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Extremophiles for Sustainable Bio-energy Production
Published in Pratibha Dheeran, Sachin Kumar, Extremophiles, 2022
Amit Verma, Tirath Raj, Shulbhi Verma, Varun Kumar, Ruchi Agrawal
Halophiles are the microorganisms that have a requirement of high salt concentration, especially of sodium chloride for their growth. These are found in hypersaline habitats such as salt marshes, salty lakes, salt pans, deep salt mines and coastal and submarine pools (Setati 2010, DasSarma and DasSarma 2015). On the basis of salt concentration tolerance, they are categorized into slight halophiles (2-5% NaC1), moderate halophiles (5-15% NaC1) and extreme halophiles (15-30% NaC1) (Yin et al. 2015). The microorganisms of all three main life domains (archaea, bacteria and eukarya) have the halo tolerance (Quillaguamdn et al. 2010, Yin et al. 2015). To survive in hyper saline environments, these microorganisms have some specific physiological strategies. Haloarchaea or halophilic archaea apply a “salt-in” tactic by KC1 accumulation (equal to surrounding NaC1) within cells’ cytoplasm to counter the high saline environment. The halophilic bacteria and eukaryotes use a “salt-out” strategy to cope with high salt stress. These microorganisms accumulate or synthesize glycine betaine glycerol, ectoine, trehalose and sucrose to balance the high salt concentration of surrounding environments (Roberts et al. 2005, Oren and Mana 2003).
Linking Salinity to Microbial Biopolyesters Biosynthesis
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Martin Koller, Stanislav Obruca, Gerhart Braunegg
Haloarchaea, also called “halophilic archaea” or, previously, “halophilic archaebacteria”, represent a particular class within the phylum of the Euryarchaeota. Haloarchaea are typically found in aquatic habitats highly saturated with salt [59]. Importantly, they are classified as members of the Archaea domain, and should no longer be merged with the eubacterial group of “halobacteria”, which was introduced into the scientific literature before the existence of the two different prokaryotic domains Bacteria and Archaea was established in science. Nowadays, microbiologists call halophilic archaea “haloarchaea” in order to unambiguously distinguish them from halophilic eubacteria. Metabolites produced by haloarchaeal species are typically stable in conditions of high salinity and temperature, which makes them useful for special industrial applications [60]. Haloarchaeal proteins and enzymes function at such salinity levels at which their eubacterial equivalents are no longer active, which makes haloarchaeal enzymes appropriate for salt-challenged processes and applications under dehydration conditions [61–63]. As an example, bacteriorhodopsin, a light-driven photon-pump found, e.g., in Halobacterium halobium [64,65], or the purple membrane protein present in various haloarchaea [66,67] are expected to become widely implemented in artificial retinas, photoelectric devices, or holograms. Moreover, thanks to their gas vesicles [68,69] and S-layer glycoproteins [70], haloarchaea have exceptional potential to be utilized as drug delivery vehicles and as workhorses in the emerging field of nanobiotechnology [60]. Haloarchaea can also be implemented in bioremediation of hypersaline environments [71,72] contaminated by, e.g. aromatic hydrocarbons [73], chlorate [74], or crude oil [75,76]. PHA and extracellular polysaccharides (EPS) produced by such microbes are biodegradable, compostable, and biocompatible, and therefore have the potential to substitute established recalcitrant plastics and other polymers [60].
Bioelectricity production and desalination of Halomonas sp. – the preliminary integrity approach
Published in Biofuels, 2019
R. Uma Maheswari, C. Mohanapriya, P. Vijay, K.S. Rajmohan, M. Gopinath
Halophiles are nourished in environments that control the growth of other microorganisms. Hypersaline environments are unique in nature compared with other geological formations associated with saline brines like petroleum reserves and estuaries. Halophiles consume salt and produce stable, unique biomolecules which can be helpful in practical applications through bioremediation process because industries use salts in high amounts and release excess salts through running water and fresh water. Researchers have found 195–250 million years aged halophilic archa bacteria (Haloarchaea) from rock salt, as reported by Fendrihan et al. [12]. As it can persist for many years, this is the best bacteria to use for the continuous bioprocess operation.