text: As key players in the carbon cycle, methylotrophs work to reduce global warming primarily through the uptake of methane and other greenhouse gases. In aqueous environments, methanogenic archaea produce 40-50% of the world's methane. Symbiosis between methanogens and methanotrophic bacteria greatly decreases the amount of methane released into the atmosphere.
  This symbiosis is also important in the marine environment. Marine bacteria are very important to food webs and biogeochemical cycles, particularly in coastal surface waters but also in other key ecosystems such as hydrothermal vents. There is evidence of widespread and diverse groups of methylotrophs in the ocean that have potential to significantly impact marine and estuarine ecosystems.  One-carbon compounds used as a carbon and energy source by methylotrophs are found throughout the ocean. These compounds include methane, methanol, methylated amines, methyl halides, and methylated sulfur compounds, such as dimethylsulfide (DMS) and dimethylsulfoxide (DMSO). Some of these compounds are produced by phytoplankton and some come from the atmosphere. Studies incorporating a wider range of one-carbon substrates have found increasing diversity of methylotrophs, suggesting that the diversity of this bacterial group has not yet fully been explored.
  Because these compounds are volatile and impact the climate and atmosphere, research on the interaction of these bacteria with these one-carbon compounds can also help understanding of air-sea fluxes of these compounds, which impact climate predictions. For example, it is uncertain whether the ocean acts as a net source or sink of atmospheric methanol, but a diverse set of methylotrophs use methanol as their main energy source. In some regions, methylotrophs have been found to be a net sink of methanol, while in others a product of methylotroph activity, methylamine, has been found to be emitted from the ocean and form aerosols. The net direction of these fluxes depends on the utilization by methylotrophs.
  Studies have found that methylotrophic capacity varies with the productivity of a system, so the impacts of methylotrophy are likely seasonal. Because some of the one-carbon compounds used by methylotrophs, such as methanol and TMAO, are produced by phytoplankton, their availability will vary temporally and seasonally depending on phytoplankton blooms, weather events, and other ecosystem inputs. This means that methylotrophic metabolism is expected to follow similar dynamics, which will then impact biogeochemical cycles and carbon fluxes.
  Impacts of methylotrophs were also found in deep-sea hydrothermal vents. Methylotrophs, along with sulfur oxidizers and iron oxidizers, expressed key proteins associated with carbon fixation. These types of studies will contribute to further understanding of deep sea carbon cycling and the connectivity between deep ocean and surface carbon cycling. The expansion of omics technologies has accelerated research on the diversity of methylotrophs, their abundance and activity in a variety of environmental niches, and their interspecies interactions. Further research must be done on these bacteria and the overall effect of bacterial drawdown and transformation of one-carbon compounds in the ocean. Current evidence points to a potentially substantial role for methylotrophs in the ocean in the cycling of carbon but also potentially in the global nitrogen, sulfur and phosphorus cycles as well as the air-sea flux of carbon compounds, which could have global climate impacts.
  The use of methylotrophs in the agricultural sector is another way in which they can potentially impact the environment.  Traditional chemical fertilizers supply nutrients not readily available from soil but can have some negative environmental impacts and are costly to produce. Methylotrophs have high potential as alternative biofertilizers and bioinoculants due to their ability to form mutualistic relationships with several plant species. Methylotrophs provide plants with nutrients such as soluble phosphorus and fixed nitrogen and also play a role in the uptake of said nutrients. Additionally, they can help plants respond to environmental stressors through the production of phytohormones. Methylotrophic growth also inhibits the growth of harmful plant pathogens and induces systemic resistance.  Methylotrophic biofertilizers used either alone or together with chemical fertilizers have been shown to increase both crop yield and quality without loss of nutrients.