Molecular weight distribution of hydrolysis products during the biodegradation of model macromolecules in suspended and biofilm cultures. II. Dextran and dextrin

David R. Confer, Bruce Ernest Logan

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

To improve wastewater treatment models, it is important to consider that wastewater is composed of a variety of complex molecules, many molecules having large molecular weights. Previous experiments have shown that hydrolytic enzymes are cell-associated and that hydrolytic fragments accumulate in bulk solution during the degradation of a model polysaccharide (dextran) in pure culture. These results indicate that incompletely hydrolyzed macromolecules are released into solution prior to their complete degradation. The authors wanted to determine whether the release of incompletely degraded molecules was specific to dextran degradation by pure cultures or whether it could be generalized to mixed culture systems and the degradation of other polysaccharides. To accomplish this, both pure and mixed (wastewater) cultures were used to examine the degradation of dextran and another macromolecular polysaccharide, dextrin, in batch suspended culture, continuous suspended culture and fixed-film reactor systems. Membrane ultrafiltration was used to monitor the molecular weight distribution of polysaccharides in solution during degradation. In all reactor configurations, and for all substrates and inocula investigated, small-molecular-weight ( < 1000 amu) oligosaccharides accumulated in solution during polysaccharide degradation. These results, in conjunction with results of enzyme studies, support a generalized model for macromolecular degradation by cells that features cell-bound hydrolysis of polysaccharides and the subsequent release of hydrolytic fragments back into bulk solution. This hydrolysis and release is repeated until fragments are small enough ( < 1000 amu) to be assimilated by cells. Essential features of this model are that polysaccharide diffusivity changes during its degradation and that different enzymes, with different methods of operation and different kinetic characteristics, may be used in successive hydrolytic cleavages. These features are particularly important to consider in evaluating macromolecule degradation by aggregates and biofilms and in understanding; overall uptake kinetics in bioreactors.

Original languageEnglish (US)
Pages (from-to)2137-2145
Number of pages9
JournalWater Research
Volume31
Issue number9
DOIs
StatePublished - Sep 1 1997

Fingerprint

Dextran
Biofilms
Molecular weight distribution
Biodegradation
Macromolecules
biofilm
hydrolysis
Hydrolysis
biodegradation
Polysaccharides
polysaccharide
Degradation
degradation
suspended culture
Enzymes
enzyme
Molecules
Wastewater
Molecular weight
distribution

All Science Journal Classification (ASJC) codes

  • Ecological Modeling
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution

Cite this

@article{c595eb6291af4c46baaffd185f093127,
title = "Molecular weight distribution of hydrolysis products during the biodegradation of model macromolecules in suspended and biofilm cultures. II. Dextran and dextrin",
abstract = "To improve wastewater treatment models, it is important to consider that wastewater is composed of a variety of complex molecules, many molecules having large molecular weights. Previous experiments have shown that hydrolytic enzymes are cell-associated and that hydrolytic fragments accumulate in bulk solution during the degradation of a model polysaccharide (dextran) in pure culture. These results indicate that incompletely hydrolyzed macromolecules are released into solution prior to their complete degradation. The authors wanted to determine whether the release of incompletely degraded molecules was specific to dextran degradation by pure cultures or whether it could be generalized to mixed culture systems and the degradation of other polysaccharides. To accomplish this, both pure and mixed (wastewater) cultures were used to examine the degradation of dextran and another macromolecular polysaccharide, dextrin, in batch suspended culture, continuous suspended culture and fixed-film reactor systems. Membrane ultrafiltration was used to monitor the molecular weight distribution of polysaccharides in solution during degradation. In all reactor configurations, and for all substrates and inocula investigated, small-molecular-weight ( < 1000 amu) oligosaccharides accumulated in solution during polysaccharide degradation. These results, in conjunction with results of enzyme studies, support a generalized model for macromolecular degradation by cells that features cell-bound hydrolysis of polysaccharides and the subsequent release of hydrolytic fragments back into bulk solution. This hydrolysis and release is repeated until fragments are small enough ( < 1000 amu) to be assimilated by cells. Essential features of this model are that polysaccharide diffusivity changes during its degradation and that different enzymes, with different methods of operation and different kinetic characteristics, may be used in successive hydrolytic cleavages. These features are particularly important to consider in evaluating macromolecule degradation by aggregates and biofilms and in understanding; overall uptake kinetics in bioreactors.",
author = "Confer, {David R.} and Logan, {Bruce Ernest}",
year = "1997",
month = "9",
day = "1",
doi = "10.1016/S0043-1354(97)00050-X",
language = "English (US)",
volume = "31",
pages = "2137--2145",
journal = "Water Research",
issn = "0043-1354",
publisher = "Elsevier Limited",
number = "9",

}

TY - JOUR

T1 - Molecular weight distribution of hydrolysis products during the biodegradation of model macromolecules in suspended and biofilm cultures. II. Dextran and dextrin

AU - Confer, David R.

AU - Logan, Bruce Ernest

PY - 1997/9/1

Y1 - 1997/9/1

N2 - To improve wastewater treatment models, it is important to consider that wastewater is composed of a variety of complex molecules, many molecules having large molecular weights. Previous experiments have shown that hydrolytic enzymes are cell-associated and that hydrolytic fragments accumulate in bulk solution during the degradation of a model polysaccharide (dextran) in pure culture. These results indicate that incompletely hydrolyzed macromolecules are released into solution prior to their complete degradation. The authors wanted to determine whether the release of incompletely degraded molecules was specific to dextran degradation by pure cultures or whether it could be generalized to mixed culture systems and the degradation of other polysaccharides. To accomplish this, both pure and mixed (wastewater) cultures were used to examine the degradation of dextran and another macromolecular polysaccharide, dextrin, in batch suspended culture, continuous suspended culture and fixed-film reactor systems. Membrane ultrafiltration was used to monitor the molecular weight distribution of polysaccharides in solution during degradation. In all reactor configurations, and for all substrates and inocula investigated, small-molecular-weight ( < 1000 amu) oligosaccharides accumulated in solution during polysaccharide degradation. These results, in conjunction with results of enzyme studies, support a generalized model for macromolecular degradation by cells that features cell-bound hydrolysis of polysaccharides and the subsequent release of hydrolytic fragments back into bulk solution. This hydrolysis and release is repeated until fragments are small enough ( < 1000 amu) to be assimilated by cells. Essential features of this model are that polysaccharide diffusivity changes during its degradation and that different enzymes, with different methods of operation and different kinetic characteristics, may be used in successive hydrolytic cleavages. These features are particularly important to consider in evaluating macromolecule degradation by aggregates and biofilms and in understanding; overall uptake kinetics in bioreactors.

AB - To improve wastewater treatment models, it is important to consider that wastewater is composed of a variety of complex molecules, many molecules having large molecular weights. Previous experiments have shown that hydrolytic enzymes are cell-associated and that hydrolytic fragments accumulate in bulk solution during the degradation of a model polysaccharide (dextran) in pure culture. These results indicate that incompletely hydrolyzed macromolecules are released into solution prior to their complete degradation. The authors wanted to determine whether the release of incompletely degraded molecules was specific to dextran degradation by pure cultures or whether it could be generalized to mixed culture systems and the degradation of other polysaccharides. To accomplish this, both pure and mixed (wastewater) cultures were used to examine the degradation of dextran and another macromolecular polysaccharide, dextrin, in batch suspended culture, continuous suspended culture and fixed-film reactor systems. Membrane ultrafiltration was used to monitor the molecular weight distribution of polysaccharides in solution during degradation. In all reactor configurations, and for all substrates and inocula investigated, small-molecular-weight ( < 1000 amu) oligosaccharides accumulated in solution during polysaccharide degradation. These results, in conjunction with results of enzyme studies, support a generalized model for macromolecular degradation by cells that features cell-bound hydrolysis of polysaccharides and the subsequent release of hydrolytic fragments back into bulk solution. This hydrolysis and release is repeated until fragments are small enough ( < 1000 amu) to be assimilated by cells. Essential features of this model are that polysaccharide diffusivity changes during its degradation and that different enzymes, with different methods of operation and different kinetic characteristics, may be used in successive hydrolytic cleavages. These features are particularly important to consider in evaluating macromolecule degradation by aggregates and biofilms and in understanding; overall uptake kinetics in bioreactors.

UR - http://www.scopus.com/inward/record.url?scp=0031239028&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0031239028&partnerID=8YFLogxK

U2 - 10.1016/S0043-1354(97)00050-X

DO - 10.1016/S0043-1354(97)00050-X

M3 - Article

AN - SCOPUS:0031239028

VL - 31

SP - 2137

EP - 2145

JO - Water Research

JF - Water Research

SN - 0043-1354

IS - 9

ER -