Molecular Analysis of a Bacterial Chitinolytic Community in an Upland Pasture

Abstract

The effects of agricultural-improvement treatments on the chitinolytic activity and diversity of a microbial community were investigated within an upland pasture. The treatments of interest were lime and treated sewage sludge, both commonly applied to pasture land to improve fertility. Burial of chitin-containing litter bags at the field site resulted in enrichment of bacteria according to 16S rRNA fingerprinting. Chitinolyticactivity measurements showed that the highest activity occurred in those bags recovered from sludge-amended plots, which correlated well with increased counts of actinobacteria in samples from these chitin bags. Our findings suggest that sewage sludge increases the fertility of the soil in terms of chitinase activity. Ten clone libraries were constructed from family 18 subgroup A chitinases, PCR amplified from litter bags buried in soil in July 2000 or in September 2000, in a separate study. Analysis of these libraries by restriction fragment length polymorphism and sequencing showed that they were dominated by actinobacterium-like chitinase sequences. This suggests that actinobacteria have an important chitinolytic function in this soil ecosystem. Our findings showed that sludge application increased chitinolytic activity but decreased the diversity of chitinases present.

Chitinolytic Bacteria Isolated from Chili Rhizosphere: Chitinase Characterization and Its Application as Biocontrol for Whitefly (<i>Bemisia tabaci</i> Genn.)

“…Combination between chitinase and σ-toxin of B. thuringiensis were found more effective in killing pest insects (Patil et al, 2000). Spreading of chitin to a plant was also an alternative application to control pest insects, because it will induce chitinolytic bacteria to secrete chitinase (Metcalfe et al, 2002).…”

Utilization of chitinolytic bacterial isolates to control anthracnose of cocoa leaf caused by Colletotrichum gloeosporioides

“…Molecular and biochemical characterizations have revealed that chitinases, similar to other glycosyl hydrolases, are molecular in nature and can differ according to their structural organization. Enzymes can vary both within and between microbes (Kobayashi et al, 2002;Metcalfe et al, 2002). Bacterial genera Achromobacter, Bacillus, Chromobacterium, Pseudomonas and Vibrio, along with bacteria from the Flavobacterium-Cytophaga group and the Enterobacterioceae family (Donderski and Brzezińska (2001), and Streptomyces (Anitha and Rabeeth, 2010) are the common chitinase producing bacteria.…”

“…Two isolates were Gram-positive, while three was Gram-negative. Chitinolytic bacteria spread among Gram-negative and Gram -positive (Anitha and Rabeeth, 2010;Singh et al, 2008;Metcalfe et al, 2002;Folders et al, 2001).…”

Analysis of Molecular Diversity of Bacterial Chitinase Genes in the Maize Rhizosphere Using Culture-Independent Methods

“…Suzuki et al 23) have proposed subdividing the bacterial family of 18 chitinases into groups A, B, and C, based on amino acid sequence similarity in the catalytic domain. So far, information on the diversity and distribution of the bacterial chitinases is most developed for the group A enzymes, and it has been speculated that this group A is more abundant than the group B or C enzymes 16) . To further elucidate the contribution of different groups of organisms to the degradation of chitin, and to provide additional valuable information concerning the diversity of chitinase genes in terrestrial and aquatic ecosystems, several PCR primer sets for the molecular detection of bacterial chitinase genes have been designed [3][4][5]20) .…”

“…Furthermore, Williamson et al 28) have developed a primer set for the group A bacterial chitinase genes that can be used in combination with denaturing gradient gel electrophoresis (DGGE) for the analysis of soil DNA. Subsequently, by using the chitin bag method, Metcalfe et al 16) investigated bacterial chitinolytic communities in upland grassland sites that had been subjected to different soil management procedures.…”