ArfGAP1 inhibits mTORC1 lysosomal localization and activation.

The mammalian target of rapamycin complex 1 (mTORC1) integrates nutrients, growth factors, stress, and energy status to regulate cell growth and metabolism. Amino acids promote mTORC1 lysosomal localization and subsequent activation. However, the subcellular location or interacting proteins of mTORC1 under amino acid-deficient conditions is not completely understood. Here, we identify ADP-ribosylation factor GTPase-activating protein 1 (ArfGAP1) as a crucial regulator of mTORC1. ArfGAP1 interacts with mTORC1 in the absence of amino acids and inhibits mTORC1 lysosomal localization and activation. Mechanistically, the membrane curvature-sensing amphipathic lipid packing sensor (ALPS) motifs that bind to vesicle membranes are crucial for ArfGAP1 to interact with and regulate mTORC1 activity. Importantly, ArfGAP1 represses cell growth through mTORC1 and is an independent prognostic factor for the overall survival of pancreatic cancer patients. Our study identifies ArfGAP1 as a critical regulator of mTORC1 that functions by preventing the lysosomal transport and activation of mTORC1, with potential for cancer therapeutics.

SNAT7 regulates mTORC1 via macropinocytosis.

Mammalian target of rapamycin complex 1 (mTORC1) senses amino acids to control cell growth, metabolism, and autophagy. Some amino acids signal to mTORC1 through the Rag GTPase, whereas glutamine and asparagine activate mTORC1 through a Rag GTPase-independent pathway. Here, we show that the lysosomal glutamine and asparagine transporter SNAT7 activates mTORC1 after extracellular protein, such as albumin, is macropinocytosed. The N terminus of SNAT7 forms nutrient-sensitive interaction with mTORC1 and regulates mTORC1 activation independently of the Rag GTPases. Depletion of SNAT7 inhibits albumin-induced mTORC1 lysosomal localization and subsequent activation. Moreover, SNAT7 is essential to sustain KRAS-driven pancreatic cancer cell growth through mTORC1. Thus, SNAT7 links glutamine and asparagine signaling from extracellular protein to mTORC1 independently of the Rag GTPases and is required for macropinocytosis-mediated mTORC1 activation and pancreatic cancer cell growth.

AKAP13 couples GPCR signaling to mTORC1 inhibition.

The mammalian target of rapamycin complex 1 (mTORC1) senses multiple stimuli to regulate anabolic and catabolic processes. mTORC1 is typically hyperactivated in multiple human diseases such as cancer and type 2 diabetes. Extensive research has focused on signaling pathways that can activate mTORC1 such as growth factors and amino acids. However, less is known about signaling cues that can directly inhibit mTORC1 activity. Here, we identify A-kinase anchoring protein 13 (AKAP13) as an mTORC1 binding protein, and a crucial regulator of mTORC1 inhibition by G-protein coupled receptor (GPCR) signaling. GPCRs paired to Gαs proteins increase cyclic adenosine 3'5' monophosphate (cAMP) to activate protein kinase A (PKA). Mechanistically, AKAP13 acts as a scaffold for PKA and mTORC1, where PKA inhibits mTORC1 through the phosphorylation of Raptor on Ser 791. Importantly, AKAP13 mediates mTORC1-induced cell proliferation, cell size, and colony formation. AKAP13 expression correlates with mTORC1 activation and overall lung adenocarcinoma patient survival, as well as lung cancer tumor growth in vivo. Our study identifies AKAP13 as an important player in mTORC1 inhibition by GPCRs, and targeting this pathway may be beneficial for human diseases with hyperactivated mTORC1.

Viruses Regulate Microbial Community Assembly Together with Environmental Factors in Acid Mine Drainage.

Viruses are widespread in various ecosystems, and they play important roles in regulating the microbial community via host-virus interactions. Recently, metagenomic studies showed that there are extremely diverse viruses in different environments from the ocean to the human gut, but the influences of viral communities on microbial communities are poorly understood, especially in extreme environments. Here, we used metagenomics to characterize microbial communities and viral communities in acid mine drainage (AMD) and evaluated how viruses shape microbial community constrained by the harsh environments. Our results showed that AMD viral communities are significantly associated with the microbial communities, and viral diversity has positive correlations with microbial diversity. Viral community explained more variations of microbial community composition than environmental factors in AMD of a polymetallic mine. Moreover, we found that viruses harboring adaptive genes regulate a relative abundance of hosts under the modulation of environmental factors, such as pH. We also observed that viral diversity has significant correlations with the global properties of microbial cooccurrence networks, such as modularity. In addition, the results of null modeling analyses revealed that viruses significantly affect microbial community phylogeny and play important roles in regulating ecological processes of community assembly, such as dispersal limitation and homogenous dispersal. Together, these results revealed that AMD viruses are critical forces driving microbial network and community assembly via host-virus interactions. IMPORTANCE Viruses as mobile genetic elements play critical roles in the adaptive evolution of their hosts in extreme environments. However, how viruses further influence microbial community structure and assembly is still unclear. A recent metagenomic study observed diverse viruses unexplored in acid mine drainage, revealing the associations between the viral community and environmental factors. Here, we showed that viruses together with environmental factors can constrain the relative abundance of host and microbial community assembly in AMD of copper mines and polymetallic mines. Our results highlight the importance of viruses in shaping the microbial community from the individual host level to the community level.

The lncRNA NEAT1 Mediates Neuronal Cell Autophagy and Related Protein Expression After Cerebral Ischemia‒Reperfusion Injury.

The present study focuses on the role of the long noncoding RNA (lncRNA) NEAT1 in regulating autophagy during the ischemia‒reperfusion (I/R) injury process and its possible regulatory mechanism based on the results of laboratory experiments. Neuro-2a (N2a) cells and BV-2 microglial cells were cultured separately, and oxygen-glucose deprivation/reoxygenation (OGD/R) was induced in vitro to mimic cerebral I/R injury. The expression of lncRNA NEAT1 was measured after reoxygenation for different durations, and the results showed that NEAT1 expression was significantly different after OGD/R for 12 h; thus, cell models of NEAT1 overexpression and knockdown were constructed. Knockdown of NEAT1 effectively relieved reperfusion injury. In an N2a and BV-2 cell coculture system, knockdown of NEAT1 reduced autophagic flow in neuronal cells after reperfusion. To clarify the mechanism of NEAT1 after neuronal I/R injury, label-free quantitative proteomics (LFQ) was used to identify the differentially expressed proteins (DEPs) in NEAT1 knockdown neurons after OGD/R for 12 h. Additionally, Gene Ontology (GO) enrichment, protein‒protein interaction (PPI) network and parallel-reaction monitoring (PRM) quantitative analyses were carried out; the results showed that the expression levels of the autophagy-related proteins Gaa, Glb1, Prkaa1, Kif23, Sec24a and Vps25 were significantly reduced and that these proteins interact. In summary, this study shows that NEAT1 can regulate the interactions between autophagy-related proteins after neuronal I/R injury, reducing the level of autophagy and relieving neuronal reperfusion injury.

Inoculation with thermophiles enhanced the food waste bio-drying and complicated interdomain ecological networks between bacterial and fungal communities.

Bio-drying is a practical approach for treating food waste (FW). However, microbial ecological processes during treatment are essential for improving the dry efficiency, and have not been stressed enough. This study analyzed the microbial community succession and two critical periods of interdomain ecological networks (IDENs) during FW bio-drying inoculated with thermophiles (TB), to determine how TB affects FW bio-drying efficiency. The results showed that TB could rapidly colonize in the FW bio-drying, with the highest relative abundance of 5.13%. Inoculating TB increased the maximum temperature, temperature integrated index and moisture removal rate of FW bio-drying (55.7 °C, 219.5 °C, and 86.11% vs. 52.1 °C, 159.1 °C, and 56.02%), thereby accelerating the FW bio-drying efficiency by altering the succession of microbial communities. The structural equation model and IDEN analysis demonstrated that TB inoculation complicated the IDENs between bacterial and fungal communities by significantly and positively affecting bacterial communities (b = 0.39, p < 0.001) and fungal communities (b = 0.32, p < 0.01), thereby enhancing interdomain interactions between bacteria and fungi. Additionally, inoculation TB significantly increased the relative abundance of keystone taxa, including Clostridium sensu stricto, Ochrobactrum, Phenylobacterium, Microvirga and Candida. In conclusion, the inoculation of TB could effectively improve FW bio-drying, which is a promising technology for rapidly reducing FW with high moisture content and recovering resources from it.

Soil microbial community assembly model in response to heavy metal pollution.

Heavy metal pollution affected the stability and function of soil ecosystem. The impact of heavy metals on soil microbial community and the interaction of microbial community has been widely studied, but little was known about the response of community assembly to the heavy metal pollution. In this study, we collected 30 soil samples from non (CON), moderately (CL) and severely (CH) contaminated fields. The prokaryotic community was studied using high-throughput Illumina sequencing of 16s rRNA gene amplicons, and community assembly were quantified using phylogenetic-bin-based null approach (iCAMP). Results showed that diversity and composition of both bacterial and archaeal community changed significantly in response to heavy metal pollution. The microbial community assembly tended to be more deterministic with the increase of heavy metal concentration. Among the assembly processes, the relative importance of homogeneous selection (deterministic process) increased significantly (increased by 16.2%), and the relative importance of drift and dispersal limitation (stochastic process) decreased significantly (decreased by 11.4% and 5.4%, respectively). The determinacy of bacterial and archaeal community assembly also increased with heavy metal stress, but the assembly models were different. The deterministic proportion of microorganisms tolerant to heavy metals, such as Thiobacillus, Euryarchaeota and Crenarchaeota (clustered in bin 32, bin59 and bin60, respectively) increased, while the stochastic proportion of microorganisms sensitive to heavy metals, such as Koribacteraceae (clustered in bin23) increased. Therefore, the heavy metal stress made the prokaryotic community be deterministic, however, the effects on the assembly process of different microbial groups differed obviously.

Application of ultraviolet-visible spectroscopy coupled with support vector regression for the quantitative detection of thiamethoxam in tea.

A model combining UV-visible (UV-Vis) spectroscopy and support vector regression (SVR) for the quantitative detection of thiamethoxam in tea is proposed. First, each original UV-Vis spectrum in the sample set is decomposed into some intrinsic mode functions (IMFs) and a residual via ensemble empirical mode decomposition. Next, the decomposed IMFs are reconstructed into high-frequency and low-frequency matrices, and the residuals are combined into a trend matrix. Then, the SVR is used to build regression sub-models between each matrix and the content of thiamethoxam in tea. Finally, the combination model is established by a weighted average of the sub-models. The prediction results are compared with SVR and SVR coupled with several preprocessing methods, and the results demonstrate the superiority of the proposed approach in the quantitative detection of thiamethoxam in tea.

A-kinase anchoring protein 8L interacts with mTORC1 and promotes cell growth.

mTOR complex 1 (mTORC1) senses nutrients to mediate anabolic processes within the cell. Exactly how mTORC1 promotes cell growth remains unclear. Here, we identified a novel mTORC1-interacting protein called protein kinase A anchoring protein 8L (AKAP8L). Using biochemical assays, we found that the N-terminal region of AKAP8L binds to mTORC1 in the cytoplasm. Importantly, loss of AKAP8L decreased mTORC1-mediated processes such as translation, cell growth, and cell proliferation. AKAPs anchor protein kinase A (PKA) through PKA regulatory subunits, and we show that AKAP8L can anchor PKA through regulatory subunit Iα. Reintroducing full-length AKAP8L into cells restored mTORC1-regulated processes, whereas reintroduction of AKAP8L missing the N-terminal region that confers the interaction with mTORC1 did not. Our results suggest a multifaceted role for AKAPs in the cell. We conclude that mTORC1 appears to regulate cell growth, perhaps in part through AKAP8L.

Glutamine and asparagine activate mTORC1 independently of Rag GTPases.

Nutrient sensing by cells is crucial, and when this sensing mechanism is disturbed, human disease can occur. mTOR complex 1 (mTORC1) senses amino acids to control cell growth, metabolism, and autophagy. Leucine, arginine, and methionine signal to mTORC1 through the well-characterized Rag GTPase signaling pathway. In contrast, glutamine activates mTORC1 through a Rag GTPase-independent mechanism that requires ADP-ribosylation factor 1 (Arf1). Here, using several biochemical and genetic approaches, we show that eight amino acids filter through the Rag GTPase pathway. Like glutamine, asparagine signals to mTORC1 through Arf1 in the absence of the Rag GTPases. Both the Rag-dependent and Rag-independent pathways required the lysosome and lysosomal function for mTORC1 activation. Our results show that mTORC1 is differentially regulated by amino acids through two distinct pathways.

Mobile genetic elements mediate the mixotrophic evolution of novel Alicyclobacillus species for acid mine drainage adaptation.

Alicyclobacillus species inhabit diverse environments and have adapted to broad ranges of pH and temperature. However, their adaptive evolutions remain elusive, especially regarding the role of mobile genetic elements (MGEs). Here, we characterized the distributions and functions of MGEs in Alicyclobacillus species across five environments, including acid mine drainage (AMD), beverages, hot springs, sediments, and soils. Nine Alicyclobacillus strains were isolated from AMD and possessed larger genome sizes and more genes than those from other environments. Four AMD strains evolved to be mixotrophic and fell into distinctive clusters in phylogenetic tree. Four types of MGEs including genomic island (GI), insertion sequence (IS), prophage, and integrative and conjugative element (ICE) were widely distributed in Alicyclobacillus species. Further, AMD strains did not possess CRISPR-Cas systems, but had more GI, IS, and ICE, as well as more MGE-associated genes involved in the oxidation of iron and sulfide and the resistance of heavy metal and low temperature. These findings highlight the differences in phenotypes and genotypes between strains isolated from AMD and other environments and the important role of MGEs in rapid environment niche expansions.

mTOR signaling in stem and progenitor cells.

The mammalian target of rapamycin (mTOR) senses nutrients and growth factors to coordinate cell growth, metabolism and autophagy. Extensive research has mapped the signaling pathways regulated by mTOR that are involved in human diseases, such as cancer, and in diabetes and ageing. Recently, however, new studies have demonstrated important roles for mTOR in promoting the differentiation of adult stem cells, driving the growth and proliferation of stem and progenitor cells, and dictating the differentiation program of multipotent stem cell populations. Here, we review these advances, providing an overview of mTOR signaling and its role in murine and human stem and progenitor cells.

Expression and functional characterization of INPP4B in gallbladder cancer patients and gallbladder cancer cells.

BACKGROUND: Inositol polyphosphate 4-phosphatase type II (INPP4B) is a negative regulator of the PI3K-Akt signalling pathway and plays a contradictory role in different types of cancers. However, the its biological role played by INPP4B in human gallbladder cancer (GBC) has not been elucidated. In this study, we investigated the expression, clinical significance and biological function of INPP4B in GBC patients and cell lines. METHODS: The INPP4B protein expression levels in gallbladder cancer tissues and normal gallbladder tissues were detected by immunohistochemistry, and the clinical significance of INPP4B was analysed. Knockdown and overexpression of INPP4B in GBC-SD and SGC-996 cells followed by cell proliferation, clonogenic, apoptosis detection, scratch wound-healing and transwell assays were used to identify INPP4B function in vitro. RESULTS: INPP4B was up-regulated in human GBC tissues compared with normal gallbladder tissues and was related to histopathological differentiation (p = 0.026). Here, we observed that INPP4B was highly expressed in high-moderately differentiated tumours compared with low-undifferentiated tumours (p = 0.022). Additionally, we found that INPP4B expression was not associated with overall survival of GBC patients (p = 0.071) and was not an independent prognostic factor. Furthermore, when we stratified the relationship between INPP4B expression and the prognosis of GBC based on histopathological differentiation, we found that INPP4B played a contradictory role in GBC progression depending on the degree of differentiation. In addition, INPP4B knockdown inhibited the proliferation, colony formation, migration and invasion in GBC cells, while INPP4B overexpression had the opposite effects in vitro, which indicates its role as an oncoprotein. CONCLUSIONS: These findings suggested that INPP4B may play a dual role in the prognosis of GBC depending on the degree of differentiation and that INPP4B might act as an oncogene in gallbladder cancer cells.

Soil potentials to resist continuous cropping obstacle: Three field cases.

Continuous cropping has become the most common system in intensive, modern agricultural production; however, obstacles often appear in continuous cropping patterns after a few years of use. There have been several studies about the impacts of continuous cropping on soil microbial, but few about differences between soil experiencing continuous cropping obstacles and those where such obstacles had been resisted. Here, after ten or twenty years of continuous tobacco cropping, we collected soil samples investigating discrepancies in soil property and bacterial community between soils experiencing continuous cropping obstacles and soils where the obstacles were resisted providing insight into preventing and controlling continuous cropping obstacles. Results showed that soil organic matter (SOM), available phosphorus (AP), total nitrogen (TN), nitrate-N (NO3--N), and bacterial diversity of samples where continuous cropping obstacles had been resisted were significantly higher than those where continuous cropping obstacles were present. Besides, SOM, AP, TN, and Ammonium-N (NH4+-N) considerably affected the bacterial community. Among all variables, NH4+-N explained the largest proportion of bacterial community variation. Molecular ecological networks were used to putatively identify keystone taxa, including Acidobacteria Gp1, Acidobacteria Gp2, Acidobacteria Gp16, and WPS-1_genera_incertae_sedis. Their relative abundance significantly changed between the two conditions. Overall, our results indicate that decreases in soil nutrient content and bacterial diversity, and significant changes in some keystone taxa abundances may be important factors leading to increased soil-borne diseases and reduced tobacco production potential or quality. Thus, during agricultural production, we could regulate the stability of the soil-crop-microbial ecological system via crop rotation, intercropping, or the use of specialized bio-fertilizers and soil conditioners to mitigate continuous cropping obstacles.

Bacterial adaptive strategies to cope with metal toxicity in the contaminated environment - A review.

Heavy metal contamination poses a serious environmental hazard, globally necessitating intricate attention. Heavy metals can cause deleterious health hazards to humans and other living organisms even at low concentrations. Environmental biotechnologists and eco-toxicologists have rigorously assessed a plethora of bioremediation mechanisms that can hamper the toxic outcomes and the molecular basis for rejuvenating the hazardous impacts, optimistically. Environmental impact assessment and restoration of native and positive scenario has compelled biological management in ensuring safety replenishment in polluted realms often hindered by heavy metal toxicity. Copious treatment modalities have been corroborated to mitigate the detrimental effects to remove heavy metals from polluted sites. In particular, Biological-based treatment methods are of great attention in the metal removal sector due to their high efficiency at low metal concentrations, ecofriendly nature, and cost-effectiveness. Due to rapid multiplication and growth rates, bacteria having metal resistance are advocated for metal removal applications. Evolutionary implications of coping with heavy metals toxicity have redressed bacterial adaptive/resistance strategies related to physiological and cross-protective mechanisms. Ample reviews have been reported for the bacterial adaptive strategies to cope with heavy metal toxicity. Nevertheless, a holistic review summarizing the redox reactions that address the cross-reactivity mechanisms between metallothionein synthesis, extracellular polysaccharides production, siderophore production, and efflux systems of metal resistant bacteria are scarce. Molecular dissection of how bacteria adapt themselves to metal toxicity can augment novel and innovative technologies for efficient detoxification, removal, and combat the restorative difficulties for stress alleviations. The present comprehensive compilation addresses the identification of newer methodologies, summarizing the prevailing strategies of adaptive/resistance mechanisms in bacterial bioremediation. Further pitfalls and respective future directions are enumerated in invigorating effective bioremediation technologies including overexpression studies and delivery systems. The analysis will aid in abridging the gap for limitations in heavy metal removal strategies and necessary cross-talk in elucidating the complex cascade of events in better bioremediation protocols.

Development of the yeast and lactic acid bacteria co-culture agent for atmospheric ammonia removing: Genomic features and on-site applications.

Odorous gas (e.g. atmospheric ammonia) in low ventilation public places, such as public toilets and waste transfer stations, causes severe health problems. Many technologies are developed to purify the atmospheric ammonia, among which the microbial agents are supposed to be a green and economical approach. In this study, we developed a yeast, Pichia sp. J1, and a lactic acid bacterium (LAB), Lactobacillus paracasei B1, co-culture agent for atmospheric ammonia removing. The on-site application results indicated the yeast and LAB mixed fermented agent had a maximum ammonia removing efficiency of 98.78%, which is significantly higher than the pure cultures (78.93% for B1 and 75.00% for J1), indicating the co-culture agent is an excellent biological product for ammonia removal. The excellent performance of the agent is closely related to the synergy behaviors between the yeast and LAB. In the co-culture agents, some of the LAB cells adhered closely to the yeast, and the growth and lactic acid producing ability of LAB were significantly promoted by yeast. Genomic analysis indicated the complementary of nutrients, i.e. carbon and nitrogen resources, signal transduction, and adhesion proteins (regulates adhesion behavior) played roles in regulating the synergy effects. Our study offers a novel biological solution of odorous gas purification.

Vertical distribution of the toxic metal(loid)s chemical fraction and microbial community in waste heap at a nonferrous metal mining site.

Over the past few decades, nonferrous mining has produced numerous waste rock and part of the waste that has not been properly treated was generally dumped at roadsides and hill slopes. However, the vertical distributions of toxic metal(loid)s and composition of microbial communities in waste heap and the under-laid pristine soil are rarely studied. In this work, the fraction-related distributions of toxic metal(loid)s were investigated at a waste heap profile and the indigenous microbial assemblages were also analyzed by Illumina sequencing of 16 s rRNA genes. Results showed that compared to the under-laid pristine soil, content of toxic metal(loid)s, especially Cd, As and Pb, in waste rock layer were higher. Most of As in subsoil existed as non-specifically sorbed and specifically-sorbed fractions, which could be ascribed to the migration from the upper layer. The mobility was significantly correlated with Eh, EC, clay content, CEC and the total content of metal(loid)s. Phyla Proteobacteria, Acidobacteria and Firmicutes dominated the microbial communities. The microbial community compositions at the genus level were similar, but their relative abundances were mainly influenced by pH, CEC, Eh, SOM, and bioavailability content of toxic metal(loid)s. Besides, microbial functions of elements (S, Fe, Mn and As) oxidation/reduction and metabolites (siderophore, biosurfactant, organic acid, phosphatase and urease) potentially were used for pollutants bioremediation.

The utilization of biomineralization technique based on microbial induced phosphate precipitation in remediation of potentially toxic ions contaminated soil: A mini review.

In recent years, many studies have been devoted to investigate the application of microbial induced phosphate precipitation (MIPP) process for potentially toxic element polluted soil remediation. MIPP biomineralization technique exhibits a great potential to efficiently remediate polluted soil considering its low cost, green and ecofriendly process, and simple in operation. This paper represented a review on the state of the art of polluted soil remediation based on MIPP technique. Briefly, certain defined criteria on targeted microbe selection was discussed; an overall review on the utilization of MIPP process for toxic ions biomineralization in soil was provided; influencing factors reported in the literature, such as pH, temperature, humic substances, coexisting ions, effective microbial population, and enzyme activity, were then comprehensively reviewed; finally; a special emphasis was given to enhance MIPP remediation performance in soil in future research.

Comparative Genomic Analysis Reveals the Distribution, Organization, and Evolution of Metal Resistance Genes in the Genus Acidithiobacillus.

Members of the genus Acidithiobacillus, which can adapt to extremely high concentrations of heavy metals, are universally found at acid mine drainage (AMD) sites. Here, we performed a comparative genomic analysis of 37 strains within the genus Acidithiobacillus to answer the untouched questions as to the mechanisms and the evolutionary history of metal resistance genes in Acidithiobacillus spp. The results showed that the evolutionary history of metal resistance genes in Acidithiobacillus spp. involved a combination of gene gains and losses, horizontal gene transfer (HGT), and gene duplication. Phylogenetic analyses revealed that metal resistance genes in Acidithiobacillus spp. were acquired by early HGT events from species that shared habitats with Acidithiobacillus spp., such as Acidihalobacter, Thiobacillus, Acidiferrobacter, and Thiomonas species. Multicopper oxidase genes involved in copper detoxification were lost in iron-oxidizing Acidithiobacillus ferridurans, Acidithiobacillus ferrivorans, and Acidithiobacillus ferrooxidans and were replaced by rusticyanin genes during evolution. In addition, widespread purifying selection and the predicted high expression levels emphasized the indispensable roles of metal resistance genes in the ability of Acidithiobacillus spp. to adapt to harsh environments. Altogether, the results suggested that Acidithiobacillus spp. recruited and consolidated additional novel functionalities during the adaption to challenging environments via HGT, gene duplication, and purifying selection. This study sheds light on the distribution, organization, functionality, and complex evolutionary history of metal resistance genes in Acidithiobacillus spp.IMPORTANCE Horizontal gene transfer (HGT), natural selection, and gene duplication are three main engines that drive the adaptive evolution of microbial genomes. Previous studies indicated that HGT was a main adaptive mechanism in acidophiles to cope with heavy-metal-rich environments. However, evidences of HGT in Acidithiobacillus species in response to challenging metal-rich environments and the mechanisms addressing how metal resistance genes originated and evolved in Acidithiobacillus are still lacking. The findings of this study revealed a fascinating phenomenon of putative cross-phylum HGT, suggesting that Acidithiobacillus spp. recruited and consolidated additional novel functionalities during the adaption to challenging environments via HGT, gene duplication, and purifying selection. Altogether, the insights gained in this study have improved our understanding of the metal resistance strategies of Acidithiobacillus spp.

Effects of redox potential on soil cadmium solubility: Insight into microbial community.

Understanding the role of microbes in the solubility of cadmium (Cd) is of fundamental importance for remediation of Cd toxicity. The present study aimed to identify the microbes that involved in regulating Cd solubility and to reveal possible mechanisms. Therefore, microbial communities were investigated through high-throughput sequencing approach, the molecular ecological network was constructed and metagenomes were predicted. Our results indicated that redox conditions affected both the solubility of soil Cd and the microbial communities. Anaerobic microbes, such as Anaerolineaceae, did not only play important roles in shaping the microbial community in soils, but might also be involved in regulating the Cd solubility. Two possible mechanisms that how Anaerolineaceae involved in Cd solubility are (1) Anaerolineaceae are important organic matter degraders under anoxic conditions and (2) Anaerolineaceae can co-exist with methane metabolism microbes, while methane metabolism promotes the precipitation of soluble Cd. Thus, application of Anaerolineaceae in bioremediation of soil Cadmium contamination is a potential approach. The study provided a novel insight into the role of microbial community in the regulation of Cd solubility under different redox conditions, and suggested a potential approach for the remediation of soil Cd contamination.