Housekeeping in the Hydrosphere: Microbial Cooking, Cleaning, and Control under Stress

Abstract

Who’s cooking, who's cleaning, and who's got the remote control within the waters blanketing Earth? Anatomically tiny, numerically dominant microbes are the crucial “homemakers” of the watery household. Phytoplankton’s culinary abilities enable them to create food by absorbing sunlight to fix carbon and release oxygen, making microbial autotrophs top-chefs in the aquatic kitchen. However, they are not the only bioengineers that balance this complex household. Ubiquitous heterotrophic microbes including prokaryotic bacteria and archaea (both “bacteria” henceforth), eukaryotic protists, and viruses, recycle organic matter and make inorganic nutrients available to primary producers. Grazing protists compete with viruses for bacterial biomass, whereas mixotrophic protists produce new organic matter as well as consume microbial biomass. When viruses press remote-control buttons, by modifying host genomes or lysing them, the outcome can reverberate throughout the microbial community and beyond. Despite recognition of the vital role of microbes in biosphere housekeeping, impacts of anthropogenic stressors and climate change on their biodiversity, evolution, and ecological function remain poorly understood. How trillions of the smallest organisms in Earth’s largest ecosystem respond will be hugely consequential. By making the study of ecology personal, the “housekeeping” perspective can provide better insights into changing ecosystem structure and function at all scales.

Fresh terrestrial detritus fuels both heterotrophic and autotrophic activities in the planktonic food web of a tropical reservoir: a mesocosm study

“…phytoplankton) stimulation by fresh terrestrial detritus inputs. Even though it is not straightforward to distinguish which mechanism most affects the trophic chain production (microbial loop, primary production or direct zooplankton consumption of detritus), it is well stablished that heterotrophic procaryotes are the central link to life cycle in aquatic systems (Biddanda et al, 2021). Nonetheless, it is clear that they take terrestrial detritus into metabolism in aquatic ecosystems fueling carbon balance and flow (Cole et al, 1994;Pace et al, 2004).…”

Bacterial catabolism of membrane phospholipids links marine biogeochemical cycles

“…The microbial loop, which increases the efficiency of marine food webs through the utilization of dissolved organic matter (DOM), unifies a broad diversity of oceanic microbes including phototrophic cyanobacteria and heterotrophic bacteria and archaea (1)(2)(3)(4)(5). While intensively studied, it is still not fully understood how all available nutrients are shared between microbes, especially how individual nutrient cycles relate to one another.…”

Plankton Genes and Extracellular Organic Substances in the Ocean

“…Rapid progress is being made cataloguing the genes of the pelagic ecosystem, as well as discovering both their roles in producing proteins, and ultimately, via enzymes, of polysaccharides and lipids. Moreover, as Biddanda et al (13) (2021) pointed out, viruses "flip" (i.e. change and transfer) the genes between prokaryotic microbes they infect ( 14) (Chiura, 1997), with the outcomes likely reverberating through the ocean microbial community.…”