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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).
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.
Applications
Published in Raj P. Chhabra, CRC Handbook of Thermal Engineering Second Edition, 2017
Joshua D. Ramsey, Ken Bell, Ramesh K. Shah, Bengt Sundén, Zan Wu, Clement Kleinstreuer, Zelin Xu, D. Ian Wilson, Graham T. Polley, John A. Pearce, Kenneth R. Diller, Jonathan W. Valvano, David W. Yarbrough, Moncef Krarti, John Zhai, Jan Kośny, Christian K. Bach, Ian H. Bell, Craig R. Bradshaw, Eckhard A. Groll, Abhinav Krishna, Orkan Kurtulus, Margaret M. Mathison, Bryce Shaffer, Bin Yang, Xinye Zhang, Davide Ziviani, Robert F. Boehm, Anthony F. Mills, Santanu Bandyopadhyay, Shankar Narasimhan, Donald L. Fenton, Raj M. Manglik, Sameer Khandekar, Mario F. Trujillo, Rolf D. Reitz, Milind A. Jog, Prabhat Kumar, K.P. Sandeep, Sanjiv Sinha, Krishna Valavala, Jun Ma, Pradeep Lall, Harold R. Jacobs, Mangesh Chaudhari, Amit Agrawal, Robert J. Moffat, Tadhg O’Donovan, Jungho Kim, S.A. Sherif, Alan T. McDonald, Arturo Pacheco-Vega, Gerardo Diaz, Mihir Sen, K.T. Yang, Martine Rueff, Evelyne Mauret, Pawel Wawrzyniak, Ireneusz Zbicinski, Mariia Sobulska, P.S. Ghoshdastidar, Naveen Tiwari, Rajappa Tadepalli, Raj Ganesh S. Pala, Desh Bandhu Singh, G. N. Tiwari
Most microorganisms grow best at neutral pH and only a few are able to grow at a pH value of less than 4.0. Bacteria are more selective about pH requirements than yeasts and molds which can grow over a wide range of pH. Microorganisms which can withstand low pH are known as aciduric. Bacteria require higher aw for growth as compared to that required by yeasts and molds. Gram-negative bacteria cannot grow at aw less than 0.95 whereas most gram-positive bacteria cannot grow at aw less than 0.90. However, Staphylococcus aureus can grow at aw value as low as 0.85 and halophilic bacteria can grow at a minimum aw value of 0.75. Halophilic microorganisms require a high salt concentration for growth. Most yeasts and molds can grow at a minimum aw value of 0.88 and 0.80, respectively. Xerophilic (microorganisms which can grow in low aw conditions) molds and osmophilic (microorganisms which can grow in high solute concentration) yeasts can grow at aw values as low as 0.61.
Optimization of fermentation conditions for production of neutral metalloprotease by Bacillus subtilis SCK6 and its application in goatskin-dehairing
Published in Preparative Biochemistry & Biotechnology, 2021
Fuming He, Jin Chao, Dandan Yang, Xinqing Zhang, Chuanlun Yang, Zeping Xu, Tian Jiewei, Tian Yongqiang
There are many microorganisms in saline-alkali soil, such as bacterial domain, eukaryotes, and archaea domain. Various halophilic/halotolerant bacteria on saline-alkali soil show unique metabolic mechanism and physiological structure and produce active substances with special function, such as protease and lipase.[28] In this research, we isolated a Bacillus sp. LCB14 from saline-alkali soil. A neutral protease gene was heterologous expressed by B. subtilis SCK6 and the fermentation conditions of enzyme production were optimized. Finally, the crude protease was used in the dehairing goatskin process in place of lime-sulfide.
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
In our preliminary studies, we concluded that isolated halophiles serve as the best in terms of salt tolerance mechanism that does not need any additional nutrition. It can adapt to a salty environment and feeds on the salt. According to the literature, researchers isolated halophilic microorganisms from high salt abundance environments such as salt lakes, salt ponds, Greek salt lake, the Dead Sea, etc. In this study, the organism was isolated from the coastal areas capable of growing in 20% salt, so that the halophilic microorganism does not depend on the salt concentration, but depends on the salty environment. It seems that the halophilic microorganisms are making themselves adaptable to the salty environment, is high as well as low concentration of salts. One of our conclusions is that the isolated microorganism has an electrochemical property in which salt is degraded by the organism, and the produced chemical energy is converted into electrical energy. At the same time, salt water also gets desalinated. The produced microbial electrons which are captured by the graphite and carbon electrode with the contribution of cytochromes present in the respiratory chain of the microorganism achieved in the MFC. A mixed consortium of halophilic species can produce a voltage range up to 0.624 V with varying resistance. When a single species of Halomonas salina KVCET6 is isolated from the salt brine, it can produce the maximum voltage up to 1.42 V with 2 kΩ resistance on the fifth day of the successive batch process [25]. The resistance varied during the operation period, which in turn caused the current to vary. The resistance formed was mainly due to the microbial manipulation. As it possess positively charged protein, it might neutralize the charge of electrons produced by the bacteria in the MFC.
Treatment and high value utilization of glutamic acid wastewater
Published in Preparative Biochemistry & Biotechnology, 2022
Fupeng Yu, Chen Zhao, Le Su, Song Zhang, Xin Sun, Kunlun Li, Qiulin Yue, Lin Zhao
Bacteria are the basis of fermentation. Bacillus subtilis and B. licheniformis are reported to be the efficient producers of polyglutamic acid.[4] The wastewater produced during the production of sodium glutamate has the characteristics of high acidity, high COD, and high ammonia nitrogen. It is difficult for ordinary microorganisms to survive, so the selection and breeding of strains are much important.[33] In this study, a high-salt-tolerant and high-polyglutamic acid-producing Bacillus licheniformis was screened from saline-alkali soil. After whole genome sequencing analysis, we found the salt tolerance genes nhaC, mrp and proH, which proved that their salt tolerance mechanism is related to Na+/H+ pump and synthesis of proline. Na+ is dependent on the normal growth of halophilic bacteria, and high concentration can maintain the integrity of cell wall structure and ensure normal cell function. A certain salt stress is beneficial to the growth of halophilic bacteria, however, excessive intracellular salt concentration is toxic to microbial cells. Efficient Na+/H+ antiporters exist in some salt-tolerant microorganisms and play a non-negligible role in the response of microorganisms to high-salt environmental stress.[34] By coupling with the input of H+, intracellular sodium ions are pumped out. Under high salt stress, salt-tolerant microorganisms will ingest, synthesize and accumulate affinity solutes, such as sugars, amino acids, tetrahydro pyrimidines, betaine and trehalose, etc. These small molecular weight substances are highly soluble and can not only increase intracellular water activity without affecting the normal metabolism of cells. The accumulation of affinity solutes compensates for the unbalanced internal and external osmotic pressure caused by external high osmotic pressure conditions, and relieves the stress of high-salt environment to cells to a certain extent. It is rapidly synthesized and degraded, which is beneficial for halophilic microorganisms to overcome the osmotic pressure in a high-salt environment. Proline is the main osmoprotectant in some gram-positive bacteria, such as the moderately halophilic bacteria Salinicoccus roseus and Salinicoccus hispanicus.[35] The strategies of these halophilic bacteria to accumulate high concentrations of proline mainly focus on three aspects: promoting self-synthesis, accelerating in vitro transport, or reducing degradation.