactate and malate by two strains of S. ruminantium (HD4 and H18).
- To understand the impact of malate on S. ruminantium growth under specific conditions.
Main Methods:
- Batch and continuous culture experiments were used to study S. ruminantium growth.
- Organic acid concentrations, pH, and bacterial protein were monitored during incubation.
Main Results:
- Both S. ruminantium strains co-utilized lactate and malate initially, producing acetate, propionate, and succinate.
- Malate utilization ceased at 7 mM malate/succinate, inhibiting lactate utilization in strain H18.
- Malate addition prevented washout of strain HD4 in continuous culture on lactate at pH 5.5, increasing bacterial protein and other metabolites.
Conclusions:
- Malate enhances the ability of S. ruminantium HD4 to grow on lactate at low pH (5.5).
- Malate co-utilization is influenced by substrate concentration and the presence of other organic acids or glucose.
- Understanding these interactions is crucial for rumen function and microbial ecology.