Uncovering the microbial community structure and physiological profiles of terrestrial mud volcanoes: A comprehensive metagenomic insight towards their trichloroethylene biodegradation potentiality.

Mud volcanoes are dynamic geological features releasing methane (CH4), carbon dioxide (CO2), and hydrocarbons, harboring diverse methane and hydrocarbon-degrading microbes. However, the potential application of these microbial communities in chlorinated hydrocarbons bioremediation purposes such as trichloroethylene (TCE) has not yet been explored. Hence, this study investigated the mud volcano's microbial diversity functional potentiality in TCE degradation as well as their eco-physiological profiling using metabolic activity. Geochemical analysis of the mud volcano samples revealed variations in pH, temperature, and oxidation-reduction potential, indicating diverse environmental conditions. The Biolog Ecoplate™ carbon substrates utilization pattern showed that the Tween 80 was highly consumed by mud volcanic microbial community. Similarly, MicroResp® analysis results demonstrated that presence of additive C-substrates condition might enhanced the cellular respiration process within mud-volcanic microbial community. Full-length 16 S rRNA sequencing identified Proteobacteria as the dominant phylum, with genera like Pseudomonas and Hydrogenophaga associated with chloroalkane degradation, and methanotrophic bacteria such as Methylomicrobium and Methylophaga linked to methane oxidation. Functional analysis uncovered diverse metabolic functions, including sulfur and methane metabolism and hydrocarbon degradation, with specific genes involved in methane oxidation and sulfur metabolism. These findings provide insights into the microbial diversity and metabolic capabilities of mud volcano ecosystems, which could facilitate their effective application in the bioremediation of chlorinated compounds.

Methanogen activity and microbial diversity in Gulf of Cádiz mud volcano sediments.

The Gulf of Cádiz is a tectonically active continental margin with over sixty mud volcanoes (MV) documented, some associated with active methane (CH4) seepage. However, the role of prokaryotes in influencing this CH4 release is largely unknown. In two expeditions (MSM1-3 and JC10) seven Gulf of Cádiz MVs (Porto, Bonjardim, Carlos Ribeiro, Captain Arutyunov, Darwin, Meknes, and Mercator) were analyzed for microbial diversity, geochemistry, and methanogenic activity, plus substrate amended slurries also measured potential methanogenesis and anaerobic oxidation of methane (AOM). Prokaryotic populations and activities were variable in these MV sediments reflecting the geochemical heterogeneity within and between them. There were also marked differences between many MV and their reference sites. Overall direct cell numbers below the SMTZ (0.2-0.5 mbsf) were much lower than the general global depth distribution and equivalent to cell numbers from below 100 mbsf. Methanogenesis from methyl compounds, especially methylamine, were much higher than the usually dominant substrates H2/CO2 or acetate. Also, CH4 production occurred in 50% of methylated substrate slurries and only methylotrophic CH4 production occurred at all seven MV sites. These slurries were dominated by Methanococcoides methanogens (resulting in pure cultures), and prokaryotes found in other MV sediments. AOM occurred in some slurries, particularly, those from Captain Arutyunov, Mercator and Carlos Ribeiro MVs. Archaeal diversity at MV sites showed the presence of both methanogens and ANME (Methanosarcinales, Methanococcoides, and ANME-1) related sequences, and bacterial diversity was higher than archaeal diversity, dominated by members of the Atribacterota, Chloroflexota, Pseudomonadota, Planctomycetota, Bacillota, and Ca. "Aminicenantes." Further work is essential to determine the full contribution of Gulf of Cádiz mud volcanoes to the global methane and carbon cycles.

Seasonal variations of geofluids from mud volcano systems in the Southern Junggar Basin, NW China.

Variations in the chemical composition of geofluids and of gas fluxes are significant parameters for understanding mud volcanism and correctly estimate their emissions in carbon species, particularly greenhouse gas, methane. In this study, muddy water and gas samples were collected from the Anjihai, Dushanzi, Aiqigou, and Baiyanggou mud volcanoes in the southern Junggar Basin during the four seasons, around a year. This region hosts the most active mud volcanism throughout China. Gas and water were analyzed for major molecular compositions, carbon and hydrogen isotopes of the gas phase, as well as cations and anions, hydrogen and oxygen isotopes of water. The emitted gases are dominated by CH4 with some C2H6, CO2, and N2. The seasonal changes in the chemical composition and carbon isotopes of emitted gases are not significant, whereas clear variations in the amounts of cations and anions dissolved in the water are reported. These are higher in spring and summer than autumn and winter. The CH4, CO2, and C2H6 fluxes are 157.3-1108 kg/a, 1.8-390.1 kg/a, and 10.2-118.7 kg/a, respectively, and a clear seasonal trend of the gas seepage flux has been observed. In January, the macro-seepage flux of open vents is ≥65 % higher than in April, whereas the micro-seepage flux significantly decreased, probably due to the frozen shallow ground and blockage of soil fractures around the vents by heavy snow and ice during January. This probably causes an extra gas pressure transferred to the major vents, resulting in higher flux of the macro-seepage in the cold season. However, the total flux of the whole mud volcano system is generally consistent around a year.

Physical and geochemical characteristics of land mud volcanoes along Colombia's Caribbean coast and their societal impacts.

The Caribbean coast is characterized by the presence of mud volcanoes, a secondary phenomenon of volcanism similar to mud diapirs for its development and evolution, but different in terms of geological features and forms. These mud volcanoes are often located close to tectonic faults and oil and gas deposits. Their geological context is dominated by the presence of clay sediments and brackish water, that favors the decomposition of organic material and the formation of methane. Mud volcanoes can thus be an important reservoir of hydrocarbons. This paper aims to fill the existing gap in the knowledge of mud volcanoes (MVs) of Colombia. We analyze the physical and geochemical characteristics of nine onshore mud volcanoes located in the Departments of Atlántico (La Laguna), Bolívar (Las Palomas, La Bonga, Santa Catalina, Yerbabuena, Clemencia, and Membrillal), Cordóba (Los Olivos), and Magdalena (Cañaveral). These structures present a kaolinitic composition, except for La Laguna mud volcano in which smectite is predominant. Apart from tectonic processes, this influences the shape and size of MVs and, also, the type and frequency of eruptions. The abundance of methane in all sites confirms the thermogenic origin of these structures. MVs are often considered landscape attractions as well as a therapeutic resources, but unfortunately they also represent a serious risk for the local communities, due to the frequent unexpected, eruptions, sometimes accompanied by the release of toxic gases or by landslides, that can damage the infrastructures and hurt the population living in the area. The MVs are classified into five vulnerability classes using a novel synthetic index which could improve the understanding of risks associated with the presence of MVs in proximity to towns and infrastructures.

A chemical and microbial characterization of selected mud volcanoes in Trinidad reveals pathogens introduced by surface water and rain water.

Terrestrial mud volcanoes are unique structures driven by tectonic pressure and fluids from the deep subsurface. These structures are mainly found in active tectonic zones, such as the area near the Los Bajos Fault in Trinidad. Here we report a chemical and microbiological characterization of three mud volcanoes, which included analyses of multiple liquid and solid samples from the mud volcanoes. Our study confirms previous suggestions that at least some of the mud volcano fluids are a mixture of deeper salt-rich water and surficial/precipitation water. No apparent water quality differences were found between sampling sites north and south of a major geological fault line. Microbiological analyses revealed diverse communities, both aerobic and anaerobic, including sulfate reducers, methanogens, carbon dioxide fixing and denitrifying bacteria. Several identified species were halophilic and likely derived from the deeper salt-rich subsurface water, while we also cultivated pathogenic species from the Vibrionaceae, Enterobacteriaceae, Shewanellaceae, and Clostridiaceae. These microorganisms were likely introduced into the mud volcano fluids both from surface water or shallow ground-water, and perhaps to a more minor degree by rain water. The identified pathogens are a major health concern that needs to be addressed.

Rare earth elements in mud volcano sediments from the Gulf of Cadiz, South Iberian Peninsula.

Eight gravity cores (GC) were retrieved from the deep mud volcanoes Sagres, Bonjardim, Soloviev and Porto in the Gulf of Cadiz. Cores with 137 to 317 cm long were sliced in intervals of 15 to 20 cm thickness, and 46 samples were analyzed for grain size distribution, loss on ignition, Al, Fe, Ca, Mg, Mn, Sr, Ba and the rare earth elements (REE) La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu. REE profile normalized to Post-Archean Australian Average Shale (PAAS) was dominated by a mid-REE bulge with a pronounced Eu enhancement. Sediment reducing conditions resulting from the anaerobic oxidation of methane probably contributed to the positive-Eu anomaly (1.18-2.19, PAAS normalization). Most likely, reactions near the sulfate-methane transition zone such as the precipitation of barium sulfate found at layers around 50-cm depth explain the enhancement of Eu/Eu* ratios. The Ce anomalies (0.93-1.09) were almost absent.

Three species of Reteporella (Bryozoa: Cheilostomata) in a diapiric and mud volcano field of the Gulf of Cádiz, with the description of Reteporella victori n. sp.

Diapirs and mud volcanoes (MVs) are formed by the migration and extrusion of fluids and mud to the seafloor, respectively. In the Gulf of Cádiz there are ca. 60 MVs and several diapirs with different environmental conditions and seepage activity. Previous studies, mainly on MVs, have demonstrated that the invertebrate fauna associated with these seafloor structures can be very diverse, including chemosymbiotic species, mostly mollusks and frenulate polychaetes, as well as vulnerable suspension feeders, such as cold-water corals and sponges, among others. Previous studies of the bryozoan fauna in this area have recorded species belonging to 28 families. One of these families is Phidoloporidae, which comprises 27 genera worldwide, including the common Rhynchozoon, Reteporellina, and Reteporella. In the present study, two species belonging to Reteporella are redescribed, and a new species is described from diapirs and MVs on the shelf and slope of the Gulf of Cádiz. The samples were collected during several oceanographic expeditions carried out by the Instituto Español de Oceanografia. This genus is well represented in the NE Atlantic Ocean and the Mediterranean Sea, and our study extends its occurrence on MVs and diapirs fields of the Gulf of Cádiz.

Microbial biodiversity of Tang and Pirgal mud volcanoes and evaluation of bio-emulsifier and bio-demulsifier activities of Capnophile bacteria.

The data presented in this article is related to the Master thesis; entitled "Survey Aerobic Microbial Diversity Mud Volcanoes in Chabahar and Khash Ports in Southern Iran" by the first author of this article, year 2011, Islamic Azad University, Iran (reference number (Parsia, 2011) [1] of this article). This article shows microbial biodiversity and evaluates bio-emulsifier and bio-demulsifier abilities of capnophile isolates, in order to introduce a superior isolate for the Microbial Enhanced Oil Recovery (MEOR) process in the petrochemical industry.

The Apseudomorpha (Crustacea: Tanaidacea) of the Gulf of Cadiz and Horseshoe Continental Rise (NE Atlantic): A taxonomic review with new records, species, and ecological data.

The apseudomorphan tanaidaceans of the deep sea have been under-studied, especially in chemosynthetic habitats. A total of ten species present in the Gulf of Cadiz and the Horseshoe Continental Rise (SW off the Iberian Peninsula) are listed here, and new distribution data, ecological remarks and description of one new species of Atlantapseudes (Atlantapseudes curvatus sp. nov.) from recent research cruises are added. Pseudosphyrapus azorensis and Francapseudes uniarticulatus are recorded for the first time since the original descriptions. Notes on morphological development of Leviapseudes segonzaci and intraspecific variation of F. uniarticulatus are included, together with illustrations and descriptions of the material from the Gulf of Cadiz to complement previous descriptions.

Sedimentology and geochemistry of mud volcanoes in the Anaximander Mountain Region from the Eastern Mediterranean Sea.

Investigations carried out on surface sediments collected from the Anaximander mud volcanoes in the Eastern Mediterranean Sea to determine sedimentary and geochemical properties. The sediment grain size distribution and geochemical contents were determined by grain size analysis, organic carbon, carbonate contents and element analysis. The results of element contents were compared to background levels of Earth's crust. The factors that affect element distribution in sediments were calculated by the nine push core samples taken from the surface of mud volcanoes by the E/V Nautilus. The grain size of the samples varies from sand to sandy silt. Enrichment and Contamination factor analysis showed that these analyses can also be used to evaluate of deep sea environmental and source parameters. It is concluded that the biological and cold seep effects are the main drivers of surface sediment characteristics from the Anaximander mud volcanoes.

Linking geochemical processes in mud volcanoes with arsenic mobilization driven by organic matter.

The present study deals with geochemical characterization of mud fluids and sediments collected from Kunshuiping (KSP), Liyushan (LYS), Wushanting (WST), Sinyangnyuhu (SYNH), Hsiaokunshui (HKS) and Yenshuikeng (YSK) mud volcanoes in southwestern Taiwan. Chemical constituents (cations, anions, trace elements, organic carbon, humic acid, and stable isotopes) in both fluids and mud were analyzed to investigate the geochemical processes and spatial variability among the mud volcanoes under consideration. Analytical results suggested that the anoxic mud volcanic fluids are highly saline, implying connate water as the probable source. The isotopic signature indicated that δ(18)O-rich fluids may be associated with silicate and carbonate mineral released through water-rock interaction, along with dehydration of clay minerals. Considerable amounts of arsenic in mud irrespective of fluid composition suggested possible release through biogeochemical processes in the subsurface environment. Sequential extraction of As from the mud indicated that As was mostly present in organic and sulphidic phases, and adsorbed on amorphous Mn oxyhydroxides. Volcanic mud and fluids are rich in organic matter (in terms of organic carbon), and the presence of humic acid in mud has implications for the binding of arsenic. Functional groups of humic acid also showed variable sources of organic matter among the mud volcanoes being examined. Because arsenate concentration in the mud fluids was found to be independent from geochemical factors, it was considered that organic matter may induce arsenic mobilization through an adsorption/desorption mechanism with humic substances under reducing conditions. Organic matter therefore plays a significant role in the mobility of arsenic in mud volcanoes.