Biodegradation mechanisms

Hydrocarbon Microbiology biodegradation mechanisms of oil products (gasoline, kerosene, diesel, etc.), pyrolysis, polycyclic aromatic hydrocarbons, chlorinated solvents, and ether fuels refining processes (e.g., oil product microbial desulfurization) and oil production processes (e.g., bacterial corrosion). 

Marcomini et al. [42] studied the aerobic biodegradation mechanisms of different commercial AE blends (linear, oxo- and multibranched alkyl chains) by analysing the metabolites under the same standardised conditions applying liquid chromatography mass spectrometry LC-MS. 

The data suggest that in a saline medium the biodegradation of PEG continues and that the main biodegradation mechanism is... 

PVAc, PVA and PVB homopolymers as well as the different copolymers mentioned above all have a similar chemical motif in common. They exhibit an all carbon-carbon single bond backbone, which needs to be broken at some point in a potential biodegradation mechanism. With respect to the backbone, poly(vinyl ester)s are closely related to poly(olefin)s, poly(styrene)s and poly(acrylate)s. These three are known not to be biodegradable. Instead, they usually decompose by the impact of UV radiation, oxidation and hydrolysis reactions, which are not considered to be biological degradation. 

Lucas N, Bienaime C, Belloy C, Queneudec M, Silvestre F, Nava-Saucedo JE (2008) Polymer biodegradation mechanisms and estimation techniques. Chemosphere 73 429 142... 

Table I. Comparison of Lignin Biosynthesis and Biodegradation Mechanisms...

Marcomini, A., and M. Zanette. 1996. Biodegradation mechanisms of aliphatic alcohol polyethoxy-lates (AE) under standardized aerobic conditions (modified OECD screening test 301E). Riv. Ital. Sost. Grasse 73, 213-218. 

As a basic in B LMs for the wastewater treatment the author presents two-phase partitioning bioreactors. He presents the main criteria which must be considered in the selection of the LM solvent biocompatibility (toxicity of the solvent to the microorganism), bioavailabihty (resistance of the solvent to biodegradation by the microorganism used), immiscibility in the aqueous phase, high solubility of pollutant in the solvent, favorable mass-transfer characteristics, etc. Biodegradation mechanisms and kinetics are discussed. Apphcations of bioreactors in wastewater treatment in laboratory, phot, and industrial scale are reviewed. Potential applications are considered also. 

Organic carbon is accounted for by lactose, fats, and proteins [112-114]. To a hmited extent, protein and fat loading can be removed using precipitation [115]. Practical problems with precipitation arise from the low removal efficiencies, as well as from the need for expensive reagents [109]. Casein accounts for 80% of total protein in dairy wastewaters, and hydrolysis is the main biodegradation mechanism regardless of the concentration of oxygen, that is, whether anaerobic or aerobic treatment methods are used... 

Biodegradation of DMSD has been established by using C-labeled substrate. The biodegradative mechanism for DMSD involves initial oxidation of a methyl group (Equation (11)), with the formation of methylsilanetriol as intermediate, in a pathway leading to silica. ... 

Photo-biodegradable polyethylene using the above system was developed commercially for use in agriculture by D. Gilead of Plastopil Hazorea in Israel in collaboration with the author and is now widely used as Plastor in mulching films in Europe and Plastigone in the USA. It is also used in polypropylene baler twines as Cleanfields by AMBRACO in the USA, and in controlled release fertilisers as Nutri-cote by Chisso-Asahi Fertilizer Company in Japan. The biodegradation mechanism will be discussed below. 

Saucedo, J.-E. Polymer biodegradation Mechanisms and estimation techniques. 2008, 73, 429-442. 

Bulk characterization yields information on the macroscopic properties of the biomaterial such as thermal, mechanical, solubility, optical, and dielectric properties. Surface characterization yields morphological information that is critical for interfacing the implant or drug delivery device with the host tissue. This could be achieved by microscopic and spectfoscopic methods. Next in the hierarchy is the characterization of processes such as biodegradation mechanism and kinetics under biomimetic in vitro conditions. Cases of implanted device failure need to be assessed by systematic interrogation of explanted medical devices. After knowing the basic characteristics of the biomaterial, real-time investigation of in vivo processes plays a major role in the successful journey of an implant. 

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