Biodegradation of poly(vinyl alcohol) based materials

Anionic polyacrylamide (PAM) has been sold since 1995 to reduce irrigation‐induced erosion and enhance infiltration. Its soil stabilizing and flocculating properties improve runoff water quality by reducing sediments, N, dissolved reactive phosphorus (DRP) and total P, chemical oxygen demand (COD), pesticides, weed seeds, and microorganisms in runoff. PAM used for erosion control is a large (12–15 Mg mol −1 ) water‐soluble (non‐cross‐linked) anionic molecule, containing by PAM or can be slightly reduced. Typical seasonal application totals in furrow irrigation vary from 3 to 7 kg ha −1 . Research has shown little or no consistent adverse effect on soil microbial populations. Some evidence exists for PAM‐related yield increases where infiltration was crop‐limiting, especially in field portions having irregular slopes, where erosion prevention eliminated deep furrow cutting that deprives shallow roots of adequate water delivery. Modified water management with PAM shows great promise for water conservation. High effectiveness and low cost of PAM for erosion control and infiltration management, coupled with easier implementation than traditional conservation measures, has resulted in rapid adoption. About 800,000 ha of US irrigated land use PAM for erosion and/or infiltration management. In recent years, PAM has been deployed for uses beyond agricultural erosion control, including construction site erosion control, use in storm water runoff ponds to accelerate water clarification, soil stabilization and dust prevention in helicopter‐landing zones, and various other high‐traffic military situations. Among the newest topics being researched is the use of PAM to reduce ditch, canal, and pond seepage, using specific application protocols that take advantage of its increase of water viscosity at higher concentrations.

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Polyacrylamide in agriculture and environmental land management

Microbial degradation of poly(amino acid)s.

The interest in environmental issues is still growing and there are increasing demands to develop materials which do not burden the environment significantly. Awareness of the waste problem and its impact on the environment has awakened new interest in the area of degradable polymers. Biodegradation is necessary for water-soluble or water-miscible polymers because they eventually enter streams which can neither be recycled nor incinerated. It is important to consider the microbial degradation of natural and synthetic polymers in order to understand what is necessary for biodegradation and the mechanisms involved. This requires both biochemical insight and understanding of the interactions between materials and microorganisms. It is now widely requested that polymeric materials come from renewable resources instead of petrochemical sources. The microbial production of polymeric and oligomeric materials is also described.

Breakdown of plastics and polymers by microorganisms

Various types of poly(aspartic acid)s, which were poly(α-l-aspartic acid), poly(α-d-aspartic acid), poly(β-l-aspartic acid), and poly(α,β-d,l-aspartic acid)s, were prepared, and their biodegradabilities using the OECD 301C method and calcium ion chelating abilities were measured to clarify the relationship between the structure of poly(aspartic acid)s and these properties. Distinct tendencies were found both between the number of amide protons and biodegradability and between the ratio of the dicarboxylic acid end groups to the dicarboxylic acid end group plus succinimide end group and biodegradability. The chirality of the aspartic acid unit and the type of amide linkage in poly(aspartic acid) had no apparent effect on the biodegradability of poly(aspartic acid). The result of repetitive biodegradability analyses for poly-aspartic acid suggested the complete biodegradation is possible. Regarding the calcium ion chelating ability, only the type of amide linkage affected the calcium ion chelating ability. ...

Relationships between Structure and Properties of Poly(aspartic acid)s

Arthrobacter sp. strain NO-18 was first isolated from soil as a bacterium which could degrade the sodium acrylate oligomer and utilize it as the sole source of carbon. When 0.2% (wt/wt) oligomer was added to the culture medium, the acrylate oligomer was found to be degraded by 70 to 80% in 2 weeks, using gel permeation chromatography. To determine the maximum molecular weight for biodegradation, the degradation test was done with the hexamer, heptamer, and octamer, which were separated from the oligomer mixture by fractional gel permeation chromatography. The hexamer and heptamer were consumed to the extents of 58 and 36%, respectively, in 2 weeks, but the octamer was not degraded. Oligomers with three different terminal groups were synthesized to examine the effect of the different terminal groups on biodegradation, but few differences were found. Arthrobacter sp. NO-18 assimilated acrylic acid, propionic acid, glutaric acid, 2-methylglutaric acid, and 1,3,5-pentanetricarboxylic acid. Degradation of the acrylic unit structure by this strain is discussed.

Degradation of a Sodium Acrylate Oligomer by an Arthrobacter sp

Arthrobacter sp.strain NO-18was first isolated fromsoil as a bacterium whichcoulddegrade thesodium acrylate oligomer andutilize itasthesole sourceofcarbon. When0.2%(wt/wt) oligomer was addedtothe culture medium, theacrylate oligomer was found tobedegraded by70to80%oin2weeks, using gelpermeation chromatography. Todetermine themaximummolecular weight forbiodegradation, thedegradation test was donewiththehexamer, heptamer, andoctamer, which were separated fromtheoligomer mixture byfractional gelpermeation chromatography. Thehexamer andheptamer were consumed totheextents of58and36%, respectively, in2weeks, buttheoctamerwas notdegraded. Oligomers withthreedifferent terminal groups were synthesized toexamine theeffect ofthedifferent terminal groups on biodegradation, butfewdifferences were found. Arthrobacter sp.NO-18assimilated acrylic acid, propionic acid, glutaric acid, 2-methylglutaric acid, and1,3,5-pentanetricarboxylic Degradation oftheacrylic unit structure bythis strain isdiscussed. Poly(sodium acrylate) isa water-soluble andharmless synthetic polymer widely usedas a functional polymer in various fields. Although microbial degradation ofsynthetic polymers hasattracted muchinterest asa means ofmildand effective wastetreatment, little information isavailable on biodegradation ofpoly(sodium acrylate), whichisconsid- eredhighly resistant tomicrobial degradation.

Masaharu Mukouyama

Papers

Degradation of a Sodium Acrylate Oligomer by an Arthrobacter sp

Degradation ofa SodiumAcrylate Oligomer byan Arthrobacter sp.