Abstract:

Abstract:The total number of marine microorganisms is estimated to be 10³⁰. They are the key components driving marine energy and material recycling and maintaining ecological balance. Research advances in marine microbial diversity contribute to our understanding of the operative mechanisms of marine ecosystems. These knowledges can guide our respondence to ecological crisis of global oceans and our exploration of marine microbial resources. As the number of culturable marine microorganisms is currently low, our knowledges to the abundance, physiological characteristics and ecological functions of marine microbial communities are greatly limited. Ribosomal RNA sequencing technologies can rapidly and accurately identify or classify microorganisms based on nucleic acid sequences at low-cost. These technologies have been used in studying community structure and evolutionary and ecological relationships between microorganisms. In recent years, with the benefit of rapid development in sequencing technologies, marine microbial studies based ribosomal RNA sequencing analyses have achieved remarkable progresses in discovering novel marine microbial lineages, revealing ecological mechanisms and evolutionary relationships between marine microorganisms, discovering novel metabolites and applying in marine bioremediation. In this review, we introduce the technical principles of ribosomal RNA sequencing, the application of three generations of sequencing technologies in studying marine microbial diversity, and variable combinations of library construction and sequencing technologies. Finally, we address prospectives in utilizing these sequencing strategies in studies with different purposes.

Abstract:Biological nitrogen fixation, a process through which nitrogen-fixing microorganisms reduce atmospheric nitrogen to bioavailable ammonia, is the main source of “new” nitrogen in the environment, regulates primary productivity and thus affects the balance of nitrogen storage. Because most of nitrogen-fixing microorganisms in the environments are yet uncultured, culture-independent single-cell techniques with a high-level spatial resolution have become a powerful tool for studying nitrogen-fixing microorganisms. In addition, ¹⁵N₂-stable isotope probing (SIP) provides a very direct means to characterize nitrogen fixation activity based on the amount or rate of ¹⁵N assimilated by microorganisms. This article reviews the latest progresses in applying two single-cell techniques of nanosecondary ion mass spectroscopy (NanoSIMS) and Raman spectroscopy integrated with ¹⁵N₂-SIP for studies of nitrogen-fixing microorganisms, including the discovery of novel active nitrogen-fixing species and their spatial distribution in the environment, symbiotic relationship with other organisms, cellular physiological states, etc. Perspective on future study of nitrogen-fixing microorganisms by single-cell Raman spectroscopy is provided.

Abstract:Microbial traits are core attributes closely related to microbial survival, growth and reproduction. These attributes could reflect the microbial responses to environmental changes, and then affect species distributions, community assembly processes, and relevant ecosystem functions. There is a growing recognition that, compared to microbial taxonomic information, microbial traits could expand our understanding of microbial ecological processes and provide mechanistic explanations of ecological patterns at the scales of population, community and ecosystem. Here, we address important ecological themes based on microbial traits in recent years, including the classification and determination of microbial traits, functional diversity and applications, the relationship between microbial traits and species distribution and community assembly, the effects of microbial traits on biodiversity and ecosystem functions and the response of microbial traits to global change. Although previous studies on microbial traits have been extended to all aspects of ecology and promoted the research and development of various frontier scientific problems, there are still many opportunities and challenges. Thus, we also provide perspectives such as research methods and directions based on microbial traits.

Abstract:Phylum Chloroflexi is a deep branching lineage of the domain Bacteria. Members of the phylum are widely distributed in different habitats of the biosphere. The validly published microbes in the phylum include 9 classes of only 56 species. The results based on molecular ecology imply the majority members of this phylum are still uncultured. Chloroflexi microbes are diverse in morphology, nutrition, metabolic pathways, and play important roles in biogeochemical cycles of multiple elements including carbon, nitrogen and sulfur. Study on Chloroflexi may contribute to understanding microbial diversity, metabolic characteristics and ecological processes in the environment, it is important in clarifying the adaptation of microorganisms to the environment and their evolution. In this paper, the discovery history, nutrition, metabolism and the role in the elemental cycling of Chloroflexi are summarized. Isolation methods and potential application values are also reviewed. Expectations for Chloroflexi cultivation, evolution and geochemical cycling are also indicated.

Abstract:Climate warming caused by the increase in atmospheric greenhouse gas concentration has brought serious impact on the sustainable development of human society. The hydrospheric ecosystem is not only one of the world's most important carbon sinks, but also the world's most important natural sources of methane emissions. Therefore, understanding of hydrospheric methane emission and related microbial mechanisms under climate warming is important to reveal the future trend of the earth's climate system and predict potential scenarios of future global change. Additionally, it will provide basic theoretical support for how to effectively utilize the potential of the carbon sink in the hydrosphere, in order to better respond to global climate change issues. In this paper, we review the status and trend of microbial-mediated methane emissions of the main hydrospheric ecosystems under climate warming, and introduce the complex regulatory effects of climate warming on microbial communities and functions related to methane metabolisms. In view of the current research status, it is urgent to carry out related researches based on the complexity of ecosystems and the long-term nature of climate warming through a combination of micro-mechanisms and macro-processes. Meanwhile, it is suggested to strengthen the researches in relatively weak areas such as the ocean.

Abstract:Marine Group II (MGII) is the most abundant archaeal group in surface ocean waters. At present, no pure culture of the group has been isolated successfully since they were discovered in 1992. Analysis of the 16S rRNA genes has revealed that MGII mainly consist of two groups, MGIIa and MGIIb, which perform photoheterotrophy and potentially play an important role in marine carbon cycle. Phylogenetic classification based on the 16S rRNA gene assigned MGIIa and MGIIb as two families within an order-level lineage under Thermoplasmata. The phylogenetic position of a third group, MGIIc, is ambiguous due to the lack of their 16S rRNA gene sequences and absence in the metagenome data. This mini-review aims to provide the latest information on the distribution, abundance and diversity, metabolic capabilities and potential ecological functions, as well as efforts being made in enrichment and isotope labeling studies of MGII. Insights on future research directions are also provided.

Abstract:Nitrous oxide (N₂O) is a powerful greenhouse gas, and also the main compound causing stratospheric ozone depletion. The ocean is an important source of N₂O emission to the atmosphere, and N₂O in the ocean is mainly produced by the microbial-mediated nitrogen biogeochemical cycle. This paper firstly reviews the marine N₂O emission flux, the distribution characteristics of seawater N₂O and environmental impact factors. Then, the microbial processes regulating the N₂O production and emission are discussed. At last, we address the N₂O biogeochemical process based on the relationship between low oxygen and N₂O production in the estuarine and coastal ecosystems.

Abstract:[Objective] Dimethylsulfoniopropionate (DMSP) and its cleavage product dimethyl sulfide (DMS) play important roles in sulfur cycle of the marine environment. At present, some studies focus on the distribution of DMSP catabolizing bacteria, while studies on DMSP producing bacteria are just beginning. The objective of this study was to analyze the horizontal and vertical (1000 m depth) distribution of DMSP producing and catabolizing bacteria as well as genes in the East China Sea, and to study their responses to environmental parameters. [Methods] We quantified the abundance of microplankton by using flow cytometry. We measured the abundance of DMSP producing (dsyB and mmtN) and catabolising (dddP and dmdA including C/2 and D/1 subclade) genes and organisms by qPCR and high-throughput amplicon sequencing. [Results] The abundances of Synechococcus, Prochlorococcus, picoeukaryotes and heterotrophic bacteria increased and then decreased in the vertical profile with maximum located at 30-50 m depth. Surface water samples (~4 m) possessed the highest abundance of DMSP producing and catabolizing genes as well as the abundance of DMSP producers (Alteromonas, Phaeobacter and Pelagibaca). With increasing water depth, the abundances of DMSP producing and catabolizing genes and organisms increased and then decreased with peak values at the 100-150 m depth. The abundance of DMSP catabolizing genes decreased rapidly in the water below 100 m depth. However, the abundance of DMSP producing genes decreased slowly in the water below 100 m depth and even increased in the waters from 500 m to 1022 m depth. In contrast, the abundances of DMSP producing and catabolizing genes and organisms did not show apparent horizontal distribution patterns. The bacterial community composition showed significant difference between shallow water (≤100 m) and deep water (>100 m), and the relative abundance of the Flavobacteriia, Actinobacteria and Cyanobacteria in the shallow water were higher than that in the deep water, in contrast with an opposite trend for the Alphaproteobacteria in the deep water. [Conclusion] Bacterial communities differed significantly between waters below and above the 100 m depth. The surface water possessed the highest abundance of DMSP producing and catabolizing bacteria, followed by the 100-150 m water, with DMSP producing and catabolizing bacteria showing significantly different variation trends in the waters of 100-1022 m depth.

Abstract:[Objective] To understand the growth characteristics of deep subseafloor fungi adapted to the in-situ environment. [Methods] The growth rates of four strains of Schizophyllum commune isolated from coal-bearing sediments about 2 km below the seafloor and two strains isolated from marine and terrestrial habitats were studied by comparative culture under different environmental factors, mimicking the in-situ conditions (except for pressure) such as temperature, pH, salinity, Fe²⁺, lignin, and NH₄⁺. [Results] All the strains of subseafloor fungus grew significantly better than terrestrial (CFCC7252) and marine (MCCC 3A00233) isolated strains under the given culture conditions, including temperature (20, 30, 40, 45 ℃), oxygen (aerobic and anaerobic), pH (6, 8, 10), salinity (freshwater, in-situ water, artificial seawater), Fe²⁺ (0.27, 8.93, 89.28 μmol/L), lignin (1, 5, 10 g/L), and NH₄⁺ (0.5, 1.0, 5.0 g/L). However, there were also differences among different strains in the sedimentary environment below seafloor. The growth rate of strains 6R-2-F01 and 24R-3-F01 under anaerobic conditions was significantly higher than that of aerobic conditions. [Conclusion] Fungi from the subseafloor, such as S. commune, may have distinct biological traits that help them adapt to the extreme marine subsurface environments.

Abstract:After the Deepwater Horizon accident in 2010, a large number of “marine oil snow” (MOS) were observed in the oil-polluted area of the Gulf of Mexico. MOS is a kind of agglomerate composed of oil, phytoplankton and bacterial slime, which can sink oil from the sea surface to the seafloor and has great influence to the weathering process of oil. Therefore, investigating the formation mechanism and ecological effect of marine oil snow is of great significance for further understanding the role of marine oil snow in the oil-ocean system. In this paper, the formation mechanism of MOS is discussed from three aspects of physical agglomeration, microorganism and oil dispersant, and the influences of MOS on oil weathering, benthos toxicity and migration and transformation of other pollutants are analyzed. Finally, future research directions are proposed.

Abstract:Archaea are important components of marine microorganisms and widely distributed in various marine environments. They play vital roles in the biogeochemical cycles and the evolution of life on Earth. Up to now, archaea include 4 superphyla (Euryarchaeota, TACK, Asgard, and DPANN) and about 30 different phyla. To provide clues and ideas for further research on archaea from coastal or hadal sediments, this review summarizes the recent progresses on the distribution and metabolic features of four common archaeal groups, including Bathyarchaeota, Woesearchaeota, Asgard archaea, and Thermoprofundales (Marine Benthic Group D).

Abstract:In natural freshwater and low-salinity waters, bloom-forming cyanobacteria often live in the form of cyanobacterial aggregates. Many heterotrophic bacteria colonize in the cyanobacterial aggregates, subsequently they constitute the fundamental unit with unique ecological functions. Compared with single-celled cyanobacteria, cyanobacterial aggregates exhibit many unique characteristics, e.g., rich organic matter, steep redox gradient, and complex inter-specific interactions. These properties enable cyanobacterial aggregates to become the hotspot for elemental biogeochemical cycling in aquatic ecosystems. Meanwhile, the inter-specific interactions within cyanobacterial aggregates are far more intense compared to those between single-celled algae and free-living bacteria. This review introduces current research progress on these aspects, with a focus on the biological, physiological and chemical processes within cyanobacterial aggregates, and discusses the micro-mechanisms of the macro-phenomena. In the future, the omic research of cyanobacterial aggregates and the construction of multi-omic microecological databases may become the key for exploring life processes within cyanobacterial aggregates and for revealing the mechanisms of cyanobacterial bloom outbreak.

Abstract:[Objective] Dimethylsulfoniopropionate (DMSP) is one of the main organic sulfides in the ocean, and the main source of sulfur for marine bacteria. DMSP is catabolized by bacteria into dimethylsulfide (DMS), driving the sulfur cycle of the Earth. This study simulated the effect of seawater eutrophication on DMSP/DMS, DMSP producing genes (dsyB and mmtN), catabolising genes (dddP and dmdA) and corresponding functional bacteria through the mesocosm. [Methods] We used flow cytometry to quantify the abundance of microplankton of 92 water samples. We sequenced bacterial 16S rRNA gene of seawater samples by high-throughput sequencing. Then we quantified the abundance of 16S rRNA gene, DMSP producing and catabolising genes by quantitative PCR. [Results] Adding nitrate (6.00 μmol/L) and phosphate (0.375 μmol/L) simultaneously increased the concentration of chlorophyll a, DMSP and DMS. For DMSP producing genes, phosphate enriched the abundance of dsyB and some DMSP producing genera, such as Phaeobacter. Adding nitrate and phosphate could enrich dsyB simultaneously, inhibit the growth of Alteromonas and the enrichment of mmtN gene, but the effects of phosphate on dsyB enrichment was better than nitrate. In terms of DMSP catabolising genes, adding nitrate and phosphate simultaneously promoted the enrichment of dddP and the DMSP catabolising genera like Thalassococcus, Thalassobius, Loktanella and Shimia, but inhibited the enrichment of SAR11, Sulfitobacter and other species, resulting in the failure of enrichment of dmdA. Nitrogen restriction could better promote the abundance of DMSP producing gene, resulting in the increasing of bacterial DMSP production to cope with the insufficient nutritional conditions, and rising the proportion of DMSP demethylation to provide more energy for bacteria. However, in the case of nitrate and phosphate abundance, bacteria were apt to reduce the synthesis of DMSP and was more inclined to lyse DMSP to produce DMS in order to reduce the ratio of sulfur assimilation. [Conclusion] The results of this study emphasized the effect of seawater eutrophication on the bacterial DMSP production and catabolism.

Abstract:Microbial carbon sequestration in the ocean plays an important role in marine carbon storage to alleviate the global climate change. Lignin is the second most abundant carbon pool formed by photosynthesis on earth. The biogeochemical process in the ocean, which is mediated by heterotrophic microorganisms, is closely related to the marine carbon cycle. In recent years, the rapidly developing high-throughput sequencing technology, together with the traditional microbial technology, provides insights into the lignin-degrading microbial community, novel lignin-metabolizing microbial species, and functional genes in open environments. However, numerous studies focused on the terrestrial ecosystem, rather than marine ecosystem. The biogeochemical process of such terrestrial organic carbon in the ocean remains elusive. Therefore, analyzing the marine lignin transformation is essential in the study of marine carbon cycle. This article reviews not only the marine microbes involved in the lignin conversion, the mechanism of lignin metabolism and the links between microbial carbon metabolism and marine carbon sink, but also provides further ideas in the future.

Abstract:Nitrogen biogeochemical cycle is an important part of the global element cycle, and the key factor to affect the ecosystem productivity, safety of water resources, greenhouse gas emissions. Nitrogen cycle is a complex process mediated by microorganisms, and the transformation of different nitrogen forms is dominated by corresponding functional microorganisms. The recent findings of anaerobic ammonia oxidation (anammox) and complete ammonia oxidation (comammox) reshaped our understanding of nitrogen cycle. Here we summarize the occurrence, distribution and process mechanisms of anammox, comammox and dissimilatory nitrate reduction to ammonium (DNRA) processes in nature, especially in terrestrial and freshwater ecosystems, and review the interactions among the three newly developed cycles.

Abstract:[Objective] To investigate the adaptive mechanism of bioleaching microorganisms to extreme environment based on CRISPR system at the genomic level, bioinformatic analyses were performed on the structural characteristics and homology of CRISPR-Cas system in genomes of 100 species from genera (Acidithiobacillus, Desulfovibrio, Leptospirillum, Sulfobacillus, Acidiplasma and Ferroplasma) in acid mine environment. [Methods] We downloaded genome sequences from NCBI website and identified potential CRISPR arrays by using CRISPR Finder. The composition, structure and function of each CRISPR system were analyzed, where repeats were classified by Clustal Omega and spacers were aligned and annotated according to nr database, plasmid database and viral database, respectively. The CRISPR-Cas system of microorganisms in acid mine environment was classified based on the types and homology of Cas proteins. [Results] Among the genomes of 100 bioleaching microorganisms, we found 415 CRISPR arrays. There were 80 different repeats and 4147 spacers in 176 confirmed CRISPR arrays. All the 12 types of repeat sequences in each cluster could form typical RNA secondary structure and the sequence of cluster 10 was the most representative one among all the bioleaching microorganisms. The annotation results showed that these microorganisms have been attacked by bacterial plasmids and virus, and have resisted the invasion of foreign nucleic acid sequences through different defense mechanisms. Most of the CRISPR-Cas systems of bioleaching bacteria belong to I-C and I-E subtypes, while most of the CRISPR-Cas systems of archaea belong to I-D subtype. There are significant differences between them in the evolution process based on the CRISPR-Cas system. [Conclusion] The CRISPR structure of acid mine environment microorganisms may mediate the interaction between foreign nucleic acid sequence and Cas protein based on different immune mechanisms, which provides a foundation for further revealing the adaptive evolution mechanism of extreme environment microorganisms.

Abstract:[Objective] Haikou is rich in hot spring resources and the research on the microbial diversity of hot springs is conducive to the further development and utilization of the microbial resources in Hainan hot springs. [Methods] Microbial ITS sequences and V3-V4 region of 16S rRNA gene in three hot springs (Rongyu hot spring on haidian island, S1; Happy farm hot spring in the crater, S2; and west coast Haichangliu hot spring, S3) water samples were sequenced by Illumina HiSeq high-throughput sequencing technology and were analyzed by bioinformatics. [Results] Analysis of alpha diversity shows that in the fungal community, S3 > S1 > S2, and in the bacterial community, S2 > S1 > S3. Beta diversity analysis shows that the compositions of fungal and bacterial communities in the three hot springs were significantly different; Classification analysis shows that the dominant phyla of hot spring fungal community were Ascomycota and Basidiomycota and those of hot spring bacterial community were Proteobacteria, Bacteroidetes, Thermi, Nitrospirae, Chlorobi, Firmicutes, Chloroflexi, Actinobacteria; Canonical correspondence analysis shows that temperature was the main influencing factor on fungus community in the three hot springs, and total phosphorus on bacterial community. [Conclusion] Haikou hot springs have abundant microbial resources. The microbial community composition is mainly affected by temperature for fungi and total phosphorus for bacteria.

Abstract:Glaciers occupy roughly 11% of the Earth's land surface and possess about 10⁴ Pg organic carbon. As glaciers melt, organic carbon is released into downstream ecosystems, stimulating the primary productivity and affecting the ecosystem of oceans, lakes, and runoff. Microbial carbon-fixing processes determine organic carbon storage in glaciers and carbon output from glaciers to downstream ecosystems. Investigations on community composition and function of carbon-fixing microbes in glaciers can provide a data basis for estimating the carbon accumulation in glaciers and protecting their downstream ecosystems. This review summarized the carbon storage and release of glaciers, carbon fixing pathways, the community composition of carbon-fixing microorganisms in glacial ecosystems, carbon fixation rate, and influencing environmental factors, followed by prospects on future research directions of carbon-fixing microorganisms in glacial ecosystems.

Abstract:Under anoxic condition, a microorganism can transfer electrons directly to another microorganism (i.e., direct interspecies electron transfer or DIET) to couple the metabolic capability of the two microorganisms for their syntrophic growth. DIET between bacteria and archaea is the new way for energy exchange between bacteria and archaea as well as the new mechanisms for regulating their metabolisms. Furthermore, DIET between bacteria and archaea is directly involved in methane formation and the anoxic methane oxidation coupled to sulfate reduction. Thus, DIET between bacteria and archaea plays a crucial role in global biogeochemical transformation and cycling of carbon and sulfur. Finally, all currently available data suggest that multi-heme c-type cytochromes may form continuously extracellular electron transfer pathways to mediate electron transfer between the cytoplasmic membranes of bacteria and archaea via the multi-step hopping mechanism.

Abstract:The extracellular respiration of microbes is the key energy metabolism in the anaerobic environment, driving the global biogeochemical cycle of some key elements, like C, N, S and Fe. The discovery of microbial nanowire is a milestone in the study of extracellular respiration, which promoted the study of electromicrobiology. Microbial nanowires are conductive filaments growing on the surface of bacteria. They transfer intracellular metabolic electrons outward for the reduction of extracellular electron acceptors promoting extracellular respiration or they transfer electrons to other microbes forming syntrophic cocultures. This process broadens the knowledge on electron transfer in organism and expands the interactions between microorganism and the natural environment. Owing to the excellent conductivity, microbial nanowires have the prospect of a broad application. Studies on the conductivity, ecological functions and the applications in biomaterials, bioenergy, bioremediation and human health of microbial nanowires have been regarded as a pioneering field and the focus of research in electromicrobiology. However, the biological and ecological functions of microbial nanowires are unknown and the mechanism of electron transfer along nanowire is ambiguous. Here, we will begin by summarizing all published microbial nanowires and their reported characteristics and functions. Two representatives of Geobacter sulfurreducnes and Shewanella oneidensis are included to introduce the composition and structure of their microbial nanowires. Furthermore, after presenting the methods and technologies used for conductivity measurement, the conductivity models of microbial nanowires (metabolic-like conductivity and electron hopping) are discussed and compared. We also suggest future studies and applications of microbial nanowires. The problems, challenges and opportunities analyses of microbial nanowire study are also provided.

Abstract:[Objective] To analyze the physiological and electrochemical characteristics of a methanotrophs-associated bacteria isolated from the methanotrophic enrichments in the Yellow River Delta wetland soil, and to explore their effect on the methane oxidation process. [Methods] High-throughput sequencing was used to analyze microbial community of methanotrophic enrichments. The methanotrophs-associated strain was isolated using plate smearing and scribing method and initially identified by 16S rRNA gene sequencing. The morphology of the isolate was depicted by scanning electron microscopy. Gas chromatography was used to analyze the methane concentration, which showed the ability of utilizing methane and influence of improving methane oxidation by methanotroph. Two-chamber microbial fuel cells and Differential Pulse Voltammetry were used to test the electrochemical activity. [Results] The microbial community of methanotrophic enrichments from incubation of Yellow River Delta wetland soil included methanotrophs Methylobacter and other accompanying genera. We isolated a methanol-metabolizing bacterium, Pseudomonas putida P7 (with the similarity of 99.79%) which was a rod bacterium with the length between 1.5 μm and 2.5 μm and width about 0.5 μm. The GC analysis showed that this strain could not use methane but improved methane oxidation (P<0.05). The maximum current density was 28 mA/m², and the results of DPV revealed that the oxidation peak and reduction peak occurred at -0.17 V and -0.25 V, respectively. [Conclusion] We successfully isolated an electrochemical activity microbe, Pseudomonas putida P7, with ability of improving methane oxidation. This study deepened the understanding of the physiological characteristics and functions of the methanotroph-associated bacteria in the process of methane oxidation.

Abstract:Microbial electron transfer processes play a key role in both life evolution and biogeochemical cycles of various elements. In recent years, toward a deeper understanding of the microbial electron transfer, many novel microbial extracellular electron transfer strategies have been discovered, such as microbial nanowires, electrically conductive biofilms, interspecies electron transfer. Meanwhile, the electron transport distance increases from nanometer scale to centimeter scale. Generally, these long-distance microbial electron transport processes interacted and connected to each other, and form microbial electron transfer networks which play key roles in substance and energy transformations. The mechanisms and functions of microbial long-distance electron transport have been paid increasing attentions from different disciplines. Along the scale of electron transfer distance, this review introduces recent progresses in microbial long distance electron transport pathways and networks, including nanometer electron transport networks (cell periplasm space and outer surface), micro-to-millimeter electron transport networks (nanowire, inter-cellular electron transfer and conductive biofilms), and centimeter electron transport networks (cable bacteria). The challenges, problems and future research directions in this field are also discussed for providing more information to the researchers related.

Abstract:Minerals are an important carrier for absorption and conversion of energy in the inorganic nature. The extracellular electron transfer between microorganisms and minerals reflects the influence of mineral electronic energy on microbial growth and energy acquisition. According to the source and generation of electrons, previous studies have shown that the outermost or sub-outer valence electrons of the variable elements in minerals and the photoelectrons on the conduction band of semiconductor minerals are two different forms of extracellular electron energy, which generation and transfer methods are closely related to the electron carrier of the microbe-mineral interaction interface and energy conversion mechanism. In the process of extracellular electron transfer between minerals and microorganisms, different forms of mineral electronic energy have both similarities and differences. In addition, microbial intracellular-extracellular electron transfer pathways also affect the absorption and acquisition of mineral electronic energy, which affects microbial growth metabolism and other life activities. In this paper, based on the mechanism of different mineral electron energy forms and the common and different characteristics of their participation in biochemical reactions, we review different electron carriers and transmission pathways required by microorganisms to obtain extracellular mineral electron energy, and discuss effects of different mineral electronic energy forms on growth metabolism of microorganisms and other life activities. Furthermore, we look forward to new ways for microorganisms to use mineral electronic energy under natural conditions, which can regulate microbial life activities, with elements and energy cycles promoted.