Biodegradation of radiolabeled cellulose acetate and cellulose propionate

Abstract

SYNOPSISBiodegradation of cellulose acetate and cellulose propionate was conclusively established with a naturally derived mixed microbial culture derived from activated sludge and 14C labeled cellulose esters. Radiolabeled cellulose esters were synthesized with either [ 1-14C] -acetate or [1-14C] -propionate and back hydrolyzed to the desired degree of substitution (DS) ranging from 1.77 to 2.64. Biodegradation was measured in an in uitro aerobic culture system that was designed to capture 14C02 produced by the aerobic microbial metabolism of the cellulose esters. Microorganisms were able to extensively degrade cellulose [ 1-14C] -acetate (CA) with DS ranging from 1.85 to 2.57 over periods of 14-31 days. More than 80% of the original 14C-polymeric carbon was biodegraded to 14C02 for CA substrates with a DS of 1.85. CA polymers with a DS of 2.07 and 2.57 yielded over 60% conversion to 14C02.The amount of biodegradation that was observed with cellulose [l-14C] -propionate with DS of 2.11, 2.44, and 2.64 were lower than the corresponding acetyl ester and ranged from 0.09 to 1.1%. However, cellulose [l-14C] -propionate with a DS of 1.77 and 1.84 underwent very rapid degradation in the mixed culture system, with 70 to over 80% conversion of labeled polymeric carbon metabolized to 14C02 in 29 days. The high level of microbial utilization of carbon from both cellulose esters and its conversion to C02 confirms the biodegradability of these polymers and the potential they have for total mineralization in natural microbiologically active environments.

Biofibres, biodegradable polymers and biocomposites: An overview

“…Gardner et al 156) showed, basing on film disintegration and on weight loss, that cellulose acetates, having DS less than approximately 2.20, compost at 53 8C and 60% moisture at rates comparable to that of PHBV. Komarek et al 155) provided via aerobic biodegradation of radiolabeled CA, that in CA with a DS of 1.85 more than 80% of the original 14 C-polymeric carbon was biodegraded to 14 CO 2 . The studies on biodegradation of CA although have been given much attention in recent times; scarce attention has been paid to the biodegradation of formulated resins consisting of cellulose acetate and diluents.…”

“…Cellulose esters, e. g., cellulose acetate (CA) are considered as potentially useful polymers in biodegradable applications [154][155][156][157][158][159][160] . CA is a modified polysaccharide synthesized by the reaction of acetic anhydride with cotton linters or wood pulp.…”

Degradation of Cellulose Acetate-Based Materials: A Review

“…One of the more convincing degradation studies was the aerobic biodegradation of radiolabelled CA by Komarek, Gardner, and Buchanan where they monitored the evolution of CO 2 from in vitro samples with the acetyl carbons labeled with 14 C [5]. The study compared CA with degrees of substitutions of 1.85, 2.07 and 2.57, and found the biodegradation rates were reduced, but not inhibited, by the higher levels of acetyl (Fig.…”

“…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.…”

In vitro enzymic synthesis of polymers containing saccharides, lignins, proteins or related compounds: a review

“…The available test methods have also been further extended to include biodegradation tests of packaging materials and plastics and other consumer products in accelerated land-Ðll, short-term controlled composting (up to 45 days) and longer-term composting (up to 6 months).47 A very precise method has been developed by Komarek et al for the establishment of the biodegradability of cellulose esters. 48 In this work radiolabelled cellulose acetate and propionate were tested with a mixed microbial culture derived from activated sludge. The extent of biodegradation was highly dependent on the degree of substitution of the polymers, and this was proven conclusively by the detection of liberated 14CO 2 indicating the microbial species had utilized the polymer as a carbon source.…”