Antibacterial peptides from thermophilic bacteria
Abstract
It is becoming interestingly apparent that innovations of the classical antibiotics are not effective, that induces need for novel drugs. Peptide antibiotics exhibit a group of secondary metabolites with hydrophobic and cyclic structures containing d-amino acidc like compounds with more resistant to proteolytic degradation. Bacterial peptides can possess bactericidal, fungicidal, metal chelating and immunomodulation activities. Several bacteriocins are active as food preservation, resulting in foods with more naturally preserved and rich in nutritional properties. Antimicrobial peptides used against infections are isolated mainly from mesophilic bacterial species. Novel antibacterial peptides from thermophilic species are more stable at higher temperatures and pH, and can be improved by variation of cultivation conditions. These cells can growth either autotrophically or heterotrophically. Under mixotrophic conditions can utilize pyruvate or hydrogen with thiosulfate. The present review provides a general overview on primary structure of selected antibiotic peptides and their potential for industrial purposes as well as environmental and biotechnological applications.
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Introduction
The genus Geobacillus contains, more than 25 species, which were detected in thermophilic areas around the world. Geobacillus thermodenitrificans N680-2 produces a nisin analogue termed geobacillin I (Fig.1 B). This peptide was produced by heterologous expression in Escherichia coli. NMR results showed that geobacillin I incorporates seven thioester cross-lings and demonstrates increased stability compared with nisin. Antimicrobial activity of geobacillin I is similar to nisin A. The genome of G.stearothermophilus NG80-2 contains a gene product with a ring topology distinct from any known lantibiotics. The geobacillin II exhibits antibiotic activity against Bacillus only (Garg et al., 2012). Only bacteriocins type I nisin, mutacin (Fig. 1C) and planeosporin are active against multidrug resistant Gram-positive bacteria (Severina et al., 1998; Fontana et al., 2006). Bacteriocin production is stabile even at 55 °C and is dependent on the time of incubation, pH and concentrations of nitrogen.
Conclusion
The post-genomic era will provide much new information on target sites and interactions of protein-protein and protein nucleic acids interactions. One of ultimate goals is to adopt order structures of molecules that can past through cell membranes and interact with specific targets. Peptide antibiotics from thermophiles are suitable for the handling of the structure and are more resistant to proteolytic degradation. Peptides can be safer and more selective than small molecular drugs. There is no need for chemical purification and subsequent separation of isomers. There are several hundred of polypeptides that are in various steps of clinical development. There is need for new antimicrobial peptides with hydrophobicity and -helicity for their activity against mycobacteria in the fight against drug resistant tuberculosis. Natural peptides can be used as food preservatives, chemotherapeutics, and efficient detergents.