Biodegradation of diisodecyl phthalate (DIDP) by Bacillus sp. SB‐007

Abstract

In this study, diisodecyl phthalate (DIDP) was efficiently degraded by Bacillus sp. SB-007. The optimal conditions for DIDP (100 mg l(-1)) degradation by Bacillus sp. SB-007 in a mineral salts medium were found to be pH 7.0 at 30 degrees C, stirring at 200 rpm. The specific rate of DIDP degradation was found to be concentration dependent with a maximum of 4.87 mg DIDP l(-1) h(-1). DIDP was transformed rapidly by Bacillus sp. SB-007 with the formation of monoisodecyl phthalate and phthalic acid, which subsequently degraded further. These results highlight the potential of this bacterium for removing DIDP contaminated waste in the environment.

Plasticizer Degradation by Marine Bacterial Isolates: A Proteogenomic and Metabolomic Characterization

“…While butyl benzoate may come as a consequence of monobutyl phthalate decarboxylation (and it is unknown whether it is then further processed into benzoate as this intermediate was not detected), phthalic anhydride may function as a detoxification strategy during the build-up of phthalate. Phthalic anhydride was previously detected during the degradation of the long-chain PAEs DINP and DIDP, , as well as dipentyl phthalate . A dihydroxy acid dehydratase (3668) that could be responsible for catalyzing this reaction was slightly upregulated in both the presence of phthalate and DBP (i.e., 1.9-fold; Supporting Information Table S5); however, it is also possible that this could occur through a hydrolysis reaction for which a number of enzymes could be responsible or spontaneous decay of phthaloyl-CoA as suggested during anaerobic biodegradation of phthalate. , The hydrolyzed DBP side chains, that is, two butanol molecules, are further metabolized through the action of alcohol and aldehyde dehydrogenases (3195 and 5697, respectively) and a fatty acid-CoA ligase (1663) before entering the short-chain fatty acid β-oxidation pathway (4429–4434), a pathway previously suggested, and for which all enzymes were strongly upregulated in this treatment (Figure ).…”

“…41,73,74 Here, we show that phthalate is toxic to both organisms, even when an additional carbon source is present (Supporting Information Figure S4), but that there are a number of adaptations adopted by the two isolates to deal with phthalate toxicity, for example, via conversion into phthalic anhydride, as observed by metabolomics, or the production of stress response mechanisms and efflux pumps, as shown by proteomics. While phthalic anhydride was previously reported in other PAE biodegradation studies 29,30,61 and is known to be less toxic than phthalic acid, 75 the mechanisms or reasons for its production were not discussed in these studies. While it is possible that the dehydration of phthalate could occur spontaneously at high temperatures, many previous PAE degradation studies have not reported phthalic anhydride production.…”

“…Phthalate and its isomers are known toxic compounds. ,, Here, we show that phthalate is toxic to both organisms, even when an additional carbon source is present (Supporting Information Figure S4), but that there are a number of adaptations adopted by the two isolates to deal with phthalate toxicity, for example, via conversion into phthalic anhydride, as observed by metabolomics, or the production of stress response mechanisms and efflux pumps, as shown by proteomics. While phthalic anhydride was previously reported in other PAE biodegradation studies ,, and is known to be less toxic than phthalic acid, the mechanisms or reasons for its production were not discussed in these studies. While it is possible that the dehydration of phthalate could occur spontaneously at high temperatures, many previous PAE degradation studies have not reported phthalic anhydride production. ,− Carboxylic acid anhydride production usually requires the presence of a catalyst or an enzyme under the physiological conditions used here and, while we suggest a dihydroxy acid dehydratase as being responsible for phthalic anhydride production, this compound could also be produced by phthaloyl-CoA decay during the anaerobic degradation of phthalate, , although the enzyme responsible for the production of phthaloyl-CoA (i.e., succinyl-CoA/phthalate-CoA transferase) was not found in either isolate (Supporting Information Tables S2, S5, and S6).…”

“…In fact, one study found that using ATBC as a plasticizer actually decreased enzymatic degradation rates of the biodegradable plastic poly­(lactic acid) . On the other hand, the pathways used for PAE biodegradation have been characterized to some extent in a number of terrestrial microorganisms. ,,− ,− Esterases have been suggested to carry out the first step of PAE biodegradation by hydrolyzing the side chains and generating phthalate and short-chain alcohols and fatty acids. ,,,,− However, only two of these studies , actually identified the specific esterases involved and, furthermore, β-oxidation of the side-chain fatty acids has even been suggested to occur directly on the PAE molecule. , Hence, it is not known whether the mechanism for biodegradation is the same for different PAE plasticizers. The metabolic pathways for phthalate degradation are well established and follow one of the branches of the β-ketoadipate pathway. ,, Despite the widespread distribution of plastics and, consequently, plasticizers in the oceans, the degradation of these additives by marine bacteria has been less extensively studied ,, and the catabolic pathways are unknown.…”