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Halophilic Microbiome
Published in Ajar Nath Yadav, Ali Asghar Rastegari, Neelam Yadav, Microbiomes of Extreme Environments, 2021
Mrugesh Dhirajlal Khunt, Rajesh Ramdas Waghunde, Chandrashekhar Uttamrao Shinde, Dipak Maganlal Pathak
Halophilic and halotolerant microbes grow under high ionic concentration and low water activity. Additionally, there may be a more severe problem if salinity changes due to water evaporation and water dilution during rainfall. In order to cope with this osmotic stress, halophiles have developed many alternate strategies; an accumulation of osmolytes is one of them (Yancey et al. 1982). Halophiles accumulate osmolytes, also called ‘compatible solutes’ are molecules that usually compensate the osmotic pressure (Brown 1976) and thereby reduce the osmotic shock in a saline environment. Therefore, compatible solutes impart survival against the deleterious effect on cell growth and metabolism due to salinity. Halophiles could accumulate wide varieties of compatible solutes such as amino acids, polyols and its derivatives, different nitrogen containing compounds (Rhodes and Hanson 1993; Hagemann and Pade 2015), as well as amino acid derivatives like glycine-betaine and ectoine (Ventosa et al. 1998; Waditee et al. 2005). Another potential compatible solute Nε-acetyl lysine is usually synthesized by Haloacillus halophilus, however, it has to still be confirmed by further studies (Saum et al. 2013). Thus, halophiles are a source of a wide range of compatible solutes, however there is need to explore them in different biotechnological applications.
Anaerobic Degradation of Organic Compounds in Hypersaline Environments: Possibilities and Limitations
Published in Donald L. Wise, Bioprocessing and Biotreatment of Coal, 2017
We have studied the mechanisms enabling the anaerobic halophilic bacteria to withstand the high salt concentrations in the medium, in view of the fact that different groups of halophilic microorganisms possess different mechanisms to balance the cell contents osmotically with the external medium. For example, aerobic extremely halophilic archae-bacteria (the genera Halobacterium and Halococcus) maintain high salt concentrations within the cells, a high sodium chloride concentration in the external medium being balanced by a high potassium chloride concentration inside. A different strategy of adaptation to high salt concentrations is found in halophilic and halotolerant eubacteria, halophilic cyanobacteria, and eukaryotic algae such as Dunaliella: In these organisms the enzymatic processes within the cells are inhibited by high salt concentrations, which precludes the existence of such high salt concentrations within the cells. Different organic “compatible solutes” have been shown to maintain an osmotic balance of the cell cytoplasm with the outside medium, while still permitting a high level of enzymatic activity. The obligately anaerobic, moderately halophilic eubacteria H. praevalens and H. halobius were found to contain high intracellular potassium concentrations (0.76 to 2.05 M, not well correlated with the external NaCl concentration), and high intracellular sodium concentrations (0.28 to 2.6 M, increasing with increasing extracellular sodium concentration). The sum of intracellular potassium and sodium concentrations approximated the total cation concentration of the medium, and internal chloride concentrations in H. praevalens equaled the external chloride concentration. No organic “compatible solutes” were found in significant concentrations [29].
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 salt-loving bacteria, and can be classified as slightly halophile, moderately halophile, and extremely halophile based on the concentration of sodium chloride present in the environment. Halophiles are distributed all over the world in hypersaline environments – specifically, natural hypersaline brines in arid, coastal and even deep-sea locations, as well as in artificial salterns used to mine salts from the sea. The novel behavior of these halophiles and the potential for large-scale culturing means halophiles find wide application in biotechnology. Halophiles are distinguished by their need for hypersaline conditions for growth. They may be classified according to their salt requirements: slight halophiles grow optimally at (2–5%) sodium chloride; moderate halophiles grow optimally at (5–20%) sodium chloride; and extreme halophiles grow optimally above (20–30%) sodium chloride. In contrast, non-halophiles grow optimally at less than 2% sodium chloride. Many halophile and halotolerant microorganisms can grow and withstand a high salt concentration with the requirement or tolerance for salts sometimes based on nutritional factors present in the environment [11].
Atlantic Forest’s and Caatinga’s semiarid soils and their potential as a source for halothermotolerant actinomycetes and proteolytic enzymes
Published in Environmental Technology, 2023
Marghuel A. Vieira Silveira, Saara M. Batista dos Santos, Débora Noma Okamoto, Itamar Soares de Melo, Maria A. Juliano, Jair Ribeiro Chagas, Suzan P. Vasconcellos
Halophilic and halotolerant microorganisms have developed physiological mechanisms and genetic characteristics to achieve evolutionary success in unfeasible environments, many of these characteristics acquired over time, in addition to helping with the deleterious effects that such environments may display and contribute to the biotechnological potential and economic value as a source of important new bioactives. It is estimated that a single strain of actinobacteria has the capacity to produce 10–20 secondary metabolites, their bioprospecting for technological purposes has been stimulated and strategies for applying their products have been analysed [16,52,53].
Role of halotolerant and chitinolytic bacteria in phytoremediation of saline soil using spinach plant
Published in International Journal of Phytoremediation, 2020
Muhammad Anees, Arshad Qayyum, Muhammad Jamil, Fayyaz ur Rehman, Muhammad Abid, Muhammad Saqib Malik, Muhammad Yunas, Kalim Ullah
Reclamation of saline soils to improve crop productivity using novel biotechnological tools such as bioremediation offers one of the acceptable alternatives to the chemical application for the purpose. Halotolerant bacteria are those which can grow in high salt conditions as well as in non-saline conditions. Mostly they adopt various mechanisms in salty areas such as production of exopolysaccharides, stress proteins, restricted entry or efflux of Na+, and sodium-dependent potassium uptake (Apte and Bhagwat 1989; Goel et al. 1997). The halotolerant bacteria may be used for the bioremediation of saline soils and degradation of toxic compounds (Arora et al.2014). Moreover, the bacteria may also help plants evade salt stress, for instance, by production of ACC deaminase (Ramadoss et al. 2013). In addition to this, a bacterial strain with multiple characters that may or may not be directly related to each other, but however, supporting toward the plant and at the end boosts the plant growth can always be interesting to quest for. A halotolerant chitinolytic bacterial strain can be an example in that case, helping salt remediation as well as combating the plant pathogens/pests. The chitinolytic bacteria have the ability to counter the fungal plant diseases and improve plant growth (Naing et al.2014; Anees et al. 2019). Chitinases are the enzymes that can hydrolyze the chitin present in the fungal walls. A similar way can be to try together the two types of bacteria to get the favorable results which was one of the reasons why the present study was conducted. A few supporting documents can be found in the literature such as the amendment of soil with chitin boosting the chitinolytic soil microbiome was found to increase the rate of bioremediation of soils contaminated with heavy metals (Rae and Gibb 2003). It was reported that Virgibacillus marismortui species produced chitinases and had a halotolerant nature as well (Essghaier et al.2012).