Complex Carbohydrates Reduce the Frequency of Antagonistic Interaction Among Bacteria Degrading Cellulose and Xylan

Document Type

Article

Publication Date

3-1-2017

Department

Biological Sciences

School

Biological, Environmental, and Earth Sciences

Abstract

Bacterial competition for resources is common in nature but positive interactions among bacteria are also evident. We speculate that the structural complexity of substrate might play a role in mediating bacterial interactions. We tested the hypothesis that the frequency of antagonistic interactions among lignocellulolytic bacteria is reduced when complex polysaccharide is the main carbon source compared to when a simple sugar such as glucose is available. Results using all possible pairwise interactions among 35 bacteria isolated from salt marsh detritus showed that the frequency of antagonistic interactions was significantly lower on carboxymethyl cellulose (CMC)–xylan medium (7.8%) than on glucose medium (15.5%). The two interaction networks were also different in their structures. Although 75 antagonistic interactions occurred on both media, there were 115 that occurred only on glucose and 20 only on CMC–xylan, indicating that some antagonistic interactions were substrate specific. We also found that the frequency of antagonism differed among phylogenetic groups. Gammaproteobacteria and Bacillus sp. were the most antagonistic and they tended to antagonize Bacteroidetes and Actinobacteria, the most susceptible groups. Results from the study suggest that substrate complexity affects how bacteria interact and that bacterial interactions in a community are dynamic as nutrient conditions change.

Publication Title

FEMS Microbiology Letters

Volume

364

Issue

5

First Page

1

Last Page

7

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