One of the major environmental problems today is hydrocarbon contamination resulting from the activities related to the petrochemical industry. Accidental releases of petroleum products are of particular concern in the environment. Hydrocarbon components have been known to belong to the family of carcinogens and neurotoxic organic pollutants. Currently accepted disposal methods of incineration or burial insecure landfills can become prohibitively expensive when amounts of contaminants are large. Mechanical and chemical methods generally used to remove hydrocarbons from contaminated sites have limited effectiveness and can be expensive. Bioremediation is the promising technology for the treatment of these contaminated sites since it is cost-effective and will lead to complete mineralization. Bioremediation functions basically on biodegradation, which may refer to complete mineralization of organic contaminants into carbon dioxide, water, inorganic compounds, and cell protein or transformation of complex organic contaminants to other simpler organic compounds by biological agents like microorganisms. Many indigenous microorganisms in water and soil are capable of degrading hydrocarbon contaminants. This paper presents an updated overview of petroleum hydrocarbon degradation by microorganisms under different ecosystems.

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Microbial Degradation of Petroleum Hydrocarbon Contaminants: An Overview

Outlook for cellulase improvement: screening and selection strategies.

The microbiota of the mammalian intestine depend largely on dietary polysaccharides as energy sources. Most of these polymers are not degradable by the host, but herbivores can derive 70% of their energy intake from microbial breakdown — a classic example of mutualism. Moreover, dietary polysaccharides that reach the human large intestine have a major impact on gut microbial ecology and health. Insight into the molecular mechanisms by which different gut bacteria use polysaccharides is, therefore, of fundamental importance. Genomic analyses of the gut microbiota could revolutionize our understanding of these mechanisms and provide new biotechnological tools for the conversion of polysaccharides, including lignocellulosic biomass, into monosaccharides.

Polysaccharide utilization by gut bacteria: potential for new insights from genomic analysis

Immobilization of biomolecules onto surfaces is important in many of the biological and physical sciences, including cell and molecular biology, analytical chemistry, and in applied and interdisciplinary fields such as medical diagnostics, tissue engineering, and bioprocess engineering.[1-4] Strategies for biomolecule immobilization onto surfaces generally exploit either noncovalent or covalent reactions. Noncovalent methods allow reversible immobilization of biomolecules under specific conditions, and include physical adsorption and affinity immobilization. Some widely adapted examples are (strep)avidin-biotin, nitriloacetic acid (NTA)-histidine, and DNA-DNA interactions.[5-8] In contrast, covalent immobilization of molecules onto surfaces typically relies on conjugation reactions between ‘active’ functional groups, such as N-hydroxysuccinimide (NHS)[9] or maleimide,[10] and companion target moieties, such as amines and sulfhydryls. For reactions involving biomolecules performed in aqueous solvents, susceptibility of NHS, maleimide, and other activating groups to hydrolysis during storage and reaction can lead to low efficiency of surface bioconjugation.[11,12] In this study, we report a facile two-step aqueous approach to immobilization of biomolecules onto surfaces. The approach involves simple dip-coating of a biomimetic polymer thin film onto a substrate, followed by conjugation of biomolecules to the biomimetic polymer film. The method exploits the latent reactivity of the biomimetic polymer thin film towards nucleophiles, is unaffected by water, and allows for discrimination between nucleophiles on the basis of pKa.

Facile Conjugation of Biomolecules onto Surfaces via Mussel Adhesive Protein Inspired Coatings

Cloning and characterization of the

https://www2.biology.uoc.gr/courses/BIO113_Enzimiki_biotexnologia/images/documents/1.pdf

Enzyme technology: an overview

Expanding the alkane oxygenase toolbox: new enzymes and applications.

Oxidative biotransformations using oxygenases.

Selection experiments and protein engineering were used to identify an amino acid position in integral membrane alkane hydroxylases (AHs) that determines whether long-chain-length alkanes can be hydroxylated by these enzymes. First, substrate range mutants of the Pseudomonas putida GPo1 and Alcanivorax borkumensis AP1 medium-chain-length AHs were obtained by selection experiments with a specially constructed host. In all mutants able to oxidize alkanes longer than C13, W55 (in the case of P. putida AlkB) or W58 (in the case of A. borkumensis AlkB1) had changed to a much less bulky amino acid, usually serine or cysteine. The corresponding position in AHs from other bacteria that oxidize alkanes longer than C13 is occupied by a less bulky hydrophobic residue (A, V, L, or I). Site-directed mutagenesis of this position in the Mycobacterium tuberculosis H37Rv AH, which oxidizes C10 to C16 alkanes, to introduce more bulky amino acids changed the substrate range in the opposite direction; L69F and L69W mutants oxidized only C10 and C11 alkanes. Subsequent selection for growth on longer alkanes restored the leucine codon. A structure model of AHs based on these results is discussed.

Identification of an Amino Acid Position That Determines the Substrate Range of Integral Membrane Alkane Hydroxylases

Stereoselective Desymmetrizations by Recombinant Whole Cells Expressing the Baeyer–Villiger Monooxygenase from Xanthobacter sp. ZL5: A New Biocatalyst Accepting Structurally Demanding Substrates

Jan B. van Beilen

Papers

Enzyme technology: an overview

Expanding the alkane oxygenase toolbox: new enzymes and applications.

Oxidative biotransformations using oxygenases.

Identification of an Amino Acid Position That Determines the Substrate Range of Integral Membrane Alkane Hydroxylases

Stereoselective Desymmetrizations by Recombinant Whole Cells Expressing the Baeyer–Villiger Monooxygenase from Xanthobacter sp. ZL5: A New Biocatalyst Accepting Structurally Demanding Substrates