Alkalophiles

Alkalophiles are a class of extremophiles capable of survival in alkaline (pH roughly 8.5–11) environments, growing optimally around a pH of 10. At such high pH, the normal cellular functions are detrimentally affected for mesophilic organisms. The alkalophiles successfully manage stability of DNA, plasma membrane, and function of cytosolic enzymes, as well as other unfavorable physiological changes at such an elevated pH. A recent development in NextGen sequencing technology facilitates identifying uncultivable organisms amongst the extreme environments. In recent years, distribution of alkalophiles was reported from Soda Lake, marine environments, saline deserts, and natural thermal vents to natural water bodies. Although alkalophiles were first reported in 1889, their enzymatic and industrial applications still make them an interesting area of research. This chapter provides basic information on environmental distribution, taxonomy, physiology, bioenergetics, and survival mechanism and enzymes produced by alkalophilic organisms.

Influence of meromixia on the distribution of zoobenthos and zooplankton in the salt soda lake Doroninskoe

Meromictic soda lakes are considered models of reservoirs of the Early Proterozoic. Lake Doroninskoe belongs to a rare type of moderately salty alkaline soda lake with a carbonate type of salinity and pronounced meromixia. Studies and publications on the zoobenthos of the lake are rare. In 2005–2007, studies of zoobenthos and zooplankton of the lake were carried out. Meromixia of the water column caused the stable presence of zooplankton only in a layer up to 4 m. The distribution of the taxonomic abundance, quantitative development and structure of zoobenthos in the lake corresponds to the stratification of the water column into mixolimnion, chemocline and monimolimnion. Bottom biotopes and water column layers deeper than 4 m were uninhabited, which is probably due to the lack of oxygen and high hydrogen sulphide content in the bottom water layers due to meromixia. A similar distribution of zooplankton in Lake Doroninskoe and its mesocosm model was revealed.

Composition And Key-Influencing Factors of Bacterial Communities Active In Sulfur Cycling of Soda Lake Sediments

Bacteria are important participants in sulfur cycle of the extremely haloalkaline environment, e.g. soda lakes. The effects of physicochemical factors on the composition of sulfide-oxidizing bacteria (SOB) and sulfate-reducing bacteria (SRB) in soda lakes have remained elusive. Here, we surveyed the communities structure of total bacteria, SOB and SRB based on 16S rRNA, soxB and dsrB gene sequencing, respectively, in five soda lakes with different physicochemical factors. The results showed that the dominant bacteria in soda lakes sediments belonged to the phyla Proteobacteria, Bacteroidetes, Halanaerobiaeota, Firmicutes and Actinobacteria. SOB and SRB were widely distributed in lakes with different physicochemical characteristics，and the community composition were different . In general, salinity and inorganic nitrogen sources (NH4+-N, NO3--N) were the most significant factors. Specifically, the communities of SOB, mainly including Thioalkalivibrio, Burkholderia, Paracoccus, Bradyrhizobium, and Hydrogenophaga genera, were remarkably influenced by the levels of NH4+-N and salinity. Yet, for SRB communities, including Desulfurivibrio, Candidatus Electrothrix, Desulfonatronospira, Desulfonatronum, Desulfonatronovibrio, Desulfonatronobacter and so on, the most significant determinants were salinity and NO3--N. Besides, Rhodoplanes played a significant role in the interaction between SOB and SRB. From our results, the knowledge regarding the community structures of SOB and SRB in extremely haloalkaline environment was extended.

Adaptive strategies of the microbial community in meromictic soda Lake Doroninskoye (Transbaikalia, Russia)

The adaptive strategies of biogeochemical systems are considered as a criterion for natural fluctuations of the territory using the example of the microbial community in meromictic soda Lake Doroninskoye (Transbaikalia, Russia). The features of the phylogenetic and functional diversity of the microbial community of the lake have been investigated. In the off-season, a change in the dominant component of the community in the chemocline of the lake was established. During the ice period, the lake is dominated by metabolically flexible, anoxygenic, photoheterotrophic non-sulfuric purple bacteria Rhodospirillaceae and Rhodobacteraceae (class Alphaproteobacteria), which can switch from anoxic photosynthesis to aerobic chemotrophic metabolism. During the open water period, facultative aerobic bacteria of the families Enterobacteriaceae (class Gammaproteobacteria) and Alcaligenaceae (class Betaproteobacteria) predominate, which switch to denitrification in the absence of oxygen.

The blast, the quake, and the bomb: A guide to high-energy events in western Nevada, USA

ABSTRACT This guide presents an eight-hour, in-person tour of intersecting geologic and human history in western Nevada, USA. A 25 megaton phreatomagmatic blast created a mile-wide (1.6-km-wide) maar, now filled by Soda Lake. The magnitude 7 Dixie Valley earthquake ripped along more than 45 km of the Stillwater Range front in 1954. The 12 kiloton Shoal nuclear test in 1963 created a 50-m-wide cavity in solid granite.

Determination of important enzymes and antimicrobial resistances of gram-positive haloalkaliphilic bacteria isolated from Salda Lake

As an extreme environment, soda lakes harbor various haloalkaliphilic microorganisms. Salda Lake is one of the natural soda lake (pH˃9) in Turkey. Haloalkaliphiles are unique microorganisms in their ability to live in high alkaline and high saline conditions, and play an important role in biodegradation and bioremediation of hydrocarbons. Hence, the aims of this study were to isolate haloalkaliphilic bacteria from water sample of Salda Lake, to identify these isolates by both conventional and molecular methods, to screen their industrially important enzymes, and to investigate their antimicrobial resistance profiles. Six isolates were identified as Bacillus horneckiae, Bacillus subtilis, Bacillus paramycoides, Bacillus pumilus, Staphylococcus epidermidis, Bacillus haynesii according to 16S rRNA gene sequencing analysis. The industrially important enzymes (amylase, cellulase, pullulanase, lipase, urease, protease, caseinase, oxidase, catalase) were produced by haloalkaliphilic isolates. These enzymes maybe used in alkaline and saline industrial processes. Although Bacillus subtilis was susceptible to all antibiotics, other isolates showed resistance to at least one antibiotic. The resistance against antibiotics were found as ampicillin/sulbactam 83%, amoxycillin/clavulanic acid 83%, ampicillin 67%, mupirocin 67%, chloramphenicol 50%, tetracycline 50%, imipenem 50%, meropenem 50%, cefadroxil 17%. These bacteria may have develope resistance to antibiotics that entering their natural environment in different ways.

Microbial community of soda Lake Van as obtained from direct and enriched water, sediment and fish samples

Soda lakes are saline and alkaline ecosystems that are considered to have existed since the first geological records of the world. These lakes support the growth of ecologically and economically important microorganisms due to their unique geochemistry. Microbiota members of lakes are valuable models to study the link between community structure and abiotic parameters such as pH and salinity. Lake Van is the largest endroheic lake and in this study, bacterial diversity of lake water, sediment, and pearl mullet (inci kefali; Alburnus tarichi), an endemic species of fish which are collected from different points of the lake, are studied directly and investigated meticulously using a metabarcoding approach after pre-enrichment. Bacterial community structures were identified using Next Generation Sequencing of the 16S rRNA gene. The analysis revealed that the samples of Lake Van contain high level of bacterial diversity. Direct water samples were dominated by Proteobacteria, Cyanobacteria, and Bacteroidota, on the other hand, pre-enriched water samples were dominated by Proteobacteria and Firmicutes at phylum-level. In direct sediment samples Proteobacteria, whereas in pre-enriched sediment samples Firmicutes and Proteobacteria were determined at highest level. Pre-enriched fish samples were dominated by Proteobacteria and Firmicutes at phylum-level. In this study, microbiota members of Lake Van were identified by taxonomic analysis.