Heterotrophs

10 Key excerpts on "Heterotrophs"

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  The Autotrophic Biorefinery

  Raw Materials from Biotechnology

  • Robert Kourist, Sandy Schmidt, Robert Kourist, Sandy Schmidt(Authors)
  • 2021(Publication Date)
  • De Gruyter

    (Publisher)

  The term first appeared in literature in 1946 as a part of an effort to classify microorganisms by their mode of nutrition. By definition, a heterotrophic organism requires an external supply of various essential metabolites due to its incapability of self-synthesizing; thus, it depends on sources other than itself for nutrition and energy [1]. Heterotrophic organisms represent, by far, the largest diversity in our ecosys-tem, comprising approximately 95% of all known and described living organisms. The bacterium Escherichia coli ( E. coli ) and the yeast Saccharomyces cerevisiae ( S. cerevisiae ), two widely utilized biotechnological production organisms, are promi-nent examples of Heterotrophs. Most Heterotrophs are considered to be organohe-terotrophs that derive their carbon from an organic material. The oxidation of these compounds leads to adenosine triphosphate (ATP) synthesis, which provides energy and generates the necessary precursors for various synthetic processes in the micro-organisms [2]. https://doi.org/10.1515/9783110550603-001 The second term, autotrophy, translates to self-feeding – from the Greek word for self – autos-. In contrast to heterotrophy, it is a unique form of metabolism that is found throughout the tree of life and is, in fact, the basis for life as we know it as the main producers in ecological pyramids are autotrophs. Despite the lesser known diversity of autotrophic organisms, the biomass distribution of plants alone on our planet is estimated to be ~ 450 gigatons of carbon (Gt C) out of a total ~ 550 Gt C in the biosphere [3]. Autotrophs are capable of synthesizing complex organic material by employing only inorganic compounds that are present in their natural surround-ings. By virtue of this ability, such organisms are considered to be the “ producers ” in any food chain, implying the reliance of life in its entirety on them. Autotrophs are generally categorized into photoautotrophs and chemoautotrophs.

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  The Origin and Nature of Life on Earth

  The Emergence of the Fourth Geosphere

  • Eric Smith, Harold J. Morowitz(Authors)
  • 2025(Publication Date)
  • Cambridge University Press

    (Publisher)

  15 Although defined in terms of the input/output characteristics of individual organisms’ biochemical networks, this criterion is ultimately a distinction among ecological roles that organisms take. Autotrophic organisms are ecosystems-unto- themselves, while heterotrophic organisms require an ecological embedding to define their 13 Many of these reactions are redox disproportionations: reactions that begin with carbon at formal oxydation states near zero and convert it to mixtures of more oxidized and more reduced carbon species [856, 857]. 14 An example is the delivery of large stores of sugar in fruits by flowering plants. 15 A broad miscellaneous set of organisms are categorized as “mixotrophs” [481], because (facultatively or obligately) they fix some carbon themselves and obtain some other carbon from the environment. We will argue (Chapter 4) that many autotrophs have a metabolic architecture more similar to mixotrophs than has been supposed. 2.3 Bioenergetic and trophic classification of metabolisms 49 biochemical function. For most Heterotrophs, the environments in which they can survive and grow are restricted. Another way to think about the distinction between autotrophy and heterotrophy is that each defines a particular relation between biochemistry and genomic control under the influence of natural selection. Autotrophs have the entire inventory of metabolic functions that they require under the control of a genome that undergoes selection for survival in each generation. Thus the components of the metabolic machinery are by and large 16 fil- tered for mutual compatibility in each generation. Ecosystems composed of Heterotrophs that jointly account for the whole biosynthetic network partition the problem of metabolic control among multiple genomes, which undergo selection autonomously from one another in the generations of different species.

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  Ecology

  Principles and Applications

  • J. L. Chapman, M. J. Reiss(Authors)
  • 1998(Publication Date)
  • Cambridge University Press

    (Publisher)

  Finally, we will see whether there are any rules governing the trophic levels and feeding relationships observed in nature. 11.2 Autotrophs Autotrophs, as we briefly discussed in Chapter 2, are organisms that literally 'feed themselves'. Unlike Heterotrophs, they do not require organic compounds as their source of energy. Autotrophs can be divided into two groups, the photoautotrophs and the chemoautotrophs, and we will look at each of these groups in turn. The autotrophs are sometimes also referred to as producers. This is because they manufacture or produce the organic molecules on which all other organisms depend for their source of energy. 11.2.1 Photoautotrophs The autotrophs with which we are most familiar are the photoautotrophs or photosynthetic organisms. As their name suggests, photoautotrophs obtain their energy from light: the Sun. The organisms best known to us as photoautotrophs are, of course, plants. Most ecologists accept a five kingdom classifi- cation of life (Margulis & Schwartz, 1982). Under this classification, from which viruses are excluded, organisms are classified into the following five king- doms: Prokaryotae (unicellular), Protoctista (eukary- otes that do not fit into the other kingdoms: often unicellular), Plantae (multicellular eukaryotes with photosynthetic nutrition), Fungi (multicellular eukaryotes with hyphae and living saprotrophically or parasitically) and Animalia (multicellular eukary- otes lacking cell walls and living heterotrophically). Of these five kingdoms, three show photoauto- trophic nutrition. Almost all species of plants are photoautotrophs, the exceptions being parasitic plants such as broomrapes (Orobanche spp.) and dodders (Cuscuta spp.) (see Box 2, p. 8).

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  Soil Microbial Associations

  Control of Structures and Functions

  • V. Vancura, F. Kunc(Authors)
  • 2012(Publication Date)
  • Elsevier Science

    (Publisher)

  The heterotrophi c organisms utilize, transform a nd decompose this primarily produced organic matter. 17 ι It is usefu l to consider the ecosystem s as comprising the following c o n-stituents : (1) inorganic a nd organic component s of the abiotic environment ; (2) climatic regimens , representing the driving variables of the ecosystems ; (3) producers or autotrophs , i.e., green p l a n ts producing the p r i m a ry organic matter; (4) macroconsumers , or phagotrophs , i.e., animal feeding on p r i m a ry o r g a n ic matter or on other organisms a nd belonging, therefore , to the heterot-rophic organisms producing the secondar y organic matter; (5) microconsumers , saprotrophs or osmotrophs , a l so belonging to the g r o up of Heterotrophs a nd represente d mainly by microorganisms (bacteria , actinomycetes , micromycetes a nd protozoa) , utilizing, decomposing a nd transforming complicated organic compounds of b o th biotic a nd abiotic origin, releasing s o me constituent s a nd simple mineral substance s a nd m a k i ng t h em available for f u r t h er cycling of matter, a nd a l so producing secondar y organic matter. The ecosystem is the basic structura l a nd functional unit of the biosphere , forming intricate food c h a i ns a nd food pyramids. The holistic approach to ecosystem considers the concept s of (1) energy flows, (2) mineral cycling, (3) w a t er cycling, (4) food c h a i ns arid (5) species d i v e r s i t y. It enables us to under-stand, classify, q u a n t i f y, utilize a nd manage ecosystem s on b o th t e r r i t o r i al (local, regional, continenta l a nd g l o b a l) a nd organizationa l (agricultura l enter-prise, county a nd country) levels. Microorganisms decomposing b o th the p r i m a ry a nd secondar y organic m a t-ter in the ecosystem s posses s o me specific features , which m a ke t h em indispens -a b l e.

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  Ecology and Applied Environmental Science

  • Kimon Hadjibiros(Author)
  • 2013(Publication Date)
  • CRC Press

    (Publisher)

  These have the fundamental capability to produce synthetic organic matter using inorganic matter along with solar energy. Plants are the producers in terrestrial ecosystems, while in aquatic ecosystems they are mostly algae. • Consumers are heterotrophic-chemosynthetic organisms, apart from bacteria and fungi. They are only capable of composing organic matter after obtaining carbon and energy from the producers. Energy ECOSYSTEM Energy Chemical element Chemical element Chemical element Figure 4.1 Energy and matter flow. (From Hadjibiros, K. (2007). Ecology. Ecosystems and Environmental Protection, 3rd edition. Symmetria, Athens (in Greek). With permission.) Organisation at the Ecosystem Level 43 © 2010 Taylor & Francis Group, LLC • Decomposers are the bacteria and fungi which are consumers in essence but execute a special function in the ecosystems. Their role is to break down dead organic matter to inorganic compounds, which thus become available again for producers’ consumption. A series of species, each one of which constitutes food for the next (Chapter 3, Section 3.4.3), is described as a food chain. Often, food chains are interconnected, since many ecosystem organisms belong to more than one food chain. Thus, trophic webs, which can be divided in trophic levels, are created. The first trophic level contains plants or algae, the second one herbivores or zooplankton, the third one the first carnivore animals, the fourth the second carnivore animals etc. Omnivorous animals are placed in more than one trophic level. During energy flow from one trophic level to another, the available energy is reduced (Figure 4.2). In each step, a small part of the incoming energy equivalent of food is discarded as waste, while the main part is used for the energy needs of the respective level; the bigger part of it is discarded as heat through respiration, while the rest is integrated as chemical energy to the produced biomass.

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  Agroecology

  The Ecology of Sustainable Food Systems, Third Edition

  • Stephen R. Gliessman(Author)
  • 2014(Publication Date)
  • CRC Press

    (Publisher)

  149 13 So far we’ve discussed agroecosystems as if they are based entirely on the growth of plants. Although plants are indeed the foundation for growing our food, we can’t ignore the fact that animals—and other non-photosynthesizing organisms, like insects and fungi and some protists—are both abso-lutely essential elements of agroecosystems and factors that must be taken into account in managing these systems. In Chapter 2 we defined these organisms as Heterotrophs , or all organisms that meet their nutritive and energetic needs by consuming other organisms. Various types of Heterotrophs were discussed as biotic factors of the environment in Chapter 11. In this context, we looked at the interactions between Heterotrophs and other organisms, and our interest was in categorizing these interac-tions and distinguishing them by type, rather than in examin-ing the Heterotrophs themselves. In this chapter, we shift our frame of reference to the heterotrophic organisms, looking at these organisms directly rather than as special kinds of biotic factors. This results in two related but distinct discussions. In Heterotrophs as Factors Affecting Crop Plants , we focus on Heterotrophs as factors of the environment but give atten-tion to the organisms involved and the particular effects they have on crop plants. In Animals as Resources in Agricultural Production , we discuss animals as organisms from which humans derive food and which, like crop plants, confront an environment made up of separate factors. Heterotrophs AS FACTORS AFFECTING CROP PLANTS As described in Chapter 2, heterotrophic organisms play important roles in ecosystem structure and function. In their roles as consumers, either as primary consumers of plants or secondary consumers of other animals or animal products, they are essential elements in energy flow, nutrient cycling, and the regulation of the numbers of other organisms, especially plants.

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  A Natural History of California

  Second Edition

  • Allan A. Schoenherr(Author)
  • 2017(Publication Date)
  • University of California Press

    (Publisher)

  In order to produce glucose, the above equation is balanced by multiplying it through by a factor of six. Actually, it is simplest to view the organisms of an ecosystem in terms of two rather than three categories. The first category, called autotrophic (self-nourishing), contains organ-isms that produce their own food. The second, called heterotrophic , contains organisms that do not produce their own food. As far as an ecosys-tem is concerned, there is little difference between consumers and decomposers. They all eat one another. In fact, they compete with one another for a fair share of the same food. When humans put food into a freezer, they are putting their share where microorganisms can’t get to it. Microorganisms, on the other hand, get their share by producing foul odors or toxins that dis-courage humans from eating the food. A simple ecosystem might have only two kinds of organisms. A sewer outflow, for exam-ple, might have only algae (autotrophic) and bacteria (heterotrophic). The important thing is that one organism makes the food, and the other recycles matter by consuming it. The nonliving components of an ecosystem include matter that is cycled and the energy that powers it. Energy in an ecosystem is repre-sented by heat and light, the ultimate source of which is the sun. Fluctuations of these two energy forms have a profound influence on the system. The matter in a system may be thought of in terms of pure elements such as carbon, hydrogen, oxygen, nitrogen, and phosphorus. These elements may combine to form various materials such as water (H 2 O), carbon dioxide (CO 2 ), carbohydrate (CH 2 O), nitrate (NO 3 ), and phosphate (PO 4 ). A simple way to describe the nonliving components of an ecosystem is to lump all these factors into five categories: light, heat, air, water, and soil (minerals). If one fac-tor is deficient, it becomes ecologically limiting and exerts a powerful influence on the ecosys-tem.

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  Microbiology

  • Dave Wessner, Christine Dupont, Trevor Charles, Josh Neufeld(Authors)
  • 2020(Publication Date)
  • Wiley

    (Publisher)

  Autotrophs assimilate carbon from inorganic sources, primarily CO 2 , into organic molecules through a process known as carbon fixation. Autotrophic organisms, includ- ing plants and algae, generate most of Earth’s biomass. Addi- tionally, as we saw in Section 1.3, these autotrophic organisms generally are responsible for the oxygen-rich atmosphere that we have today. It’s worth noting, too, that many bacteria and archaea exhibit remarkable metabolic diversity. Some auto- trophs can use heterotrophy when suitable organic carbon sources are available to augment the more energy-intensive process of fixing CO 2 . This is referred to as “mixotrophy.” Many cyanobacteria are mixotrophs. They have a competitive advantage over obligate heterotrophic bacteria, which cease growing in the absence of organic carbon, and obligate auto- trophic plants and algae, which do not grow in the absence of sufficient light. Another example is the mixotrophic Gram- negative bacterium Rhodospirillum rubrum (Microbes in Focus 6.1). Because of this metabolic diversity, we see micro- organisms growing in every conceivable habitat on Earth. 6.1 Fact Check 1. From what sources can organisms acquire electrons? 2. What is the difference between an organic and inorganic compound? 3. Explain what the term chemoorganoautotrophy means. Why does this nutritional strategy not exist? 4. Describe chemotrophs, phototrophs, organotrophs, lithotrophs, Heterotrophs, and autotrophs. 5. How might understanding the natural growth requirements of a microorganism help a researcher? 176 CHAPTER 6 Metabolism thermodynamics states that energy is always conserved; it cannot be created or destroyed. However, energy can be con- verted from one form into another. The second law of ther- modynamics states that in all energy exchanges, where no energy enters or leaves the system, the potential energy of the resulting state will always be less than that of the initial state.

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  Communities and Ecosystems

  Linking the Aboveground and Belowground Components

  • David A. Wardle(Author)
  • 2013(Publication Date)
  • Princeton University Press

    (Publisher)

  7 CHAPTER TWO The Soil Food Web Biotic Interactions and Regulators In any food web, the primary drivers are the autotrophs, which are responsible for determining the amounts of car-bon that enter the system. However, in the case of the de-composer food web, the heterotrophic organisms are ulti-mately responsible for governing the availability of nutrients required for plant productivity. As a result, the plant and decomposer subsystems are in an obligate mutualism with one another, with each of the two components carrying out processes required for the long-term maintenance of the other. Those organisms that comprise the decomposer food web span several orders of magnitude in terms of body size, and consist of the microflora (bacteria, fungi), microfauna (body width less than 0.1 mm, e.g., nematodes, protozoa), mesofauna [body width 0.1–2.0 mm, e.g., enchytraeids, mi-croarthropods (mites, springtails)], and macrofauna (body width greater than 2 mm, e.g., earthworms, termites, milli-pedes). The primary consumers consist of the microflora, which are uniquely capable of directly breaking down com-plex carbohydrates in plant-sourced detritus and mineraliz-ing the nutrients contained within. The secondary and high-er-level consumers, i.e., the soil fauna, feed upon the microbes and each other, and therefore have immense im-portance in governing these microbial processes. Because of the vast ranges of body sizes of soil fauna, they determine soil processes at a range of spatial scales (fig. 2.1), and for C H A P T E R 2 8 F igure 2.1. Structure of the soil food web. Only major groups of organisms and well-established linkages are shown. Arrows indicate direction of ener-gy flow. The microfood-web, litter transformer, and ecosystem engineer cat-egories are derived from Lavelle et al.

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  eBook - ePub

  Fundamentals of Soil Ecology

  • David C. Coleman, D. A. Crossley Jr., D. A. Crossley, Jr.(Authors)
  • 2004(Publication Date)
  • Academic Press

    (Publisher)

  4 Secondary Production: Activities of Heterotrophic Organisms—The Soil Fauna

  INTRODUCTION

  Animals, the other group of major Heterotrophs in soil systems, exist in elaborate food webs containing several trophic levels. Some soil animals are true herbivores, because they feed directly on roots of living plants, but most subsist upon dead plant matter, microbes associated with dead plant matter, or a combination of the two. Still others are carnivores, parasites, or top predators. Actual heterotrophic production by the soil fauna is poorly known, because turnover of the faunal biomass, feeding rates, and assimilation efficiencies are difficult to assess. Estimates of biomass of soil animals are not common, and knowledge of the rates of energy or material transfer in food webs is fragmentary (Moore and de Ruiter, 1991 ; 2000 ). Analyses of food webs in the soil have emphasized numbers of the various organisms and their trophic resources. Analysis of the structure of these food webs reveals complex structures with many “missing links” poorly described (

  Walter et al ., 1991

  ; Scheu and Setälä, 2002 ). Communities of soil fauna offer opportunities for studies of phenomena such as species interactions, resource utilization, or temporal and spatial distributions.

  Animal members of the soil biota are numerous and diverse. The array of species is very large, including representatives of all terrestrial phyla. Many groups of species are poorly understood taxonomically, and details of their natural history and biology are unknown. For the microarthropods (discussed later in this chapter), only about 10% of populations have been explored, and perhaps only 10% of species described (

  André et al ., 2002

  ). Protection of biodiversity in ecosystems clearly must include the rich pool of soil species.

  Soil ecologists cannot hope to become experts in all animal groups. When research focuses at the level of the soil ecosystem, two things are required: the cooperation of zoologists and the lumping of animals into functional groups. These groups are often taxonomic, but species with similar biologies are grouped together for purposes of integration (

  Coleman et al ., 1983

  ; 1993 ;

  Hendrix et al

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