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Next Generation Industrial Biotechnology (NGIB) for PHA Production
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Halophilic bacteria are suitable microorganisms for NGIB as the high salt in the medium inhibits the growth of non-halophilic microorganisms. The family Halomonadaceae is composed of 123 different halophilic or halotolerant bacterial species including 90 Halomonas species [9]. PHA-producing halophilic bacteria were isolated from hypersaline conditions including deep-sea [10], salt lakes [11, 12], saline soil [13], and hypersaline ponds [14]. It was reported that 32 Halomonas species are known to synthesize PHA [15]. Halomonas boliviensis was isolated in the soil sample around the lake Laguna Colorada and it can tolerate a wide range of NaCl concentrations (0–25% w/v), temperature (0–45°C) and pH (6–11) in the environment [13]. This bacterium is able to produce 50–80 wt.-% PHB contents from various carbon sources including volatile fatty acids (VFAs), mono- and disaccharides as well as starch hydrolysate [16–18]. The highest PHB yield of 41 wt.% was attained after 24 hours of cultivation in air-lift reactors (ALRs) [17]. Halomonas bluephagenesis TD01 was isolated from Aydingkol Lake in Xinjiang, China [12]. H. bluephagenesis TD01 maintained contamination-free under open and continuous conditions for 14 days [12]. Engineered H. bluephagenesis TD01 was used to produce poly(3-hydroxybutyrate) (PHB) [12], copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) consisting of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) [19,20], and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) of 3-hydroxybutyrate and 4-hydroxybutyrate (4HB) [21,22].
Halophiles: Pharmaceutical Potential and Biotechnological Applications
Published in Devarajan Thangadurai, Jeyabalan Sangeetha, Industrial Biotechnology, 2017
Rebecca S. Thombre, Vaishnavi S. Joshi, Radhika S. Oke
Heavy oil biodegradation is also possible with the help of halophilic organisms, physical methods used being expensive and have other associated problems. Certain microbial metabolites like polysaccharides play a major role in oil recovery due to their bioemulsifying and surfactant activity (Banat, 1995). A halophilic bacterium, TM–1, an extreme halophile was shown to degrade heavy oil by changing the chemical properties of crude oils. This change was brought by decreasing the concentration of high-molecular alkanes in the oil. Moderate halophiles belonging to the family Halomonadaceae, isolated from highly saline sites, have been shown to utilize chloroaromatic compounds as sources of carbon and energy (Maltseva et al., 1996).
Metabolic heat coherent growth of Halomonas variabilis (HV) for enhanced production of Extracellular Polymeric Substances (EPS) in a Bio Reaction Calorimeter (BioRC)
Published in Preparative Biochemistry & Biotechnology, 2020
Saravana Raj Adimoolam, Sivanesh Nanjan Easwaran, Anusha Subramanian Mohanakrishnan, Surianarayanan Mahadevan
Halophilic bacterium producing EPS in extreme environmental conditions varies in composition and can be exploited for various applications other than being an emulsifier, flocculent and potential biosorbent in effluent treatment process industries.[20] The focus in this manuscript is on the EPS production under the hyper-saline environment by Halomonas variabilis. Halomonas variabilis belongs to the family of Halomonadaceae, order of Oceanospirillales, class of Gammaproteobacteria, phylum of Proteobacteria is a gram-negative (Figure 1a) and rod-shaped bacterium grows for a length of 0.6–1.9 µm with or without oxygen generally over the range of 5–25% NaCl in a broad variety of saline environments including estuaries, ocean, and saline lakes. They form white or yellow colonies, which later become light brown when grown on an agar plate (Figure 1b). Halomonas variabilis being a gram-negative bacterium possesses two membranes viz. the cytoplasmic membrane inside composed of phospholipids bilayer covered by an outer membrane composed of an asymmetrical bilayer having lipopolysaccharides in the outer leaflet and the associated polysaccharides often bound intact.[21]
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
The lineage is Bacteria: Proteobacteria: Gammaproteobacteria: Oceanospirillales: Halomonadaceae: Halomonas. The resulting sequence was compared with BLASTn search tool Species C is confirmed as Halomonas and the strain was named Halomonas KVCET5 (KF734085 899 bp). Species D is confirmed as Halomonas salina and the strain was named Halomonas salina KVCET 6 (KJ461947 616 bp). By comparing the resulting 16s rRNA sequence with existing microorganisms using the bioinformatics tool BLASTn, similarities of 99% and 100% were found for species C as shown in Table 2, and 99% similarity was found for species D as shown in Table 3.