Molecular Microbiology Research 2024, Vol.14, No.4, 198-207 http://microbescipublisher.com/index.php/mmr 203 5.2 Feedback mechanisms and environmental impacts The interactions between the carbon, nitrogen, and sulfur cycles are influenced by various environmental factors, which in turn affect microbial community composition and function. For example, changes in seawater pH, temperature, and nutrient availability due to anthropogenic activities can alter the physiology and metabolic activities of marine microorganisms, impacting the cycling of these elements (Wasmund et al., 2017). In oxygen minimum zones (OMZs), the expansion of these regions due to climate change can further influence the microbial processes involved in carbon, nitrogen, and sulfur cycling (Figure 3). The microbial community composition and their roles in these cycles vary with depth and oxygen availability, which can have significant implications for the global biogeochemical processes (Long et al., 2021). Figure 3 Global map of oxygen concentrations at 300 m depth (Adopted from Long et al., 2021) 5.3 Influence of microbial diversity on biogeochemical processes Microbial diversity plays a crucial role in the efficiency and stability of biogeochemical cycles. In marine sediments, the diversity of sulfur-transforming microorganisms is linked to their ability to exploit different redox states of sulfur compounds, which in turn affects the cycling of carbon and nitrogen (Wang and Chen, 2024). The vertical distribution of microbial communities in sediments also influences the cycling of these elements, with different microbial groups being more active at various sediment depths (Liao et al., 2021). Additionally, the functional traits of nitrogen-cycling microbial communities in the global ocean are shaped by environmental factors, with functional redundancy ensuring the stability of these processes despite taxonomic variability (Song et al., 2022). This highlights the importance of microbial diversity in maintaining the interconnected cycles of carbon, nitrogen, and sulfur in marine ecosystems. 6 Technological Advances in Studying Marine Microorganisms 6.1 Genomic and metagenomic approaches Genomic and metagenomic approaches have revolutionized our understanding of marine microorganisms and their roles in biogeochemical cycles. These techniques allow researchers to analyze the genetic material of entire microbial communities directly from environmental samples, bypassing the need for cultivation. For instance, metagenomic studies in seagrass meadows have revealed the diversity and metabolic functions of sulfur- and nitrogen-cycling microorganisms, highlighting the dominance of proteobacterial lineages in these processes (Liu et al., 2023). Similarly, genome-resolved metagenomics has provided insights into the metabolic pathways of
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