An Alternative Bacterial Expression System Using Bacillus pumilus SG2 Chitinase Promoter

A Contemporary Appraisal on Impending Industrial and Agricultural Applications of Thermophilic-Recombinant Chitinolytic Enzymes from Microbial Sources

The ability of chitinases to degrade the second most abundant polymer, chitin, into potentially useful chitooligomers and chitin derivatives has not only rendered them fit for chitinous waste management but has also made them important from industrial point of view. At the same time, they have also been recognized to have an imperative role as promising biocontrol agents for controlling plant diseases. As thermostability is an important property for an industrially important enzyme, various bacterial and fungal sources are being exploited to obtain such stable enzymes. These stable enzymes can also play a role in agriculture by maintaining their stability under adverse environmental conditions for longer time duration when used as biocontrol agent. Biotechnology has also played its role in the development of recombinant chitinases with enhanced activity, thermostability, fungicidal and insecticidal activity via recombinant DNA techniques. Furthermore, a relatively new approach of generating pathogen-resistant transgenic plants has opened new ways for sustainable agriculture by minimizing the yield loss of valuable crops and plants. This review focuses on the potential applications of thermostable and recombinant microbial chitinases in industry and agriculture.

Molecular Engineering of the Geobacillus stearothermophilus α-Amylase and Cel5E from Chlostridium thermocellim; In Silico Approach

Background

Considering natural thermal stability, Geobacillus stearothermophilus amylase and Cel5E from Clostridium thermocellum are good candidates for industrial applications. To be compatible with the industrial applications, this enzyme should be stable in the high temperatures, so any improvement in their thermal stability is valuable.

Objectives

Using in silico approach and identifying point mutations in the structure amylase of G. stearothermophilus and Cel5E from C. termocellum we tried to increase thermal stability of the enzymes along with their catalytic activity to reach a new industrial amylase with higher thermostability and an improved function.

Materials and Methods

In this study we predicted the 3D structure of the enzymes, then simulated the molecular docking study using MolDock, PLANTS, and Lamarkian genetic algorithm as scoring functions for the docking and in silico engineering of the protein aiming to increase the thermal stability and catalytic activity.

Results

A series of thermal stability increasing point mutations were exerted around the active site of the enzyme, then by docking procedure, the binding affinity was measured and finally a list of mutations which theoretically improved the increased thermal stability as well as catalytic activity were proposed.

Conclusions

Based on the in silico results obtained the modified enzymes seems to be suitable candidates for considering in both laboratory and industrial scales.

Expression and Secretion of Cyan Fluorescent Protein (CFP) in B. subtilis using the Chitinase Promoter from Bacillus pumilus SG2

Background:

Improved cyan fluorescent protein (ICFP) is a monochromic, green fluorescent protein (GFP) derivative produced by Aequorea macrodactyla in a process similar to GFP. This protein has strong absorption spectra at wavelengths 426-446 nm. ICFP can be used in cell, organelle or intracellular protein labeling, investigating the protein-protein interactions as well as assessing the promoter activities.

Methods:

In our previous study, the promoters of two chitinases (ChiS and ChiL) from Bacillus pumilus SG2 were assessed in B. subtilis and their regulatory elements were characterized. In the present study, icfp was cloned downstream of several truncated promoters obtained in the former study, and ICFP expression was evaluated in B. subtilis.

Results:

Extracellular expression and secretion of ICFP were analyzed under the control of different truncated versions of ChiSL promoters grown on different media. Results from SDS-PAGE and fluorimetric analyses showed that there were different expression rates of CFP; however, the UPChi-ICFP3 construct exhibited a higher level of expression and secretion in the culture medium.

Conclusion:

Our presented results revealed that inserting this truncated form of Chi promoter upstream of the ICFP, as a reporter gene, in B. subtilis led to an approximately ten fold increase in ICFP expression.