Strategy for screening metagenomic resources for exocellulase activity using a robotic, high-throughput screening...

Area of Science:

• Biochemistry
• Enzymology
• Metagenomics

Background:

• Exocellulases are crucial for cellulose degradation, releasing glucose and cellobiose.
• Previous exocellulase screening was hindered by assay limitations, high substrate costs, and low enzyme activity.
• Endocellulase activity often overshadows exocellulase activity in traditional assays.

Purpose of the Study:

• To develop and validate a robotic, high-throughput screening (HTS) system for direct exocellulase detection.
• To overcome limitations of previous screening methods for exocellulases.
• To identify novel exocellulase enzymes from metagenomic sources.

Main Methods:

• A robotic HTS system was employed for enzyme screening.
• Cell growth was monitored via optical density over 11-14 hours at 37°C with agitation.
• Released methylumbelliferyl groups from 4-methylumbelliferyl-β-D-cellobioside were quantified using fluorescence detection.

Main Results:

• The HTS system achieved activity verification of over 10^4 clones per day.
• Four novel exocellulase clones (CelEx-SF301, CelEx-SF309, CelEx-BR12, CelEx-BR15) were identified.
• These enzymes were isolated from 29,006 metagenomic fosmid clones from soil and rumen microbes.

Conclusions:

• A robust and efficient HTS method for direct exocellulase screening has been established.
• This approach significantly accelerates the discovery of new enzymes from diverse metagenomic libraries.
• The developed system holds potential for screening various metagenomic resources for novel enzymatic activities.