Gut microorganisms are comprised of thousands of species and play an important role in the host's metabolism, overall health status, and risk of disease. Recently, the discovery of non-photosynthetic ...cyanobacteria (class "Melainabacteria") in the human and animal gut triggered a broad interest in studying cyanobacteria's evolution, physiology, and ecological relevance of the Melainabacteria members. In the present paper, we review the general characteristics of Melainabacteria, their phylogeny, distribution, and ecology. The potential link between these microorganisms and human health is also discussed based on available human-microbiome studies. Their abundance tends to increase in patients with selected neurodegenerative, gastrointestinal, hepatic, metabolic, and respiratory diseases. However, the available evidence is correlative and requires further longitudinal studies. Although the research on Melainabacteria in the human gut is still in its infancy, elucidation of their role appears important in better understanding microbiome-human health interactions. Further studies aiming to identify particular gut cyanobacteria species, culture them
, and characterize them on the molecular, biochemical, and physiological levels are encouraged.
Summary
Microcystis is a cosmopolitan genus of cyanobacteria and occurs in many different forms. Large surface blooms of the cyanobacterium are well known in eutrophic lakes throughout the globe. We ...evaluated the role of microcystins (MCs) in promoting and maintaining bloom‐forming cell aggregates at environmentally relevant MC concentrations (0.25–10 µg l−1). MCs significantly enhanced Microcystis colony sizes. Colonial diameters in microcystin‐RR (MC‐RR)‐treated cultures (at 1 µg l−1) were significantly larger than control colonies, by factors of 1.5, 2.6 and 2.7 in Microcystis wesenbergii DC‐M1, M. ichthyoblabe TH‐M1 and Microcystis sp. FACHB1027 respectively. Depletion of extracellular MC concentrations caused Microcystis colony size to decrease, suggesting that released MCs are intimately involved in the maintenance of Microcystis colonial size. MC‐RR exposure did not influence Microcystis growth rate, but did significantly increase the production of extracellular polysaccharides (EPS). In addition, MC‐RR exposure appeared to trigger upregulation of certain parts of four polysaccharide biosynthesis‐related genes: capD, csaB, tagH and epsL. These results strongly indicate that induction of polysaccharides by MC‐RR was the major mechanism through which MCs enhanced colony formation in Microcystis spp. Cellular release of MCs, therefore, may play a key role in the persistence of algal colonies and the dominance of Microcystis.
In fault-bounded lacustrine basins, the lake basement may be exposed due to tilting of crustal blocks, forming islands of varying size. Such islands are commonly associated with sandy facies that may ...serve as important reservoirs for oil and gas accumulation. The present study investigated large sand bodies of Pleistocene-Holocene age on Songmenshan Island in the center of Poyang Lake, Jiangxi Province, southern China. The relationship of sedimentation on Songmenshan Island to its formation history was analyzed by means of Google satellite observations and field studies combined with scanning electron microscope, grain size, and
14
C dating analyses. The area of Songmenshan Island (39 km
2
) represents 8% of the total lake area (500 km
2
), and its height (81 m) is several times greater than that of the depth of the surrounding lake (13 m). The island has been uplifted since ~ 5 Ma at a rate of ~ 16 m Myr
− 1
as a consequence of intrabasinal block faulting. The surficial deposits of the island consist of wave-controlled beach-bars in the lower part (< 36 m elevation) and wind-controlled eolian dunes in the upper part. Sedimentary characteristics were different between beach bars and sand dunes in terms of bedding, sedimentary structures, and grain size and texture. The beach bars are characterized by low-angle cross-bedding, fan-shaped conchoidal, and disciform fractures, and small V-shaped impact craters on quartz grain surfaces. The eolian dunes are characterized by large-scale high-angle cross-bedding, dish-, crescent-, and V-shaped impact craters on quartz grain surfaces. Whereas sand movement in the beach-bar facies was dominantly through traction, saltation was the major process in the eolian dune environment. The depositional history of Songmenshan Island can be divided into 3 stages: (1) deltaic sedimentation from the Ganjiang and Xiushui rivers, which are connected to the Yangtze River via a channel; (2) wave reworking of deltaic sediments in shoreline beach-bar facies after initial uplift; and (3) wind reworking of sands in eolian dune facies following further uplift. Later in its history, Songmenshan Island was reduced through wind and wave erosion into two subequal parts (19.6 km
2
and 19.8 km
2
), producing its present configuration. The large sand bodies comprising this island may eventually be buried in a cocoon of organic-rich lacustrine muds, yielding an exploration target. Songmenshan Island may thus serve as a model for development of sand-rich reservoir facies in fault-bounded lacustrine basins.
The lowermost member of the Paleocene Funing Formation, which is composed of bioturbated fluvial red beds, is extensively distributed throughout the Jinhu Depression, Subei Basin, East China. Despite ...its economic value as one of the most important oil-bearing reservoirs in the Subei Basin, the sedimentology, ichnology and paleoenvironment of this formation in the Jinhu Depression remain poorly understood. In this work, we investigated the ichnofossils and sedimentary facies, analyzed the ichnofacies and potential tracemakers and reconstructed the paleoenvironment of the Jinhu Depression based on cores from the lowermost member of the Paleocene Funing Formation. This formation contains a moderately diverse ichnofauna (9 ichnotaxa of the Scoyenia ichnofacies) that includes meniscate burrows (Taenidium barretti, Taenidium satanassi and Beaconites coronus), simple horizontal cylindrical burrows (Palaeophycus tubularis, Palaeophycus heberti and Planolites isp.), simple vertical or subvertical burrows (Skolithos linearis and Skolithos isp.) and plant root traces. The other complex branched and chambered burrows are left in open nomenclature. These ichnofossils are widespread throughout the three facies associations identified in this study: (1) ephemeral fluvial channel, (2) crevasse splay and (3) distal floodplain facies associations. Multiple lines of sedimentological and ichnological evidence, namely, the predominance of massive and upper flow regime structures, the occurrence of invertebrate burrows (e.g., Skolithos and Taenidium) in the lower and middle parts of the channel deposits and the dramatic changes in the color and mottling in channel and overbank sediments, indicate that the river discharge was short lived and that the water table was highly variable. The variations in the discharge and water level are attributed to the influence of seasonal rainfall. The cyclic nature of intense rainfall events and dry periods suggests that the Subei Basin was likely located in a semiarid region with a seasonal rainfall pattern during the early Paleocene. This study also reveals that the ephemeral fluvial channel is the facies association with the highest potential to yield oil-bearing reservoirs in the Paleocene red beds of the Jinhu Depression. Additionally, the influence of bioturbation on the reservoir quality in this region should be considered in future research.
•Early Paleocene bioturbated red beds in the Jinhu Depression, Subei Basin, are of ephemeral fluvial origin.•A moderately diverse invertebrate ichnofauna (9 ichnotaxa of the Scoyenia ichnofacies) is identified.•Three facies associations with poorly distinctive trace fossil assemblages are interpreted.•River discharge was ephemeral, and the water table was variable.•Semiarid regional climate conditions accompanied by a seasonal rainfall pattern are suggested.
Background
Western Lake Erie is suffering from harmful cyanobacterial blooms, primarily toxic
Microcystis
spp., affecting the ecosystem, water safety, and the regional economy. Continued bloom ...occurrence has raised concerns about public health implications. However, there has been no investigation regarding the potential increase of
Legionella
and antibiotic resistance genes in source water, and disinfection byproducts in municipal treated drinking water caused by these bloom events.
Methods
Over 2 years, source water (total
n
= 118) and finished water (total
n
= 118) samples were collected from drinking water plants situated in western Lake Erie (bloom site) and central Lake Erie (control site). Bloom-related parameters were determined, such as microcystin (MC), toxic
Microcystis
, total organic carbon, N, and P. Disinfection byproducts (DBPs) total trihalomethanes (THMs) and haloacetic acids (HAAs) were assessed in finished water. Genetic markers for
Legionella
, antibiotic resistance genes, and mobile genetic elements were quantified in source and finished waters.
Results
Significantly higher levels of MC-producing
Microcystis
were observed in the western Lake Erie site compared to the control site. Analysis of DBPs revealed significantly elevated THMs concentrations at the bloom site, while HAAs concentrations remained similar between the two sites.
Legionella
spp. levels were significantly higher in the bloom site, showing a significant relationship with total cyanobacteria. Abundance of ARGs (
tet
Q and
sul
1) and mobile genetic elements (MGEs) were also significantly higher at the bloom site.
Discussion
Although overall abundance decreased in finished water, relative abundance of ARGs and MGE among total bacteria increased after treatment, particularly at the bloom site. The findings underscore the need for ongoing efforts to mitigate bloom frequency and intensity in the lake. Moreover, optimizing water treatment processes during bloom episodes is crucial to maintain water quality. The associations observed between bloom conditions, ARGs, and
Legionella
, necessitate future investigations into the potential enhancement of antibiotic-resistant bacteria and
Legionella
spp. due to blooms, both in lake environments and drinking water distribution systems.
We present an innovative concept of a screening tool for detecting free microcystin in cyanobacteria using a sandwich immunodetection format, based on Michael addition reaction between ...α,β-unsaturated carbonyl moiety of microcystin and thiol of coating substance. This proof-of-concept immunoassay was developed using bovine serum albumin as a microcystin-binding model, and was tested with toxic Microcystis samples. The preliminary results indicate that the proposed Michael addition-based immunodetection is promising and can be used as a platform for further development to become a useful tool for free microcystin analysis in various samples in the future.
The Shanganning Carbonate Platform (SCP) of the North China Craton (NCC) was located in the Trade Winds belt during the Cambrian, which influenced its facies development. In recent years, numerous ...drillcores have been recovered from these units, but the depositional environments and facies architecture of this large (~2.0 × 105 km2) carbonate platform system have not yet been reported in detail. In this study, we integrate sedimentological and magnetic fabric data collected from outcrops and drillcores in order to document variation in microfacies and facies associations within the SCP, to infer paleowind directions and constrain the paleogeographic location of the SCP, and to evaluate eolian controls on platform development. This analysis documented numerous carbonate microfacies belonging to six fabric types (mudstone, wackestone, packstone, grainstone, framestone, and dolostone) along with rarer siliciclastic sediments. These microfacies belong to facies associations representing tidal flat, open platform, platform margin, slope, and deep basinal depositional environments. Anisotropy of magnetic susceptibility (AMS) measurements yielded mean paleocurrent directions for the Early, Middle, and Late Cambrian of 114°, 63°, and 83° (± ~30°) from paleo-north, respectively, that were relatively consistent for 12 out of 13 platform-margin sites, all vectors being corrected for a post-Cambrian ~150° clockwise rotation of the NCC. These wind orientations are consistent with the SCP shifting from south of the paleo-Equator in the Early Cambrian to north of it by the Middle Cambrian. Paleo-Trade Winds influenced facies patterns across the platform, producing a distinct windward-leeward zonation. The windward margin is characterized by well-sorted oolitic grainstone, as well as (favositids) coral and (dasycladacean) algal-sponge framestone, and the leeward margin by poorly-sorted oolitic wackestone-grainstone and fine bioclastic sediments. The present study is innovative in 1) integrating microfacies and AMS analyses in order to establish paleowind patterns and influences on an ancient carbonate platform, 2) documenting windward-leeward variation in quantifiable sediment properties across the SCP, and 3) constraining the paleo-hemispheric location of the NCC during the Cambrian.
•Analysis of microfacies and depositional environments of Cambrian in Ordos Basin•Quantitative measurements of sediment properties across the platform were documented.•Paleo-hemispheric location of North China Craton was constrained during Cambrian.•Paleo-Trade Winds influenced windward versus leeward facies zonation patterns.•An integrated methodology of magnetic anisotropy and standard petrographic data
The Triassic Jiucaiyuan Formation is a vital oil and gas exploration target in the eastern part of the Junggar Basin. In this work, cores, thin sections, particle sizes, and conventional physical ...properties were analyzed in order to understand the sedimentary characteristics and depositional model of the Jiucaiyuan Formation in the Beisantai Uplift and to clarify the factors controlling reservoir development. The results demonstrate that the Jiucaiyuan Formation can be divided into seven lithofacies, namely massive bedding gravel, massive bedding sandstone, trough bedding sandstone, plane bedding sandstone, wavy bedding sandstone, parallel bedding siltstone, and massive bedding mudstone. Braided river delta facies dominate the Jiucaiyuan Formation. Nine main subtypes of facies were observed: flood plain, braided channel above lake level, natural levees above lake level, braided channel under lake level, interdistributary bays, natural levees under lake level, mouth bars, prodelta mud, and beach bar. The braided channel under lake level, mouth bar, and beach bar reservoirs exhibited the best physical properties, with average porosities of 16.54%, 19.83%, and 20.41%, respectively, and average permeabilities of 3.43 mD, 9.91 mD, and 12.98 mD, respectively. The physical properties of reservoirs in the study area are mainly controlled by sedimentation. Braided channels under lake level, mouth bars, and beach bars are favorable facies for the development of high-quality reservoirs. The results of this study are expected to serve as a theoretical basis for further exploration and development of oil and gas in the study area.
The Tarim Block is an ancient plate with a basement of ancient continental crust, which has been separated from the Rodinia supercontinent since the Neoproterozoic. During the Neoproterozoic, which ...lasted nearly 500 Myr, this block experienced significant evolutionary processes, such as proliferation, radioactive decay of elements, and gradual cooling and solidification. The investigation of Neoproterozoic paleogeography may shed light on the evolution of these geological events. In order to realize this potential, this study aimed to infer paleowind directions over the Tarim Block during each epoch of the Cryogenian–Ediacaran and to constrain the paleogeographic location of the Tarim Block. To this end, outcrop magnetic fabric data were employed to analyze the anisotropy of magnetic susceptibility within the Tarim Block. The anisotropy of magnetic susceptibility measurements yielded mean paleowind directions of 308° ± 69°, 277° ± 78°, and 256° ± 76° from the present north for the Early, Middle, and Late Cryogenian, respectively; the corresponding values for the Early and Late Ediacaran were 237° ± 77° and 254° ± 73° from the present north, respectively. Considering the rotation relationship of the Tarim Block from the Neoproterozoic to the present, the paleowind directions during the Early, Middle, and Late Cryogenian were ~55°, ~35°, and ~35° from the paleo-north, respectively. The paleowind directions during the Early and Late Ediacaran were ~35° and ~60° from paleo-north, respectively. By referring to the correspondence between the paleowind directions over the Tarim Block and trade winds in the Northern Hemisphere, this study provides evidence for the location of the Tarim Block during the Cryogenian–Ediacaran. The main contributions of this study can be summarized as follows: (1) paleowind patterns are established through the analysis of the anisotropy of magnetic susceptibility; (2) the paleogeographic location of the Tarim Block during the Cryogenian–Ediacaran is constrained; and (3) a reference for further study of the paleogeography of the Tarim Block during the Cryogenian–Ediacaran is provided.
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