An Extended Suite of Genetic Tools for Use in Bacteria of the Halomonadaceae: An Overview

Abstract

Halophilic gammaproteobacteria of the family Halomonadaceae (including the genera Aidingimonas, Carnimonas, Chromohalobacter, Cobetia, Halomonas, Halotalea, Kushneria, Modicisalibacter, Salinicola, and Zymobacter) have current and promising applications in biotechnology mainly as a source of compatible solutes (powerful stabilizers of biomolecules and cells, with exciting potentialities in biomedicine), salt-tolerant enzymes, biosurfactants, and extracellular polysaccharides, among other products. In addition, they display a number of advantages to be used as cell factories, alternative to conventional prokaryotic hosts like Escherichia coli or Bacillus, for the production of recombinant proteins: (1) their high salt tolerance decreases to a minimum the necessity for aseptic conditions, resulting in cost-reducing conditions, (2) they are very easy to grow and maintain in the laboratory, and their nutritional requirements are simple, and (3) the majority can use a large range of compounds as a sole carbon and energy source. In the last 15 years, the efforts of our group and others have made possible the genetic manipulation of this bacterial group. In this review, the most relevant and recent tools for their genetic manipulation are described, with emphasis on nucleic acid isolation procedures, cloning and expression vectors, genetic exchange mechanisms, mutagenesis approaches, reporter genes, and genetic expression analyses. Complementary sections describing the influence of salinity on the susceptibility of these bacteria to antimicrobials, as well as the growth media most routinely used and culture conditions, for these microorganisms, are also included.

Identification of two different chemosensory pathways in representatives of the genus Halomonas

“…This feature distinguishes them as useful biotechnological tools, as high salt content greatly reduces sterilization needs. Several Halomonas strains have been used in the generation of products of commercial interest as organic osmolytes [ 1 ] and different kinds of polyhydroxyalcanoates [ 2 ]. Recently, many Halomonas strains have been also associated to the degradation of xenobiotic compounds, especially hydrocarbons and aromatic compounds [ 3 , 4 ], highlighting their potential participation in bioremediation processes, especially in high salt conditions.…”

PHA Production and PHA Synthases of the Halophilic Bacterium Halomonas sp. SF2003

“…To confirm this hypothesis, several different constructions might be designed using Halomonas sp. SF2003 promoter and PHA biosynthesis genes simultaneously, and evaluated for PHA production [35,[74][75][76]. Among all the different constructions which could be tested, plasmid harboring both phaC1 and phaC2 genes, together, must be designed.…”

Insights into metabolic osmoadaptation of the ectoines-producer bacterium Chromohalobacter salexigens through a high-quality genome scale metabolic model

“…C. salexigens has been proposed, among other natural producers, as a cell factory for the production of the biostabilizing compatible solutes ectoine and hydroxyectoine [ 3 , 4 ]. The microorganism has several advantages as a cell factory: (i) it is easily cultured by using conventional media, (ii) it has broad metabolic versatility being capable of using different carbon sources [ 1 ], (iii) a high diversity of genetic tools are available for its study [ 5 ], and (iv) its genome has been sequenced [ 6 ].…”