Characterization of a Surface-Active Protein Extracted from a Marine Strain of Penicillium chrysogenum.

Paola Cicatiello,Luca De Stefano,Daria Maria Monti,Paola Giardina,Principia Dardano,Ganna Petruk,Ilaria Stanzione,Gerardino D’Errico,Addolorata De Chiaro,Leila Birolo

doi:10.3390/ijms20133242

Abstract

Marine microorganisms represent a reservoir of new promising secondary metabolites. Surface-active proteins with good emulsification activity can be isolated from fungal species that inhabit the marine environment and can be promising candidates for different biotechnological applications. In this study a novel surface-active protein, named Sap-Pc, was purified from a marine strain of Penicillium chrysogenum. The effect of salt concentration and temperature on protein production was analyzed, and a purification method was set up. The purified protein, identified as Pc13g06930, was annotated as a hypothetical protein. It was able to form emulsions, which were stable for at least one month, with an emulsification index comparable to that of other known surface-active proteins. The surface tension reduction was analyzed as function of protein concentration and a critical micellar concentration of 2 μM was determined. At neutral or alkaline pH, secondary structure changes were monitored over time, concurrently with the appearance of protein precipitation. Formation of amyloid-like fibrils of SAP-Pc was demonstrated by spectroscopic and microscopic analyses. Moreover, the effect of protein concentration, a parameter affecting kinetics of fibril formation, was investigated and an on-pathway involvement of micellar aggregates during the fibril formation process was suggested.

Highlights

Most of the emulsifiers currently used are synthetic; in the era of green technology, great interest is being given to surface-active biomolecules [1]
Marine microorganisms represent a reservoir of new promising secondary metabolites
In an oil polluted environment, these molecules play a specific role of binding to dispersed hydrocarbons and oils, preventing them from merging together, increasing their access and availability for biodegradation. These amphiphilic molecules mainly produced by microorganisms occur in nature as different kinds of compounds characterized by low molecular weight, i.e., glycolipids, lipopeptides, phospholipids, and fatty acids, or high molecular weight, i.e., amphipathic polysaccharides, proteins, lipopolysaccharides, lipoproteins or complex mixtures of these biopolymers [7]

Summary

Introduction

Most of the emulsifiers currently used are synthetic; in the era of green technology, great interest is being given to surface-active biomolecules [1]. The constant research of efficient surface-active compounds, biosurfactants (BSs), and bioemulsifiers (BEs), with improved thermo-physical properties could make several industrial processes more sustainable. These molecules find applications in cosmetics, pharmaceutics, food processes, and bioremediation [4,5,6]. In an oil polluted environment, these molecules play a specific role of binding to dispersed hydrocarbons and oils, preventing them from merging together, increasing their access and availability for biodegradation These amphiphilic molecules mainly produced by microorganisms occur in nature as different kinds of compounds characterized by low molecular weight, i.e., glycolipids, lipopeptides, phospholipids, and fatty acids, or high molecular weight, i.e., amphipathic polysaccharides, proteins, lipopolysaccharides, lipoproteins or complex mixtures of these biopolymers [7]

Methods

Results

Conclusion