The development and vertical distribution of populations of gas-vacuolate bacteria in a eutrophic,monomictic lake

The role of gas vacuoles in the vertical stratification of planktonic bacteria is analysed. Measurements made with certain gas-vacuolate bacteria in laboratory culture suggest that only colonial forms could sink or float fast enough to form population maxima in lakes by vertical migration from other depths. It is suggested that in the case of individual cells the importance of the buoyancy provided by gas vacuoles is to minimise sinking rates and thereby to increase residence times of the organisms at depths where conditions support their growth.Changes in the vertical distribution of a number of gas-vacuolate bacteria were followed throughout the year in a monomictic, eutrophic lake (Crose Mere, Shropshire). All were restricted to the anaerobic hypolimnion which developed in summer. The various species formed maxima at different depths and times. With some of them (e.g. species of Thiopedia, Pelonema and Brachyarcus) growth was necessary to explain their development. In others (e. g. species of Pelodictyon and two colourless bacteria) vertical migrations might also have contributed to their development.     

Distribution of iron- and manganese-oxidizing bacteria in the bottom sediments of Lake Baikal

The specific features of the distribution, abundance, and taxonomic diversity of bacteria oxidizing iron and manganese in the bottom sediments sampled from different areas of Lake Baikal are studied. These bacteria are widespread in Baikal bottom sediments. Cultivated iron- and manganese-oxidizing microorganisms are ascribed to six genera: Metallogenium, Leptothrix, Siderocapsa, Naumaniella, Bacillus, and Pseudomonas. The surface layers of the ground and the border between oxidized and reduced sediments serve as ecological niches for iron- and manganese-oxidizing microorganisms. Redox conditions of the environment and the availability of dissolved forms of iron and manganese, as well as of organic matter, which are controlled by the conditions of sedimentation in the lake, are the main factors affecting the abundance and distribution of iron bacteria.     

Benthic phototrophic community from Kiran soda lake,south-eastern Siberia

Phototrophic bacterial mats from Kiran soda lake (south-eastern Siberia) were studied using integrated approach including analysis of the ion composition of water, pigments composition, bacterial diversity and the vertical distribution of phototrophic microorganisms in the mats. Bacterial diversity was investigated using microscopic examination, 16S rRNA gene Illumina sequencing and culturing methods. The mats were formed as a result of decomposition of sedimented planktonic microorganisms, among which cyanobacteria of the genus Arthrospira predominated. Cyanobacteria were the largest part of phototrophs in the mats, but anoxygenic phototrophs were significant fraction. The prevailing species of the anoxygenic phototrophic bacteria are typical for soda lakes. The mats harbored aerobic anoxygenic phototrophic bacteria, purple sulfur and non-sulfur bacteria, as well as new filamentous phototrophic Chloroflexi. New strains of Thiocapsa sp. Kir-1, Ectothiorhodospira sp. Kir-2 and Kir-4, Thiorhodospira sp. Kir-3 and novel phototrophic Chloroflexi bacterium Kir15-3F were isolated and identified.

     

Pelodictyon phaeoclathratiforme sp. nov., a new brown-colored member of the Chlorobiaceae forming net-like colonies

A new strain of the green sulfur bacteria was isolated from the monimolimnion of Buchensee (near Radolfzell, Lake Constance region, FRG). Single cells were rod-shaped, nonmotile and contained gas vacuoles. Typical net-like colonies were formed by ternary fission of the cells. As photosynthetic pigments bacteriochlorophylls a, e, isorenieratene and -isorenieratene were present. Sulfide, sulfur and thiosulfate were used as electron donors during anaerobic phototrophic growth. Besides carbon dioxide, acetate and propionate could serve as carbon sources under mixotrophic conditions in the light. Like all other members of the green sulfur bacteria, the new bacterium is strictly anaerobic and obligately phototrophic. The possession of gas vacuoles and the formation of net-like colonies and the guanine plus cytosine content of the DNA (47.9 mol% G+C) are typical characteristics of the genus Pelodictyon. Because of its photosynthetic pigments which differ from those of Pelodictyon clathratiforme, strain BU 1 represents a new species, P. Phaeoclathratiforme sp. nov.     

Vertical distributions of bacteria and algae in a steeply stratified humic lake under high grazing pressure from Daphnia longispina

The vertical distributions of bacteria and algae in a steeply stratified, highly humic lake were studied during three 24 h periods in summer. The highest bacterial and algal densities and biomasses were recorded in the anoxic hypolimnion. The bacterial biomass in the hypolimnion was composed mainly of photosynthetic green sulphur bacteria (Chlorobium) which occurred at very low light intensity (< 1.5 μmol m⁻² s⁻¹). The numbers and biomasses of bacteria, both in the epilimnion and hypolimnion, were mostly higher at night than during the day, indicating possible asynchrony between the production and loss of bacteria. Because of vertical migration, the diurnal vertical distribution of algae was more variable than that of bacteria. Particularly in July and August, when cryptomonads were abundant, the biomass of algae was much higher in the epilimnion during the day than at night. The flagellated chlorophytes, Chlamydomonas spp. and Scourfieldia cordiformis, stayed mainly in the upper hypolimnion close to the oxic-anoxic boundary zone where only a small proportion of Daphnia longispina was continuously present. Unpalatable Mallomonas chrysophytes with silicified plates and bristles, and small, presumably heterotrophic, flagellates stayed in the oxic epilimnion together with a dense (up to 300 ind l⁻¹) population of D. longispina. The results indicated that, besides the physical and chemical properties of the water column, grazing pressure by Daphnia longispina strongly affected the vertical distribution of microorganisms in this polyhumic lake.     

High-diversity biofilm for the oxidation of sulfide-containing effluents

In the present work, we describe for the first time the utilization of a complex microbial biofilm for the treatment of sulfide-containing effluents. A non-aerated packed-column reactor was inoculated with anoxic lake sediment and exposed to light. A biofilm developed in the column and showed a stable oxidation performance for several weeks. Microbial species composition was analyzed by microscopy, pigment analysis and a bacterial 16S rRNA gene clone library. Colorless sulfur bacteria, green algae and purple sulfur bacteria were observed microscopically. Pigment composition confirmed the presence of algae and purple sulfur bacteria. The clone library was dominated by alpha-Proteobacteria (mostly Rhodobacter group), followed by gamma-Proteobacteria (Chromatiaceae-like and Thiothrix-like aerobic sulfur oxidizers) and the Cytophaga-Flavobacterium-Bacteroides group. Plastid signatures from algae were also present and a few clones belonged to both the beta- (Rhodoferax sp., Thiobacillus sp.) and delta-Proteobacteria (Desulfocapsa sp.) and to the low G+C Gram-positive bacteria (Firmicutes group). The coexistence of aerobic, anaerobic, phototrophic and chemotrophic microorganisms in the biofilm, the species richness found within these metabolic groups (42 operational taxonomic units) and the microdiversity observed within some species could be very important for the long-term functioning and versatility of the reactor.     

The Phototrophic Community Found in Lake Khilganta (an Alkaline Saline Lake Located in the Southeastern Transbaikal Region)

The structure of the phototrophic community found in Lake Khilganta (the Agin-Buryat Autonomous Area), a shallow saline soda lake (depth, 35–45 cm; water mineralization, 45 g/l; alkalinity, 30 mg-equiv/l; pH 9.5) has been studied. The bottom of the lake is covered with a 10- to 15-mm microbial mat, whose basis is formed by the filamentous cyanobacterium Microcoleus chthonoplastes. The mat exhibits pronounced layering and contains a significant amount of minerals. Six zones, which have characteristic colors and consistencies and are composed of intermittent layers, have been identified along the vertical profile. Live phototrophic bacteria have been found in the three upper zones. The bulk of the cyanobacteria is concentrated in the upper zone. In the lower zones, the development of purple bacteria has been observed. The diurnal dynamics of the vertical distribution of phototrophic microorganisms, which results from variations in the physicochemical environmental parameters, is described. Ectothiorhodospira sp. are dominant among the anoxyphotobacteria present. Their number, determined according to the inoculation method, is 10⁶–10⁷ cells/ml. The purple bacteria of the genera Allochromatium, Thiocapsa, and Rhodovulum are also present. Experiments with isolated pure cultures have shown that the anoxygenic photosynthetic bacteria of Lake Khilganta are halotolerant and alkalitolerant or alkaliphilic. In liquid enrichment cultures, at pH 9.5, the ratio of anoxyphotobacteria species is close to that observed in the lake. When the pH is increased to 10.4, it is Ectothiorhodospira, which is the most adapted to life under increased mineralization and alkalinity, that predominantly develops. Photosynthetic activity has been observed in the three upper mat zones and constitutes, on average, 1.5 g C/(m²h); the share of anoxygenic photosynthesis accounts for 75–95% of the total productivity. The main role in sulfide oxidation belongs to the phototrophic anoxyphotobacteria and cyanobacteria. In terms of the physicochemical conditions and structure of the phototrophic community, Lake Khilganta is similar to shallow saline water bodies of marine origin. The main differences consist in the increased alkalinity and in the consequent prevalence of alkaliphilic and alkalitolerant microorganisms and in the absence of representatives of the neutrophilic group of green sulfur bacteria.__________Translated from Mikrobiologiya, Vol. 74, No. 3, 2005, pp. 410–419.Original Russian Text Copyright © 2005 by Kompantseva, Sorokin, Gorlenko, Namsaraev.     

Halobacterial Community Analysis of Mierlei Saline Lake in Transylvania (Romania)

In this study a combination of both molecular and biochemical methods have been used to characterize the bacterial microbiota in water and sediment of a saline lake in Transylvania. The physicochemical characterization of the water samples from different lake depths indicated a stratification of the lake that affects the distribution of resident microorganisms, confirmed also by the significant differences in terms of functional diversity of the microbial communities in different water layers. The superficial bacterial community shows a good oxidative capability, degrading a wide range of organic substrates, yet the bottom layer community exhibits a major level of specialization. The membrane fatty acid analysis of the sediment bacterial community shows the prevalent presence of Gram negative bacteria, confirmed by the culturing techniques. Among the 24 collected isolates, 16S rRNA gene sequencing analysis permitted to identify 10 different species, belonging to Bacillus, Halomonas, Idiomarina, Marinobacter, Pseudoalteromonas, Salinivibrio, Staphylococcus genera and prevalently classified as halophiles.     

Vertical distribution and diel migration of flagellated phytoplankton in a small humic lake

The vertical distributions and migrations are described of the most abundant flagellated phytoplankton species from the summer community of a small forest lake in southern Finland. The lake showed a steep and stable thermal stratification with a shallow oxygenated epilimnion. Horizontal variation of phytoplankton distribution within the lake was tested on two scales and found to be statistically significant only in the case of Mallomonas reginae. The vertical distribution of flagellated phytoplankton was assessed by reference to the distribution of a non-motile, neutrally buoyant species Ankyra judayi. Statistically significant, active vertical positioning was demonstrated for all the flagellates examined with the exception of Spiniferomonas bourrellyi. Diel vertical migrations were apparent for all species showing active positioning and the pattern of an evening descent and a morning ascent was ubiquitous. The extent and timing of diel migrations varied between species. The most extensive migrations were by Cryptomonas marssonii which crossed a temperature gradient of 14 °C and penetrated far into the anoxic hypolimnion. Several categories of competitive advantage can be gained by species undertaking such diel vertical migrations.     

安徽省某酸性矿山废水坑湖中细菌群落的垂向分布特征及其影响因素

【目的】探究酸性矿山废水(acid mine drainage,AMD)坑湖中细菌群落沿垂向不同水深的分布规律及与环境因子之间的相互作用。【方法】采用16SrRNA基因高通量测序技术,对安徽省某AMD坑湖中6条采样垂线不同水深深度的细菌群落进行调查,同时测定水质理化指标,使用统计学软件分析细菌和地化参数间的联系。【结果】AMD坑湖中水质特征及细菌群落结构出现明显分层现象,自上而下溶解氧降低而pH和多种金属离子浓度增加,微生物群落结构发生变化,多样性和部分物种的丰度增大。细菌群落组成上,表层水域以Proteobacteria (Alpha、Gammaproteobacteria)和Acidobacteria占据主导地位;中下层水域则由Firmicutes、Acidobacteria、Actinobacteria、Gammaproteobacteria和Patescibacteria等共同主导。统计分析结果表明,TN、DO、ORP、pH、Fe、Mn、Al和Zn与嗜酸细菌丰度显著相关,是细菌空间分布的主要限制因素。【结论】AMD坑湖中水质理化特征和细菌群落分布在垂向空间上存在显著差异,群落的...     

Distribution of Heterotrophic Bacteria in Lake Shira

A study of the horizontal and vertical distribution of heterotrophic bacteria in brackish Lake Shira in summer periods showed that mesophilic bacteria dominated in all areas of the lake, whereas psychrotolerant bacteria dominated in the metalimnion and hypolimnion of its central part. Nonhalophilic bacteria were mostly mesophilic and dominated in coastal waters. Most psychrotolerant bacteria were able to grow in the presence of 5–10% NaCl. Heterotrophic bacteria isolated in different regions of the lake were identified to a generic level. The isolates were classified into autochthonous and allochthonous microorganisms on the bases of their distribution pattern in the lake water, halotolerance, and ability to grow at low temperatures.     

运城盐湖细菌群落结构及生态多样性分析

运城盐湖作为一个人类活动深入参与的高盐环境,其中的细菌群落结构及生态多样性既有盐湖环境的共性,又有自身的特殊性。【目的】运城盐湖湖水颜色丰富,蕴含着大量嗜盐及耐盐微生物资源。为了深入探究运城盐湖细菌资源分布规律,对不同水域中细菌多样性和群落结构进行研究,探讨运城盐湖不同水域中细菌群落结构的变化规律。【方法】基于16S rRNA基因的扩增子高通量测序,对运城盐湖不同水域的细菌群落结构进行分析,同时对微生物的潜在代谢功能进行预测。【结果】运城盐湖不同水域中的优势细菌类群有所差异,在盐湖中部,假单胞菌门(Pseudomonadota)、放线菌门(Actinobacteriota)和拟杆菌门(Bacteroidota)是优势类群;而在运城盐湖东部,芽孢杆菌门(Bacillota)则是主要类群;在运城盐湖西部,髌骨菌门(Patescibacteria)类群较为丰富。对运城盐湖不同区域的细菌多样性进行分析,数据显示盐湖中部浅黄色湖水中微生物多样性显著高于盐湖东部和西部区域,但盐湖中部红色湖水区域的微生物多样性较低。另外,在盐湖中部,湖水颜色不同的区域细菌物种分布也具有较大的差异。对运城盐湖细菌代谢功能进行预测分析发现,在盐湖不同区域的微生物参与的代谢通路活性各不相同,表现出较强的区域分布性,盐湖东部和西部的微生物代谢比盐湖中部更具有活性。【结论】运城盐湖微生物多样性丰富,不同水域的细菌多样性具有显著差异,盐湖不同水域的环境对细菌群落结构具有一定影响。本研究为运城盐湖细菌资源多样性的保育及开发利用提供了重要的理论基础。     

Effect of biostimulation on the microbial community in PCB-contaminated sediments through periodic amendment of sediment with iron

Reductive dehalogenation of polychlorinated biphenyls (PCBs) by indigenous dehalorespiring microorganisms in contaminated sediments may be enhanced via biostimulation by supplying hydrogen generated through the anaerobic corrosion of elemental iron added to the sediment. In this study, the effect of periodic amendment of sediment with various dosages of iron on the microbial community present in sediment was investigated using phospholipid fatty acid analysis (PLFA) over a period of 18 months. Three PCB-contaminated sediments (two freshwater lake sediments and one marine sediment) were used. Signature biomarker analysis of the microbial community present in all three sediments revealed the enrichment of Dehalococcoides species, the population of which was sustained for a longer period of time when the sediment microcosms were amended with the lower dosage of iron (0.01 g iron per g dry sediment) every 6 months as compared to the blank system (without iron). Lower microbial stress levels were reported for the system periodically amended with 0.01 g of iron per g dry sediment every 6 months, thus reducing the competition from other hydrogen-utilizing microorganisms like methanogens, iron reducers, and sulfate reducers. The concentration of hydrogen in the system was found to be an important factor influencing the shift in microbial communities in all sediments with time. Periodic amendment of sediment with larger dosages of iron every 3 months resulted in the early prevalence of Geobacteraceae and sulfate-reducing bacteria followed by methanogens. An average pH of 8.4 (range of 8.2–8.6) and an average hydrogen concentration of 0.75% (range of 0.3–1.2%) observed between 6 and 15 months of the study were found to be conducive to sustaining the population of Dehalococcoides species in the three sediments amended with 0.01 g iron per g dry sediment. Biostimulation of indigenous PCB dechlorinators by the periodic amendment of contaminated sediments with low dosages of iron metal may therefore be an effective technology for remediation of PCB-contaminated sediments.     

Temporal changes and vertical distribution of macrophytes in Lake Kawaguchi

 The distribution of macrophytes in Lake Kawaguchi, Japan, was surveyed in August 1999 using a sampling anchor from a boat. The survey revealed that the present aquatic vegetation was composed of 17 submerged species, and no floating-leaved plants were present. The diversity of submerged plants and their vertical growth limits decreased progressively from the west to the east end of the lake. At the time of the survey, the dominant species was Elodea nuttallii (Planch.) St. John, which had once grown explosively in the mid-1980s in the lake, and except for Vallisneria asiatica Miki, all of the species commonly observed in the lake seem to have diminished their growth greatly. Among them, Potamogeton compressus L., which was the most dominant species in the lake before the invasion of Elodea nuttallii, had decreased most severely. It is suggested that the present state of aquatic vegetation in this lake was much influenced by the persistent growth of Elodea nuttallii as well as by environmental factors. Received: August 7, 2001 / Accepted: February 9, 2002     

Identification of Sulfur-Cycle Prokaryotes in a Low-Sulfate Lake (Lake Pavin) Using <Emphasis Type="Italic">aprA</Emphasis> and 16S rRNA Gene Markers

Geochemical researches at Lake Pavin, a low-sulfate-containing freshwater lake, suggest that the dominant biogeochemical processes are iron and sulfate reduction, and methanogenesis. Although the sulfur cycle is one of the main active element cycles in this lake, little is known about the sulfate-reducer and sulfur-oxidizing bacteria. The aim of this study was to assess the vertical distribution of these microbes and their diversities and to test the hypothesis suggesting that only few SRP populations are involved in dissimilatory sulfate reduction and that Epsilonproteobacteria are the likely key players in the oxidative phase of sulfur cycle by using a PCR aprA gene-based approach in comparison with a 16S rRNA gene-based analysis. The results support this hypothesis. Finally, this preliminary work points strongly the likelihood of novel metabolic processes upon the availability of sulfate and other electron acceptors.     

Legionella clemsonensis sp. nov.: a green fluorescing Legionella strain from a patient with pneumonia

A novel Legionella species was identified based on sequencing, cellular fatty acid analysis, biochemical reactions, and biofilm characterization. Strain D5610 was originally isolated from the bronchial wash of a patient in Ohio, USA. The bacteria were gram‐negative, rod‐shaped, and exhibited green fluorescence under long wave UV light. Phylogenetic analysis and fatty acid composition revealed a distinct separation within the genus. The strain grows between 26–45°C and forms biofilms equivalent to L. pneumophila Philadelphia 1. These characteristics suggest that this isolate is a novel Legionella species, for which the name Legionella clemsonensis sp nov. is proposed.     

Distribution of Parthenogenesis-Inducing Symbionts in Ovaries and Eggs of Aphytis (Hymenoptera: Aphelinidae)

In parasitic Hymenoptera, severe sex ratio distortions are sometimes associated with the presence of symbiotic microorganisms. Symbiont-induced uniparental reproduction is found in several species of the genus Aphytis and is suspected in others. These intracellular bacteria (called Wolbachia) reside within the egg cytoplasm. In order to follow their vertical transmission, the distribution pattern of the symbionts in ovaries and eggs of two uniparental lines (A. lingnanensis and A. yanonensis) was studied by electron, confocal, and two-photon microscopy. The results obtained suggest that Wolbachia move from nurse cells to developing oocytes. In freshly laid eggs, the symbionts are concentrated in the posterior pole, away from the micropyle, and in later stages of embryogenesis they are found surrounding nuclei throughout the embryo. Received: 20 May 1997 / Accepted: 25 June 1997     

TAXONOMIC STUDY OF TWO NEW GENERA OF FUSIFORM GREEN FLAGELLATES,TABRIS GEN. NOV. AND HAMAKKO GEN. NOV. (VOLVOCALES,CHLOROPHYCEAE)1

On the basis of LM, we isolated strains of two species of fusiform green flagellates that could be assigned to former Chlorogonium (Cg.) Ehrenb. One species, “Cg.”heimii Bourr., lacked a pyrenoid in its vegetative cells and required organic compounds for growth. The other was similar to Cg. elongatum (P. A. Dang.) Francé and “Cg.”acus Nayal, but with slightly smaller vegetative cells. Their molecular phylogeny was also studied based on combined 18S rRNA, RUBISCO LSU (rbcL), and P700 chl a‐apoprotein A2 (psaB) gene sequences. Both species were separated from Chlorogonium emend., Gungnir Nakada and Rusalka Nakada, which were formerly assigned to Chlorogonium. They were accordingly assigned to new genera, Tabris Nakada gen. nov. and Hamakko (Hk.) Nakada gen. nov. as T. heimii (Bourr.) Nakada comb. nov. and Hk. caudatus Nakada sp. nov., respectively. Tabris is differentiated from other genera of fusiform green flagellates by its vegetative cells, which only have two apical contractile vacuoles and lack a pyrenoid in the chloroplast. Hamakko, on the other hand, is distinguishable by the fact that its pyrenoids in vegetative cells are penetrated by flattened thylakoid lamellae.     

Corrosion behavior of carbon steel in the presence of two novel iron-oxidizing bacteria isolated from sewage treatment plants

In this work, two novel iron oxidizing bacteria (IOB), namely Gordonia sp. MZ-89 and Enterobacter sp. M01101, were isolated from sewage treatment plants and identified by biochemical and molecular methods. Then, microbially influenced corrosion (MIC) of carbon steel in the presence of these bacteria was investigated. The electrochemical techniques such as potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS) were used to measure the corrosion rate and observe the corrosion mechanism. The results showed that the existence of these microorganisms decreased the corrosion potential and enhanced the corrosion rate. Scanning electron microscopy (SEM) images revealed the ground boundary attacks and pitting on carbon steel samples in the presence of these bacteria after polarization. Corrosion scales were identified with X-ray diffraction (XRD). It was demonstrated that these bacteria can greatly affect the crystalline phase of corrosion products that also confirmed by SEM results. It was inferred that these bacteria were responsible for the corrosion of carbon steel, especially in the form of localized corrosion.     

Microbial communities of the stratified soda Lake Doroninskoe (Transbaikal region)

The physicochemical properties, species composition, and vertical distribution of microorganisms in the water column, shoreline microbial mat, and small shoreline mud volcanoes of the stratified soda Lake Doroninskoe were investigated in September 2007. The lake is located in the Transbaikal region, in the permafrost zone (51°25′N; 112°28′E). The maximal depth of the contemporary lake is about 6 m, the pH value of the water is 9.72, and the water mineralization in the near-bottom horizon is 32.3 g l⁻¹. In summer, the surface oxygen-containing horizon of the water column becomes demineralized to 26.5 g l⁻¹; at a depth of 3.5–4.0 m, an abrupt transition occurs to the aerobic zone containing hydrosulfide (up to 12.56 g l⁻¹). Hydrosulfide was also detected in trace quantities in the upper water horizons. The density stratification of the water column usually ensures stable anaerobic conditions until the freezing period (November and December). The primary production of oxygenic phototrophs reached 176–230 μg l⁻¹. High rates of dark CO₂ assimilation (61–240 μg l⁻¹) were detected in the chemocline. Within this zone, an alkaliphilic species of sulfur-oxidizing bacteria of the genus Thioalkalivibrio was detected (10⁴ cells ml⁻¹). Lithoheterotrophic bacteria Halomonas spp., as well as bacteriochlorophyll a-containing aerobic anoxygenic phototrophic bacteria (AAP) Roseinatronobacter sp. capable of thiosulfate oxidation, were isolated from samples collected from the aerobic zone (0–3 m). The water transparency in September was extremely low; therefore, no visible clusters of anoxygenic phototrophic bacteria (APBs) were detected at the boundary of the hydrosulfide layer. However, purple sulfur bacteria which, according to the results of the 16S rRNA gene analysis, belong to the species Thioalkalicoccus limnaeus, Ectothiorhodospira variabilis, “Ect. magna,” and Ect. shaposhnikovii, were isolated from samples of deep silt sediments. Ect. variabilis and Ect. shaposhnikovii were the major APB species in the shoreline algo-bacterial mat. The halotolerant bacterium Ect. shaposhnikovii, purple nonsulfur bacteria of the genus Rhodobacter, and AAP of Roseococcus sp. were isolated from the samples collected from mud volcanoes. All these species are alkaliphiles, moderate halophiles, or halotolerant microorganisms.