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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
Alkaliphiles are microorganisms that are optimally colonized at pH 9.0 and above 9.0 usually between pH 10.0 and 12.0. They do not grow near neutral pH (6.5-7.0). These microorganisms are naturally found in neutral or high alkaline environments like soda lakes, alkaline soils of sub ground level, carbonate springs and deep sea. Sometimes, alkaliphiles are also found in acidic soils. Alkaliphiles have two main groups on the basis of physiology, alkaliphiles and haloalkaliphiles. Haloalkaliphiles need high salinity (~ 33% NaC1) with alkaline environment for their optimal growth. This group of extremophiles comprises several types of microorganisms including bacteria (spore forming aerobic and non-spore forming anaerobic), archaea and fungi (yeast) (Chinnathambi 2015, Sarethy et al. 2011). Alkaliphiles tolerate strong alkaline environment by maintaining the pH homeostasis (Padan et al. 2005). They balance or decrease cytoplasmic pH by enhanced production of acids from deamination of amino acids and sugar fermentation (Richard and Foster 2004). They also modify (acidic) their cell surfaces for attraction and attachment of cations for pH homeostasis through activation of monovalent cation/proton antiporters (Wang et al. 2004, Kitada et al. 2000, Swartz et al. 2005).
Biological Agents
Published in Katarzyna Majchrzycka, Małgorzata Okrasa, Justyna Szulc, Respiratory Protection Against Hazardous Biological Agents, 2020
Neutrophils are microorganisms with an optimal pH for growth close to neutral (6–7.5) and they constitute the majority of known bacteria. Acidophilic microorganisms are organisms that are capable of functioning in an environment with a pH of < 4. They are characteristic of extreme environments such as iron and sulphur deposits, mine waters and volcanic soil. Lactic and acetic acid bacteria, numerous species of yeasts and moulds, and algae are classified as acidophiles. Alkaliphiles are microorganisms with an optimal pH for growth in the range of 8–11. This group includes many species of bacteria, including pathogenic Vibrio cholerae or Streptococcus pneumoniae, archaea and cyanobacteria. Among alkaliphiles, a group of microorganisms can be distinguished, which, apart from high pH, also requires high concentrations of sodium chloride, NaCl, for optimal growth. Such microorganisms are referred to as haloalkaliphiles and occur in extremely alkaline and saline environments such as salt lakes, salines and geothermal springs. These include sulphur oxidising bacteria and nitrifying bacteria [Duckworth 1996; Libudzisz 2019].
Alkaliphilic Bacteria and Thermophilic Actinomycetes as New Sources of Antimicrobial Compounds
Published in Devarajan Thangadurai, Jeyabalan Sangeetha, Industrial Biotechnology, 2017
Suchitra B. Borgave, Meghana S. Kulkarni, Pradnya P. Kanekar, Dattatraya G. Naik
Alkaliphilic microorganisms have many industrial applications. Many of them produce compounds of industrial interest and also they possess useful physiological properties which can facilitate their exploitation for commercial purposes (Ulukanli and Digrak, 2002). Microbial communities in natural alkaline environments have attracted attention because of possible biotechnological use of enzymes and metabolites from such organisms. The information on alkaliphilic bacteria producing antimicrobial compounds is summarized in Table 2.3.
A systematic review on MICP technique for developing sustainability in concrete
Published in European Journal of Environmental and Civil Engineering, 2023
Santosh Ashok Kadapure, Umesh B. Deshannavar, Basavaraj G. Katageri, Poonam S. Kadapure
The pH of concrete is around 12–13. In these alkaline conditions, the selected bacteria should survive or undergo in dormant stage. The bacteria which can undergo in dormant stage or survive at higher pH are called alkaliphiles. Extreme alkaliphiles adapts to harsh environment through the evolutionary modification of lipid, protein structure and mechanisms to maintain the proton motive force in an alkaline environment. Sporosarcina pasteurii the most common bacteria used in MICP technique has optimum pH of 8 and calcite formation was found to decrease in the pH range of 8.7 to 9.5. Above this pH, activity of the enzyme is found to decrease which retards biomineralization process and low quantity of calcite formation may take place. At lower pH, carbonate gets dissolved with less amount of calcite precipitation (Wang et al., 2016).
Removal of alkalinity and metal toxicity from incinerated biomedical waste ash by using Bacillus halodurans
Published in Bioremediation Journal, 2022
Harsimranpreet Kaur, Rafat Siddique, Anita Rajor
Alkaliphilic microorganisms can play a crucial role because of its biotechnological applications due to enzymes viz. proteases, cellulases, xylanases that are stable at high pH (>9.5) and temperature (>50 °C) (Kumar et al. 2014; Gupta et al. 2008; Engle et al. 1995). The alkaliphiles microorganisms have great potential in bioremediation and dealing with toxicity. The enzymes present in the alkaliphiles enable them to resist the alkaline environment to biodegrade certain xenobiotics. The cell surface of alkaliphile can maintain the intracellular pH values near neutral in the alkaline environment of pH 10–13. The presence of Na + ions in the growth medium plays a pivotal role in the adaptation of alkaliphilic Bacillus species at high pH values. This method is called bioremediation, in which the bacteria stabilizes the content of the toxic metal through its natural metabolic process.
Mechanical and durability performance of sustainable bacteria blended fly ash concrete: an experimental study
Published in International Journal of Sustainable Engineering, 2020
Santosh A. Kadapure, Girish Kulkarni, K.B Prakash, Poonam S. Kadapure
The bacterial strain considered for this research is B. sphaericus which fulfilled the necessary criteria for survival in harsh environment. This strain was procured from National Collection of Industrial Microorganisms, Pune. B. sphaericus bacteria are alkaliphilic (alkali-resistant) spore-forming bacteria (Jianyun et al. 2012). Liquid medium solution for B. sphaericus was prepared by using nutrient broth solution supplemented with urea and CaCl2 (Khaliq and Ehsan 2016). The medium was sterilised by autoclaving for 20 min at 120°C. The selected strain was introduced in the medium through sterilised loop.