Hazards from Legionella *
Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse in Routledge Handbook of Water and Health, 2015
The Legionella family (Legionellaceae) is a group of bacteria found in a wide and diverse range of environmental niches, but in particular in fresh water. In the natural environment they are heterotrophs, organisms that feed on complex organic molecules such as amino acids. To source these organic nutrients they have developed a range of different strategies. All of these strategies depend on deriving their nutrients from other organisms in either natural or anthropogenic water systems. As a result they are always part of a complex community in the environment and not easy to isolate as pure cultures in the laboratory. Another important ecological feature is that they have a general growth range of between 20 and 45 °C, but survive at both higher and lower temperatures, though 55 °C is widely regarded as the upper limit for survival (Fields et al., 2002; WHO, 2007, Chs. 1, 2).
Organic Matter
Michael J. Kennish in 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
Components of Nutrition
Christopher Cumo in 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.
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
François Bréchignac
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
David Emerson
As mentioned above, this review will focus on those microbes, primarily bacteria, capable of lithoautotrophic or chemosynthetic growth on ferrous iron, Fe(II); however, it is important to consider the other reactions between microbes and iron as well, since they can be important, and also the source of some confusion. Table 1 presents metabolic reactions relevant to iron that are important for biocorrosion. Lithoautotrophy refers to microbes that gain energy from the oxidation of ferrous iron to ferric iron (Fe(III)), and use this energy to fix carbon dioxide (CO2) as the cell’s primary source of carbon. Heterotrophic Fe-oxidation refers to microbes that actively catalyze the oxidation of Fe(II), but do not gain energy from the process, nor do they fix CO2, instead using organic matter as a carbon and energy source. Exemplars of this process are organisms like Leptothrix discophora and Sphaerotilus natans that produce proteins or enzyme systems that actively catalyze Fe-oxidation, or Mn-oxidation, yet derive no energetic benefit from it (Ghiorse 1984). It is also important to remember that at circumneutral pH, Fe(II) readily oxidizes in the presence of O2 resulting in the spontaneous precipitation of Fe-oxyhydroxides (rust). These oxides can passively adsorb bacteria, thus the mere association of a bacterium with Fe-oxyhydroxides does not prove whether it is catalytically oxidizing Fe(II), or playing a more passive role (Small et al. 1999). One potential example of this are Sediminibacterium spp., a genus within the Bacteroidetes, a bacterial phylum best known for its capacity to grow on complex organic matter (Fernández-Gómez et al. 2013). In the corrosion literature a number of papers refer to Sediminibacterium as a member of the iron-oxidizing bacteria (Wang et al. 2012; Li et al. 2014, 2015; Jin et al. 2015) in part due to the finding of 16S rRNA genes related to this organism being found in DNA extracted from corrosion products. Yet the original description of S. salmoneum, isolated from a eutrophic lake (Qu & Yuan 2008), or subsequent descriptions of newly isolated Sediminibacterium species (Kim et al. 2016), do not make any mention of the capacity to either oxidize Fe(II), or use it as a sole electron donor. Additional issues arise when, in the course of laboratory experiments, cells are grown with compounds like ferrous citrate, where citrate may serve as a carbon/energy source, and it can then be difficult to assess if oxidation of Fe(II) is actually catalyzed by the bacteria or occurring spontaneously (Xu et al. 2007; Liu et al. 2017).
Related Knowledge Centers
- Animal
- Autotroph
- Bacteria
- Carbon Dioxide
- Microbiology
- Primary Nutritional Groups
- Chemotroph
- Photoheterotroph
- Sunlight
- Photoautotrophism