Isolation, Characterisation, and Lipase Production of a Cold-Adapted Bacterial Strain Pseudomonas sp. LSK25 Isolated from Signy Island, Antarctica.

Leelatulasi Salwoom,Raja Raja Abd Rahman,Peter Convey,Mohd Mohamad Ali,David Pearce,Abu Salleh,Fairolniza Mohd Shariff

doi:10.3390/molecules24040715

Abstract

In recent years, studies on psychrophilic lipases have been an emerging area of research in the field of enzymology. This study focuses on bacterial strains isolated from anthropogenically-influenced soil samples collected around Signy Island Research Station (South Orkney Islands, maritime Antarctic). Limited information on lipase activities from bacteria isolated from Signy station is currently available. The presence of lipase genes was determined using real time quantification PCR (qPCR) in samples obtained from three different locations on Signy Island. Twenty strains from the location with highest lipase gene detection were screened for lipolytic activities at a temperature of 4 °C, and from this one strain was selected for further examination based on the highest enzymatic activities obtained. Analysis of 16S rRNA sequence data of this strain showed the highest level of sequence similarity (98%) to a Pseudomonas sp. strain also isolated from Antarctica. In order to increase lipase production of this psychrophilic strain, optimisation of different parameters of physical and nutritional factors were investigated. Optimal production was obtained at 10 °C and pH 7.0, at 150 rev/min shaking rate over 36 h incubation.

Highlights

Extreme environments including those of Antarctica have been successfully colonised by numerous microorganisms and the biodiversity of these microorganisms is becoming increasingly well documented.These microorganisms, which are typically psychrophilic or psychrotolerant, have developed various adaptations enabling them to survive the harsh effects of such environments [1,2]
They are known as extremophiles due to their ability to adapt to low temperature and other extreme environmental stresses [5]
Only320 isolates produced a zone of clearance (Figure surrounding eachagar colony after d isolates incubation at 4 ◦ C, produced a zone of clearance (Figure 1a) surrounding each colony after 3 d incubation at 4 °C, indicating theindicating hydrolysis of tributyrin by the lipolytic activity of the isolates

Summary

Introduction

Extreme environments including those of Antarctica have been successfully colonised by numerous microorganisms and the biodiversity of these microorganisms is becoming increasingly well documented These microorganisms, which are typically psychrophilic or psychrotolerant, have developed various adaptations enabling them to survive the harsh effects of such environments [1,2]. True psychrophiles are able to grow at temperatures below 10 ◦ C They are known as extremophiles due to their ability to adapt to low temperature and other extreme environmental stresses [5]. Since their entire cellular processes can take place in a cold environment it is crucial that all components of the cell, including metabolism and protein synthesis, are well adapted to function at low temperatures. Pivotal features include the maintenance of functional membranes, the evolution of cold-adapted enzymes, and the inclusion of a range of structural features which a high

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Discussion

Conclusion