Characterization of Carboxymethylcellulase Production in Lysobacter enzymogenes

Kimberly W. Dong, Rutgers University Donald Y. Kobayashi, Department of Plant Biology and Pathology, Rutgers University

Abstract Lysobacter enzymogenes is a unique bacterial species that is antagonistic towards other microbes. It has also been characterized as a biological control agent of plant diseases, and recent studies indicate it establishes pathogenic interactions with a broad range of lower eukaryotes such as fungi, and nematodes. As its name implies, L. enzymogenes is a prolific producer of extracellular hydrolytic enzymes and secondary metabolites, which are thought to play major roles in mechanisms of Lysobacter attack on other organisms. L. enzymogenes produces carboxymethylcellulase (CMCase) activity, which is defined as degradation of cellulose and other related sugars polymers. It is important to study CMCase activity in L. enzymogenes for the three main reasons. Firstly, it may provide insight into microbial antagonism, which may in turn lead to strategies for enhancing biological control; secondly, it will provide a better understanding of the ecological significance of Lysobacter interactions with its various hosts; and lastly, by studying the offensive enzymatic capabilities for host infection by this bacterium, more information can be learned about how bacterial pathogens infect their hosts. To date, little is known about CMCase activity in L. enzymogenes at the molecular and biochemical levels. However, genes suspected to be related to cellulase activity have been identified through annotation efforts of the L. enzymogenes genome sequence. Thus far, at least five genes identified within the genome are suspected to encode for CMCase activity. One gene, a Fam 5 of glycosyl hydrolases (GHF5), has been targeted for gene knock-out mutagenesis in L. enzymogenes wildtype strain C3. Upon completing construction of the mutation, the mutant strain will be tested against various hosts for reduced pathogenicity and biological control of plant diseases.

Full Text: PDF