China
Africa
Explore chapters and articles related to this topic
Components of Nutrition
Published in Christopher Cumo, Ancestral Diets and Nutrition, 2020
Humans and other animals must consume food for energy because, Chapter 3 emphasizes, they are heterotrophs, organism that cannot manufacture energy and nutrients, except for vitamin D in the presence of sunlight. Heterotrophs contrast with autotrophs—plants, algae, and photosynthetic bacteria—which use sunlight for energy. Heterotrophs use food to fuel the chemical reactions that sustain life. Absent food’s energy, cessation of these reactions causes death. The fact that life requires energy raises the issue of quantification: How much energy does the body need for maintenance, growth, and reproduction? This question is difficult to answer given that several factors influence requirements.
Organic Matter
Published in Michael J. Kennish, Ecology of Estuaries Physical and Chemical Aspects, 2019
Green plants, via photosynthesis, supply most of the organic carbon production of estuaries. Photosynthetic bacteria, although potentially important in polluted and eutrophic systems, account for only a minor portion of the total organic carbon produced. Sulfate-reducing bacteria are obligate anaerobes (growing only in environments devoid of oxygen) frequently encountered at the upper edge of the reduced zone of tidal mudflat sediments and in anaerobic water masses. Chemosynthetic bacteria appear to be intermediate between autotrophs and heterotrophs,64 responsible for what is termed “secondary primary production”. Heterotrophs participate directly in carbon cycling by ingesting organic matter, converting plant organic carbon into animal organic carbon, and respiring or excreting metabolites and ultimately releasing elements subsequent to death and microbial decay.292 Various pathways of carbon transformation exist; however, carbon fixed by autotrophs ultimately enters abiotic carbon pools through respiration (CO2), mortality and defecation (POC), and secretion and degradation (DOC).24
Revisioning Cellular Bioenergetics
Published in Aruna Bakhru, Nutrition and Integrative Medicine, 2018
Researchers articulate that the transfer of photosensitized electrons originating “from excited chlorophyll-type molecules is widely hypothesized to be a primitive form of light-to-energy conversion that evolved into photosynthesis” (Xu et al., 2014, p. 394). This, in concert with the fact that sunlight-derived photons of red light have resided within nearly every mammalian tissue throughout evolution, lends credence to the notion that mammalian life harbors conserved molecular mechanisms designed to harness photonic energy (Xu et al., 2014). Fundamentally, this study reveals that animals are not just glucose-burning biomachines, but are light-harvesting hybrids. Technically, that knocks us out of the category of heterotrophs into photoheterotrophs.
Blautia—a new functional genus with potential probiotic properties?
Published in Gut Microbes, 2021
Xuemei Liu, Bingyong Mao, Jiayu Gu, Jiaying Wu, Shumao Cui, Gang Wang, Jianxin Zhao, Hao Zhang, Wei Chen
Blautia species are strictly anaerobic, non-motile, 1.0–1.5 × 1.0–3.0 μm in size, usually spherical or oval, and appear in pairs or strands, with most strains being sporeless. The optimum temperature and pH for most Blautia strains are 37°C and 7.0, respectively.11 Some species such as B. producta possess both heterotrophic and autotrophic properties and can use CO, H2/CO2, and carbohydrates as energy sources.34 Carbohydrate utilization experiments have shown that all Blautia strains can use glucose, but different strains showed different abilities to use sucrose, fructose, lactose, maltose, rhamnose, and raffinose (Table 2). The final products of glucose fermentation by Blautia are acetic acid, succinic acid, lactic acid, and ethanol, and the main biochemical tests have revealed negative results for lecithin, lipase, catalase, and indole. The long-chain fatty acids produced by Blautia strains are classified into linearly saturated and monounsaturated types, with C14:0, C16:0, and C16:00 dimethyl acetal fatty acids as the main species. The GC content of Blautia DNA is 37–47 mol%, and the type species of this genus is B. coccoides.11
Neglecting the ecosystemic dimension of life hinders efficient environmental protection from radiation and other hazards
Published in International Journal of Radiation Biology, 2022
Perhaps, the easiest understandable example of collaborative interaction betwen species in ecosystems is the trophic interdependance which promotes bioregeneration: autotrophic photosynthtic species transform inorganic (CO2, minerals, …) into organic matter (mostly carbohydrates) that is used as a food source by heterotrophic animal species, the autotrophs also regenerate the O2, required by the heterotrophs respiration, from the CO2 these later produce whislt oxydising the organic matter that they ingest as food. Thus, the ecosystem features a bioregeneration capacity through an autotrophs-heteroptrophs cycling where the by-products from autotrophs are used by heterotrophs as ressources and vice versa.
The role of iron-oxidizing bacteria in biocorrosion: a review
Published in Biofouling, 2018
Incubation studies are useful for understanding patterns of colonization and succession, but are less informative about the long-term presence of FeOB in corrosion products associated with emplaced steel infrastructure, including shipwrecks. A study of rusticles associated with World War-era II ship wrecks in the Gulf of Mexico showed evidence for biogenic Fe-oxides based on scanning electron microscopy. A gene survey of these rusticles found 16S sequences belonging to Zetaproteobacteria were present in at least one case, although the most widespread and prevalent sequences were associated with putative clades of SRB and sulfur-oxidizing microbes (Little et al. 2017). Additionally, a molecular study of World War II-era of corrosion tubercles in Australia also found the presence of sequences for M. ferrooxydans, in a complex microbial community dominated by methanogens (Usher et al. 2014). Another recent study used 16S gene analysis to compare MS emplaced for eight years at two sites on the coast of China, along with another set of one-month-old samples (Li et al. 2017). In this case Proteobacteria, Firmicutes, and Bacteroidetes were the dominant phyla, with Proteobacteria accounting for 50–80% of the reads in eight of nine samples. OTUs belonging to the Deltaproteobacteria dominated the Proteobacteria, with the majority of these related to known groups of SRBs, with the genera Desulfovibrio and Desulfotomaculum having the highest relative abundances. The Zetaproteobacteria were present in most of the samples, with relative abundances of around 0.5–3%. This stands in contrast to the shorter term colonization studies described above where the presence of Zetaproteobacteria was found to decrease over the course of weeks, in some cases to undetectable levels. A third study, done in France, used a sophisticated reactor system to simulate tidal effects and follow MS corrosion over nine months under conditions where the system was either amended or unamended with organic carbon (Marty et al. 2014). An endpoint analysis (nine months) found Zetaproteobacteria were among the more prevalent phylotypes in corrosion tubercles in the unamended treatments, but were not found in tubercles associated with the organic treatments. This is consistent with the lithoautotrophic metabolism of FeOB, where it is unlikely they could compete with heterotrophs when readily available organic matter is present. Overall, in the Marty et al study (2014), SRB were common to all treatments with the greatest prevalence in the presence of organic amendment. Together, these investigations of long-term corrosion products indicate FeOB can become established as inhabitants of what are presumably quite stable MIC communities.