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Author: Afonso Cesar Rezende de Souza
Publisher:
ISBN:
Category :
Languages : en
Pages : 392
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Book Description
The respective kinetics of bacterial leucine aminopeptidase and [beta]-glucosidase activities were investigated to improve understanding of factors controlling activity and hydrolytic capacity in estuarine organic-poor sands. Depth distributions of enzyme activity and bulk organic matter content were determined in sediments of Aransas Bay and Copano Bay Texas, to investigate enzyme dynamics as related to the geochemical properties of the sediment. Vertical profiles of activity in sediment showed that the enzymes were more active at the surface and that the potential hydrolysis rate of leucine aminopeptidase was higher than that of [beta]-glucosidase. Vertical patterns of enzyme activity correlated (weakly) with variations in sediment organic matter (TOC, TN, and carbohydrates) content. Enrichments of sediment samples with monomeric organic compounds and inorganic nutrients did not affect leucine aminopeptidase and [beta]-glucosidase activities in short- and long-term incubations. Enzyme activity was independent of nutrient availability and suggested that microbial communities were not nutrient-limited. Time-course assays of bacterial hydrolysis of TOC, TN, and carbohydrates provided information about how substrate limitation may affect enzyme activity. Positive correlations between bulk TOC and TN content and enzyme activity indicated enzyme dependence on polymeric substrate content. Induction of enzyme activity after sediment enrichments with specific labile compounds confirmed the importance of available organic substrate to enzyme hydrolysis efficiency. A kinetic approach established the occurrence of enzyme inhibition and its effects on enzyme hydrolytic capacity. The addition of a specific-enzyme substrate to sediment samples modified enzyme parameters and indicated that a substrate-reversible type of inhibitor could reduce enzyme hydrolytic capacity. The addition of polyphenol, as a natural inhibitor of enzyme activity, to the sediment resulted in a concomitant reduction of leucine aminopeptidase activity and ammonium regeneration rate, and thus demonstrated a close coupling between enzyme activity and sediment ammonium regeneration. These research results demonstrate the dynamic nature of the hydrolytic enzymes, provide information about the mechanisms of induction and inhibition of activity, and demonstrate some implications of reducing the hydrolytic capacity to organic matter decomposition and nutrient regeneration rates.
Author: Afonso Cesar Rezende de Souza
Publisher:
ISBN:
Category :
Languages : en
Pages : 392
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Book Description
The respective kinetics of bacterial leucine aminopeptidase and [beta]-glucosidase activities were investigated to improve understanding of factors controlling activity and hydrolytic capacity in estuarine organic-poor sands. Depth distributions of enzyme activity and bulk organic matter content were determined in sediments of Aransas Bay and Copano Bay Texas, to investigate enzyme dynamics as related to the geochemical properties of the sediment. Vertical profiles of activity in sediment showed that the enzymes were more active at the surface and that the potential hydrolysis rate of leucine aminopeptidase was higher than that of [beta]-glucosidase. Vertical patterns of enzyme activity correlated (weakly) with variations in sediment organic matter (TOC, TN, and carbohydrates) content. Enrichments of sediment samples with monomeric organic compounds and inorganic nutrients did not affect leucine aminopeptidase and [beta]-glucosidase activities in short- and long-term incubations. Enzyme activity was independent of nutrient availability and suggested that microbial communities were not nutrient-limited. Time-course assays of bacterial hydrolysis of TOC, TN, and carbohydrates provided information about how substrate limitation may affect enzyme activity. Positive correlations between bulk TOC and TN content and enzyme activity indicated enzyme dependence on polymeric substrate content. Induction of enzyme activity after sediment enrichments with specific labile compounds confirmed the importance of available organic substrate to enzyme hydrolysis efficiency. A kinetic approach established the occurrence of enzyme inhibition and its effects on enzyme hydrolytic capacity. The addition of a specific-enzyme substrate to sediment samples modified enzyme parameters and indicated that a substrate-reversible type of inhibitor could reduce enzyme hydrolytic capacity. The addition of polyphenol, as a natural inhibitor of enzyme activity, to the sediment resulted in a concomitant reduction of leucine aminopeptidase activity and ammonium regeneration rate, and thus demonstrated a close coupling between enzyme activity and sediment ammonium regeneration. These research results demonstrate the dynamic nature of the hydrolytic enzymes, provide information about the mechanisms of induction and inhibition of activity, and demonstrate some implications of reducing the hydrolytic capacity to organic matter decomposition and nutrient regeneration rates.
Author: Ryszard J. Chrost
Publisher: Springer Science & Business Media
ISBN: 146123090X
Category : Science
Languages : en
Pages : 333
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Book Description
Organic matter in aquatic environments consists mostly of large compounds which cannot be taken up and utilized directly by microbial cells. Prior to incorporation, polymeric materials undergo degradation by cell-bound and extracellular enzymes produced by these microbes; in fact, such enzymatic mobilization and transformation is the key process which regulates the turnover of organic as well as inorganic compounds in aquatic environments. This volume brings together studies on enzymatic degradation processes from disciplines as diverse as water and sediment research, bacterial and algal aquatic ecophysiology, eutrophication, and nutrient cycling and biogeochemistry, in both freshwater and marine ecosystems. Its scope extends from fundamental research exploring the contribution of microbial enzymatic processes to whole ecosystem functioning to practical applications in water biotechnology. The first comprehensive publication providing an overview of this emerging field of enzymology, Microbial Enzymes in Aquatic Environments will be of great interest to ecologists and microbiologists alike.
Author: Maria Montserrat Sala
Publisher: Frontiers Media SA
ISBN: 2889630048
Category :
Languages : en
Pages : 159
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Book Description
Microbial extracellular enzymes are fundamental to the cycling of elements in aquatic systems. The regulation of these enzymatic reactions in oceans, lakes and streams is under complex multiple control by environmental factors and the metabolic capacities of different taxa and communities. While the environmental control of enzyme-mediated processes has been investigated for over 100 years, in recent years tremendous progress in techniques to characterize the metabolic potential of microbial communities (“omics” techniques) has been made, such as high-throughput sequencing and new analytical algorithms. This book explores the controls, activities, and biogeochemical consequences of enzymes in aquatic environments. It brings together experimental studies and fieldwork conducted with natural microbial communities in marine and freshwater ecosystems as well as physiological, biochemical and molecular studies on microbial communities in these environments, or species isolated from them. Additionally, the book contributes to the ongoing debate on the impact of anthropogenic climate change and pollution on microbes, extracellular enzymes and substrate turnover.
Author: Abigail Van Buren Barrett
Publisher:
ISBN:
Category : Biogeochemical cycles
Languages : en
Pages : 100
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Book Description
A longstanding goal of organic biogeochemistry is to open the "black box" of microbial community metabolic capacity in order to understand how the vast complexity of organic chemical structures and microbial metabolisms give rise to observed patterns of organic matter reactivity. Microbial communities use diverse suites of extracellular enzymes to access complex organic compounds, which constitute the majority of bioavailable organic matter. Peptidase enzymes are responsible for degradation of protein, there are both endopeptidase and exopeptidase enzymes which cleave proteins from the end or the middle, respectively. Other than the exopeptidase enzyme Leucyl Aminopeptidase, constraints on peptidase activity are unknown. The purpose of this research is to determine what, if any, environmental variables control the production peptidase enzymes. Here we investigate the extent to which the freshness of organic matter and other water quality parameters control pathways of protein degradation as indicated by the ratio of exopeptidases to endopeptidases. Potential endo- and exopeptidase activities were measured in 32 freshwater samples from eastern TN and northeastern PA. We compared enzyme activities to organic matter concentrations and character, cell abundance, nutrient concentrations, and environmental parameters. There is evidence indicating that the ratio of endo- to exopeptidase activities are influenced by dissolved organic carbon (DOC) concentration and freshness. There is a similar relationship between endopeptidase to exopeptidase activity and cell densities, despite there being no correlation between DOC concentration and cell density. Fluorescent dissolved organic matter (FDOM) data indicates that terrestrial DOC dominates systems when DOC > 275 [mu]mol [micromoles] L−1 (per liter) whereas DOC
Author: Susan Elizabeth Jones
Publisher:
ISBN:
Category :
Languages : en
Pages : 330
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Book Description
Author: K. Ramesh Reddy
Publisher: CRC Press
ISBN: 0429531931
Category : Science
Languages : en
Pages : 926
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Book Description
The globally important nature of wetland ecosystems has led to their increased protection and restoration as well as their use in engineered systems. Underpinning the beneficial functions of wetlands are a unique suite of physical, chemical, and biological processes that regulate elemental cycling in soils and the water column. This book provides an in-depth coverage of these wetland biogeochemical processes related to the cycling of macroelements including carbon, nitrogen, phosphorus, and sulfur, secondary and trace elements, and toxic organic compounds. In this synthesis, the authors combine more than 100 years of experience studying wetlands and biogeochemistry to look inside the black box of elemental transformations in wetland ecosystems. This new edition is updated throughout to include more topics and provide an integrated view of the coupled nature of biogeochemical cycles in wetland systems. The influence of the elemental cycles is discussed at a range of scales in the context of environmental change including climate, sea level rise, and water quality. Frequent examples of key methods and major case studies are also included to help the reader extend the basic theories for application in their own system. Some of the major topics discussed are: Flooded soil and sediment characteristics Aerobic-anaerobic interfaces Redox chemistry in flooded soil and sediment systems Anaerobic microbial metabolism Plant adaptations to reducing conditions Regulators of organic matter decomposition and accretion Major nutrient sources and sinks Greenhouse gas production and emission Elemental flux processes Remediation of contaminated soils and sediments Coupled C-N-P-S processes Consequences of environmental change in wetlands# The book provides the foundation for a basic understanding of key biogeochemical processes and its applications to solve real world problems. It is detailed, but also assists the reader with box inserts, artfully designed diagrams, and summary tables all supported by numerous current references. This book is an excellent resource for senior undergraduates and graduate students studying ecosystem biogeochemistry with a focus in wetlands and aquatic systems.
Author: Jack J. Middelburg
Publisher: Springer
ISBN: 3030108228
Category : Science
Languages : en
Pages : 118
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Book Description
This open access book discusses biogeochemical processes relevant to carbon and aims to provide readers, graduate students and researchers, with insight into the functioning of marine ecosystems. A carbon centric approach has been adopted, but other elements are included where relevant or needed. The book focuses on concepts and quantitative understanding of primary production, organic matter mineralization and sediment biogeochemistry. The impact of biogeochemical processes on inorganic carbon dynamics and organic matter transformation are also discussed.
Author: Johannes Lehmann
Publisher: Routledge
ISBN: 1136571205
Category : Business & Economics
Languages : en
Pages : 450
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Book Description
Biochar is the carbon-rich product when biomass (such as wood, manure or crop residues) is heated in a closed container with little or no available air. It can be used to improve agriculture and the environment in several ways, and its stability in soil and superior nutrient-retention properties make it an ideal soil amendment to increase crop yields. In addition to this, biochar sequestration, in combination with sustainable biomass production, can be carbon-negative and therefore used to actively remove carbon dioxide from the atmosphere, with major implications for mitigation of climate change. Biochar production can also be combined with bioenergy production through the use of the gases that are given off in the pyrolysis process. This book is the first to synthesize the expanding research literature on this topic. The book's interdisciplinary approach, which covers engineering, environmental sciences, agricultural sciences, economics and policy, is a vital tool at this stage of biochar technology development. This comprehensive overview of current knowledge will be of interest to advanced students, researchers and professionals in a wide range of disciplines.
Author:
Publisher:
ISBN:
Category : Polycyclic aromatic hydrocarbons
Languages : en
Pages : 500
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Book Description
Author: Thomas S. Bianchi
Publisher: Princeton University Press
ISBN: 1400839106
Category : Science
Languages : en
Pages : 417
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Book Description
This textbook provides a unique and thorough look at the application of chemical biomarkers to aquatic ecosystems. Defining a chemical biomarker as a compound that can be linked to particular sources of organic matter identified in the sediment record, the book indicates that the application of these biomarkers for an understanding of aquatic ecosystems consists of a biogeochemical approach that has been quite successful but underused. This book offers a wide-ranging guide to the broad diversity of these chemical biomarkers, is the first to be structured around the compounds themselves, and examines them in a connected and comprehensive way. This timely book is appropriate for advanced undergraduate and graduate students seeking training in this area; researchers in biochemistry, organic geochemistry, and biogeochemistry; researchers working on aspects of organic cycling in aquatic ecosystems; and paleoceanographers, petroleum geologists, and ecologists. Provides a guide to the broad diversity of chemical biomarkers in aquatic environments The first textbook to be structured around the compounds themselves Describes the structure, biochemical synthesis, analysis, and reactivity of each class of biomarkers Offers a selection of relevant applications to aquatic systems, including lakes, rivers, estuaries, oceans, and paleoenvironments Demonstrates the utility of using organic molecules as tracers of processes occurring in aquatic ecosystems, both modern and ancient
