Mn2+ recycling in hypersaline wastewater: unnoticed intracellular biomineralization and pre-cultivation of immobilized bacteria.

Microbially induced manganese carbonate precipitation has been utilized for the treatment of wastewater containing manganese. In this study, Virgibacillus dokdonensis was used to remove manganese ions from an environment containing 5% NaCl. The results showed a significant decrease in carbonic anhydrase activity and concentrations of carbonate and bicarbonate ions with increasing manganese ion concentrations. However, the levels of humic acid analogues, polysaccharides, proteins, and DNA in EPS were significantly elevated compared to those in a manganese-free environment. The rhodochrosite exhibited a preferred growth orientation, abundant morphological features, organic elements including nitrogen, phosphorus, and sulfur, diverse protein secondary structures, as well as stable carbon isotopes displaying a stronger negative bias. The presence of manganese ions was found to enhance the levels of chemical bonds O-C=O and N-C=O in rhodochrosite. Additionally, manganese in rhodochrosite exhibited both + 2 and + 3 valence states. Rhodochrosite forms not only on the cell surface but also intracellularly. After being treated with free bacteria for 20 days, the removal efficiency of manganese ions ranged from 88.4 to 93.2%, and reached a remarkable 100% on the 10th day when using bacteria immobilized on activated carbon fiber that had been pre-cultured for three days. The removal efficiency of manganese ions was significantly enhanced under the action of pre-cultured immobilized bacteria compared to non-pre-cultured immobilized bacteria. This study contributes to a comprehensive understanding of the mineralization mechanism of rhodochrosite, thereby providing an economically and environmentally sustainable biological approach for treating wastewater containing manganese.

Effect of Ba2+ on the biomineralization of Ca2+ and Mg2+ ions induced by Bacillus licheniformis.

The effect of barium ions on the biomineralization of calcium and magnesium ions is often overlooked when utilizing microbial-induced carbonate precipitation technology for removing barium, calcium, and magnesium ions from oilfield wastewater. In this study, Bacillus licheniformis was used to bio-precipitate calcium, magnesium, and barium ions. The effects of barium ions on the physiological and biochemical characteristics of bacteria, as well as the components of extracellular polymers and mineral characteristics, were also studied in systems containing coexisting barium, calcium, and magnesium ions. The results show that the increasing concentrations of barium ions decreased pH, carbonic anhydrase activity, and concentrations of bicarbonate and carbonate ions, while it increased the contents of humic acids, proteins, polysaccharides, and DNA in extracellular polymers in the systems containing all three types of ions. With increasing concentrations of barium ions, the content of magnesium within magnesium-rich calcite and the size of minerals precipitated decreased, while the full width at half maximum of magnesium-rich calcite, the content of O-C=O and N-C=O, and the diversity of protein secondary structures in the minerals increased in systems containing all three coexisting ions. Barium ions does inhibit the precipitation of calcium and magnesium ions, but the immobilized bacteria can mitigate the inhibitory effect. The precipitation ratios of calcium, magnesium, and barium ions reached 81-94%, 68-82%, and 90-97%. This research provides insights into the formation of barium-enriched carbonate minerals and offers improvements for treating oilfield wastewater.

Co-removal and recycling of Ba2+ and Ca2+ in hypersaline wastewater based on the microbially induced carbonate precipitation technique: Overlooked Ba2+ in extracellular and intracellular vaterite.

This study investigates the co-precipitation of calcium and barium ions in hypersaline wastewater under the action of Bacillus licheniformis using microbially induced carbonate precipitation (MICP) technology, as well as the bactericidal properties of the biomineralized product vaterite. The changes in carbonic anhydrase activity, pH, carbonate and bicarbonate concentrations in different biomineralization systems were negatively correlated with variations in metal ion concentrations, while the changes in polysaccharides and protein contents in bacterial extracellular polymers were positively correlated with variations in barium concentrations. In the mixed calcium and barium systems, the harvested minerals were vaterite containing barium. The increasing concentrations of calcium promoted the incorporation and adsorption of barium onto vaterite. The presence of barium significantly increased the contents of O-CO, N-CO, and Ba-O in vaterite. Calcium promoted barium precipitation, but barium inhibited calcium precipitation. After being treated by immobilized bacteria, the concentrations of calcium and barium ions decreased from 400 and 274 to 1.72 and 0 mg/L (GB/T15454-2009 and GB8978-1996). Intracellular minerals were also vaterite containing barium. Extracellular vaterite exhibited bactericidal properties. This research presents a promising technique for simultaneously removing and recycling hazardous heavy metals and calcium in hypersaline wastewater.

The latitudinal gradient in rock-inhabiting bacterial community compositions in Victoria Land, Antarctica.

The harsh conditions in Victoria Land, Antarctica have formed a simple ecosystem dominated by microbes that use rocks as shelters to avoid environmental stressors. The area is composed of basement rocks that illustrate the history of complex deformation, thus it is highly valuable not only in perspectives of geology but also in biological aspects. Because this region is inhospitable to higher-level organisms and receives least external influences, it can be an ideal environment to investigate the relationship between rock-inhabiting bacterial communities and environmental factors. In such conditions, inorganics dissolved from minerals can be considered as key factors influencing rock-inhabiting bacterial communities. Thus, the present study attempted to explore rock-inhabiting bacterial communities throughout Victoria Land, to identify environmental parameters that are more influential on bacterial community compositions, and to investigate latitudinal gradients in environmental parameters and rock-inhabiting bacterial communities. The results suggested that (i) rock-inhabiting bacterial communities in Victoria Land predominately consisted of either Actinobacteria or Proteobacteria; (ii) latitudinal gradients in rock-inhabiting bacterial community compositions and some environmental parameters were observed; (iii) latitude, pH, nitrate, and sulfate significantly correlated with the dominant phyla; and (iv) the Classification and Regression Tree (CART) analysis demonstrated that latitude, pH, and sulfate concentrations could explain the dominant phylum with 89% accuracy. These findings can provide important insight into the link between environmental factors and rock-inhabiting bacterial community compositions in conditions with extremely cold temperatures and high levels of radiation, which could also be of interest in astrobiology.

Comparing rock-inhabiting microbial communities in different rock types from a high arctic polar desert.

Although rocks are habitable places for microbes in extreme environments, microbial diversity in these lithic environments is still poorly understood. The diversity and abundance of rock-inhabiting microbial communities in different types of rock in Svalbard, Norwegian High Arctic were examined using NGS sequencing of bacterial 16S rRNA genes and fungal 28S rRNA genes. Compositions of both bacterial and fungal communities varied across different rock types: sandstone, limestone, basalt, granite and travertine. Bacterial communities were dominated by Actinobacteria, Proteobacteria, Chloroflexi, Bacteroidetes and Acidobacteria. Fungal communities consisted of Eurotiomycetes, Lecanoromycetes, Dothideomycetes and Leotiomycetes. Both bacterial and fungal community compositions were significantly correlated with the geochemical characteristics of rocks. Bacterial communities were considerably correlated with the rock elements such as Mg and Ca. Fungal communities were considerably correlated with Fe. Interestingly, many dominant bacterial and fungal operational taxonomic units in the investigated rocks from the study area were closely affiliated to those found in other cold regions such as Alpine area, Arctic and Antarctica, suggesting that environmental constraints such as cold temperature may lead to convergence in microbial community composition. These results confirm that rocks in cold environments act as reservoirs of diverse bacteria and fungi, which may improve our understanding of lithic microbial ecology in the cold desert.

Brain and eyes of Kerygmachela reveal protocerebral ancestry of the panarthropod head.

Recent discoveries of fossil nervous tissue in Cambrian fossils have allowed researchers to trace the origin and evolution of the complex arthropod head and brain based on stem groups close to the origin of the clade, rather than on extant, highly derived members. Here we show that Kerygmachela from Sirius Passet, North Greenland, a primitive stem-group euarthropod, exhibits a diminutive (protocerebral) brain that innervates both the eyes and frontal appendages. It has been surmised, based on developmental evidence, that the ancestor of vertebrates and arthropods had a tripartite brain, which is refuted by the fossil evidence presented here. Furthermore, based on the discovery of eyes in Kerygmachela, we suggest that the complex compound eyes in arthropods evolved from simple ocelli, present in onychophorans and tardigrades, rather than through the incorporation of a set of modified limbs.

Complete Genome Sequence of Psychrobacter alimentarius PAMC 27889, a Psychrophile Isolated from an Antarctic Rock Sample.

Psychrobacter alimentarius PAMC 27889, a Gram-negative, psychrophilic bacterium, was isolated from an Antarctic rock sample. Here, we report the complete genome of P. alimentarius PAMC 27889, which has the nonmevalonate methylerythritol phosphate pathway of terpenoid biosynthesis and a complete gene cluster for benzoate degradation.

Complete Genome Sequence of Cryobacterium arcticum Strain PAMC 27867, Isolated from a Sedimentary Rock Sample in Northern Victoria Land, Antarctica.

Cryobacterium arcticum PAMC 27867, a psychrotolerant, Gram-positive bacterium, was isolated from a sedimentary rock sample collected at Eureka Spurs in northern Victoria Land, Antarctica. Here, we report the genome sequence of C. arcticum PAMC 27867.

A stem-group cnidarian described from the mid-Cambrian of China and its significance for cnidarian evolution.

Palaeontological data of extinct groups often sheds light on the evolutionary sequences leading to extant groups, but has failed to resolve the basal metazoan phylogeny including the origin of the Cnidaria. Here we report the occurrence of a stem-group cnidarian, Cambroctoconus orientalis gen. et sp. nov., from the mid-Cambrian of China, which is a colonial organism with calcareous octagonal conical cup-shaped skeletons. It bears cnidarian features including longitudinal septa arranged in octoradial symmetry and colonial occurrence, but lacks a jelly-like mesenchyme. Such morphological characteristics suggest that the colonial occurrence with polyps of octoradial symmetry is the plesiomorphic condition of the Cnidaria and appeared earlier than the jelly-like mesenchyme during the course of evolution.