Effects of natural polymer acetylation on the anaerobic bioconversion to methane and carbon dioxide

Abstract

The successful production of novel biodegradable plastic copolymers incorporating both synthetic plastic formulations, such as polystyrene, and naturally occurring biodegradable polymer components, such as cellulose, starch, or xylan, requires stable chemical bonding between these polymers. Modification of the natural polymers through acetylation of the available hydroxyl groups permits the formation of appropriate film-forming plastic copolymers. However, modification of natural polymers has been demonstrated to result in decreased attack by microbial catalysts. For this study, the abundant natural polymers cellulose, starch, and xylan were substituted with acetate to various degrees, and the effect of this modification on the anaerobic biodegradation was assessed using the biochemical methane potential (BMP) protocol. Significant reduction in anaerobic biodegradability resulted with all polymers at substitution levels of between 1.2-1.7. For the xylan acetate series, the trends for anaerobic biodegradation were in good agreement with reduced enzymatic hydyolysis using commercially available xylanase preparations.

Degradation of Cellulose Acetate-Based Materials: A Review

“…Rivard et al in 1992 [7] studied CA of increasing DS (0.82-2.4) by incubating them with a special culture for a period of 98 days, and found that CA of DS \1.25 were significantly degraded. The samples with DS [1.7 were also degraded, but to a lesser extent.…”

“…Later the importance of the deacetylation step was shown, when it was learned that acetyl esterase enzymes are common in microorganisms. Currently CA is generally recognized as a biodegradable polymer within the scientific community [4][5][6][7][8]. Recent work has allowed a considerable increase in the knowledge of the enzymology of non-substituted and acetylated polysaccharides, thus illuminating the biodegradation mechanism.…”

Carbohydrate derived‐pseudo‐lignin can retard cellulose biological conversion

“…However, surprisingly, the 4 and 120 h enzymatic digestibilities of Table II. However, it can be hypothesized that possible cellulose acetylation due to presence of acetyl groups and methylation from 4-Dmethyl glucuronic acid on the xylan backbone during pretreatment and/or residual xylan (<2 wt%) could result in less reactive cellulose, as it is well known that cellulose methylation and acetylation retards cellulase activity (Rivard et al, 1992). solids resulting from pretreatment of cellulose mixed with xylan or xylose were still considerably lower than digestion of cellulose that was pretreated alone at the same severities (Table II).…”

“…Although the 6-7 wt% ash content makes it a significant constituent in commercial beechwood xylan, so little is left following pretreatment (data not shown) that it would be highly unlikely to impact hydrolysis. However, it can be hypothesized that possible cellulose acetylation due to presence of acetyl groups and methylation from 4-Dmethyl glucuronic acid on the xylan backbone during pretreatment and/or residual xylan (<2 wt%) could result in less reactive cellulose, as it is well known that cellulose methylation and acetylation retards cellulase activity (Rivard et al, 1992). Causes for cellulose reduced digestibility at low severity: cellulose acetylation.…”

Purification and Characterization of an Endo-1,4-β-glucanase fromNeisseria siccaSB that Hydrolyzes β-1,4 Linkages in Cellulose Acetate

“…Reese 2) has reported that several cellulolytic microorganisms such as Pestalotiopsis westerdijkii QM 381 produced cellobiose octaacetatease, which deacetylated cellobiose octaacetate and water-soluble CA (DS, 0.76). It has been reported that CA membranes (DS, 2.5 and 2.8) were degraded by some microorganisms 3) and CAˆl ms (DS, 1.7 and 2.5) were degraded by Pseudomonas paucimobilis 4) , activated sludge, [5][6][7][8] and Bacillus sp. S2055.…”