Aerobic vs Anaerobic Bacteria
Aerobic bacteria require oxygen to grow and survive, using it as a final electron acceptor in their metabolic processes. In contrast, anaerobic bacteria can grow and survive in the absence of oxygen, using alternative electron acceptors such as nitrate or sulfate. This fundamental difference in oxygen requirements influences the types of environments where these bacteria can thrive.
6 Key excerpts on "Aerobic vs Anaerobic Bacteria"
eBook - ePub- Luis M. de la Maza, Marie T. Pezzlo, Cassiana E. Bittencourt, Ellena M. Peterson(Authors)
- 2020(Publication Date)
- ASM Press(Publisher)
...27 Introduction to Anaerobic Bacteria Anaerobic bacteria are ubiquitous: they are commonly found in the environment, in soil as well as in water, and are also a major component of the indigenous microbiota of animals. In humans, they can outnumber aerobic organisms by as much as 1,000:1. Anaerobes are commonly found on the mucosal surfaces of the gastrointestinal tract, the genitourinary tract, and the upper respiratory tract. They are also part of the microbiota of the skin. Under normal conditions, these organisms do not cause disease. However, the heavily colonized surfaces are portals of entry into tissues and the bloodstream. When anaerobic bacteria gain access to normally sterile body sites, they can become opportunistic pathogens and cause serious, sometimes fatal, infections. Observations such as a foul odor, gas in the specimen, and black discoloration of blood‐containing exudates can provide helpful clues to the presence of an anaerobic infection. Multiple bacteria and unique bacterial morphology in direct Gram stains of clinical material can also provide presumptive evidence of the presence of anaerobes. Since most anaerobic infections arise in close proximity to mucosal surfaces, knowledge of the normal microbiota of these sites provides critical information about the presumptive identification of the infectious agents. This is important because most anaerobic infections are usually polymicrobic, with a mixture of various aerobic, facultative, and anaerobic organisms. The presence of mixed bacteria, along with the slower growth of the anaerobes, often makes isolation and identification of significant organisms a difficult and time‐consuming process. SPECIMEN COLLECTION AND TRANSPORT Specimen collection and transport are critical factors in successful laboratory isolation of anaerobic pathogens...
eBook - ePub- Volodymyr Ivanov(Author)
- 2020(Publication Date)
- CRC Press(Publisher)
...22 Anaerobic and Anoxic Biotreatment of Waste Oxygen and Energy Generation The evolution of an anaerobic to an aerobic atmosphere on Earth resulted in the creation of the following: anaerobic (living without oxygen) microorganisms facultative anaerobic (living under either anaerobic or aerobic conditions) microorganisms microaerophilic (living under low concentrations of dissolved oxygen) microorganisms obligate aerobic (living only in the presence of oxygen) microorganisms Anaerobes produce energy from the following: fermentation (destruction of organic substances without an external acceptor of electrons) anaerobic respiration using electron acceptors such as N O 3 −, N O 2 −, Fe 3+, SO 4 2 −, and CO 2 anoxygenic (H 2 S → S) photosynthesis Microaerophiles and aerobes produce energy from the following: aerobic oxidation of organic matter oxygenic photosynthesis The sequence of increasing the production of biological energy per mole of transferred electrons is as follows: fermentation → CO 2 respiration (“hydrogenotrophic methanogenesis”) → dissimilative sulfate-reduction → dissimilative iron. reduction (“iron respiration”) → nitrate respiration (“denitrification”) → aerobic respiration. Anaerobic Digestion of Organic Matter There are many applications of anaerobic processes to the treatment of polluted soil, solid waste, and wastewater...
- Rumana Riffat, Taqsim Husnain(Authors)
- 2022(Publication Date)
- CRC Press(Publisher)
...Anaerobic suspended and attached growth processes used for wastewater treatment will be discussed in detail in the later part of this chapter. Anaerobic processes used for the treatment of sludge and biosolids will be discussed in Chapter 12. 11.2 Process chemistry and microbiology Anaerobic waste treatment is a complex biological process involving various types of anaerobic and facultative bacteria. A four-step process can be used to describe the overall treatment. Although the bacteria are represented by separate groups, it is not possible to separate the metabolism of each group. They are interdependent. The anaerobic biotransformation process is illustrated in Figure 11.1. Figure 11.1 Metabolic steps involved in anaerobic biotransformation (adapted from McCarty and Smith, 1986). The numbers represent the different microbial groups. Five groups of bacteria are thought to be involved, each deriving its energy from a limited number of biochemical reactions. They are the following (Novaes, 1986): Fermentative bacteria – This group is responsible for the first two stages of anaerobic conversion, hydrolysis, and acidogenesis. Anaerobic species belonging to the family of Streptococcus and Enterobacter, and to the genera of Clostridium eubacterium are mainly found in this group. Hydrogen-producing acetogenic bacteria – They catabolize sugars, alcohols, and organic acids to acetate and carbon dioxide. These include Syntrophobacter wolinii and Syntrophomonus wolfei. Hydrogen-consuming acetogenic or homoacetogenic bacteria – These bacteria use hydrogen and carbon dioxide to produce acetate...
eBook - ePubNitrogen Cycle
Ecology, Biotechnological Applications and Environmental Impacts
- Jesus Gonzalez-Lopez, Alejandro Gonzalez-Martinez, Jesus Gonzalez-Lopez, Alejandro Gonzalez-Martinez(Authors)
- 2021(Publication Date)
- CRC Press(Publisher)
...Only these bacteria can be defined as true denitrifying and the process, which was formerly considered only possible in anaerobic conditions, can also occur under aerobic conditions. Moreover, a co-respiration process of oxygen and nitrate has been recently proposed as an adaptation for the degradation of toxic nitrogen forms and seems to be present in a wide pattern of natural or artificial environments, such as soil, fresh and marine waters, and wastewater treatment plants. The majority of denitrifying bacteria show a chemoorganotrophic metabolism and are facultative anaerobes (Takaya et al. 2003, Barnard 2005, Knowles 1982, Yang et al. 2015, Marchant et al. 2017). Denitrification is also widely present among fungi where a large number of genera present this metabolic ability (i.e., Aspergillus, Chaetomium, Clonostachys, Fusarium, Penicillium, Trichoderma, and many others) and contribute to the release of the greenhouse gas N 2 O. Most of these fungi are present both as terrestrial and marine species in a wide array of different habitats (Tempesta et al. 2003, Cathrine and Raghukumar 2009, Mouton et al. 2012, Richards et al. 2012 Pasqualetti et al. 2019a, b). The process is split between mitochondria and cytoplasm. Nitrate is reduced to nitrite by nitrate reductase (NAR) and subsequently to nitric oxide by NIR in the mitochondrion; the latter being reduced to nitrous oxide by NOR in the cytoplasm; N 2 O is then excreted. The system functions during anaerobic respiration. Phylogenetic analyses of the genes involved in the process showed that the fungal denitrifying system has a common ancestor with the bacterial equivalent indicating its possible proto-mitochondrial origin. Some fungi have both assimilative and dissimilative NARs. (Maeda et al. 2015, Novinscak et al. 2016, Shoun and Fushinobu 2016). FIGURE 1.8 Denitrification in bacteria and fungi...
eBook - ePubBiomethane
Developments and Prospects
- Sonil Nanda, Prakash K. Sarangi, Sonil Nanda, Prakash K. Sarangi(Authors)
- 2022(Publication Date)
- Apple Academic Press(Publisher)
...Nevertheless, in the absence of sufficient concentrations of methanogenic bacteria or if unfavorable environmental factors slow down, the acids are not consumed as quickly as acid formers produce them, thereby increasing the concentration of volatile acids. An increase in acid demand thus means that the formers of methane will not follow the acid formers (McCarty et al., 1964). Table 2.1 indicates both merits and demerits of anaerobic digestion strategies. TABLE 2.1 Merits and Demerits of the Anaerobic Digestion Processes Merits Demerits Less solid development, i.e., around 3–5 times less than in aerobic processes High energy use, commonly correlated with a powerful pumping station, which results in very high running costs Fewer land demands Less construction costs Methane has a high heating value Possibility of storing the biomass for many months, without reactor feeding Tolerance against heavy organic feed Many applications Less intake of nutrients A significant range of substances are subject to inhibition by anaerobic microorganisms In the absence of suitable seed sludge, plant start-up may be sluggish It normally requires some sort of post-treatment Anaerobic digestion biochemistry and microbiology are complicated, and further studies are still needed Possible generation of unpleasant smells even though they are controllable Possible production of bad looking effluents Insufficient degradation of ammonia, phosphorus A significant range of substances are subject to inhibition by anaerobic microorganisms In the absence of suitable seed sludge, plant startup may be. sluggish Source: Lettinga et al. (1996); Chernicharo and Campos (1995); von Sperling (1995). 2.3 TYPE OF BIOREACTOR FOR ANAEROBIC DIGESTION The nature of systems for handling biological wastewater is in the capacity of the microorganisms concerned to use biodegradable organic compounds to turn them into by-products that can be extracted from the treatment network...
eBook - ePub- Rattan Lal(Author)
- 2017(Publication Date)
- CRC Press(Publisher)
...Anaerobic Processes Paul A. McDaniel Daniel G. Strawn University of Idaho, Moscow, Idaho, U.S.A. Abstract Anaerobic processes in soils occur when available molecular oxygen concentrations are limited. These processes include a myriad of biogeochemical processes that typically occur in soils that are saturated with water for extended periods. Anaerobic processes result in soil characteristics such as increased organic matter content, changes in biological activity, and formation of redoximorphic features. INTRODUCTION Availability of oxygen (O 2) in soils, or lack thereof, has a profound effect on soil biogeochemical processes. When molecular O 2 is absent in soils or present in very small quantities, anaerobic biological processes occur that create distinct soil chemical properties and morphological features as compared to aerobic soils. ANAEROBIC CONDITIONS AND O 2 AVAILABILITY A common means of assessing O 2 status of soils is measuring redox potential (E h). E h can be thought of as a measure of the electron activity of a system. [ 1 ] E h can be predicted using theoretical relationships or measured directly in the soil using a redox electrode. The exact relationship between O 2 and E h within soils is dependent upon a number of specific soil properties; the general relationship illustrated in Fig. 1 shows that as O 2 levels in soils decline, E h decreases (provided biological respiration is occurring). Levels of O 2 availability in soils are generally described using three categories (Fig. 2): • Oxic or aerobic soils—O 2 is readily available; E h range of ∼300–800 mV at pH 7. • Suboxic soils—limited O 2 availability; E h values of ∼100–300 mV at pH 7. • Anoxic or anaerobic soils—O 2 is absent or otherwise unavailable to organisms (may occur in localized zones of the soil); E h values less than ∼100 mV at pH 7. It is important to note that in soils, anaerobic conditions may occur on a microscale...
