Hybrid algal photosynthesis and ion exchange (HAPIX) process for high ammonium strength wastewater treatment.

A hybrid algal photosynthesis and ion exchange (HAPIX) process was developed that uses natural zeolite (chabazite) and wild type algae to treat high ammonium (NH) strength wastewater. In the HAPIX process, NH is temporarily adsorbed from the liquid, which reduces the free ammonia (FA) concentration below the inhibitory level for algal growth. The slow release of adsorbed NH subsequently supports the continuous growth of algae.

Bioregeneration of Chabazite During Nitrification of Centrate from Anaerobically Digested Livestock Waste: Experimental and Modeling Studies.

Nitrification of high total ammonia nitrogen-strength wastewaters is challenging due to free ammonia (FA) inhibition of nitrification. FA inhibition can potentially be alleviated by temporarily adsorbing ammonium (NH) to natural zeolite, such as chabazite, followed by direct zeolite bioregeneration via nitrification. In this research, the effectiveness of chabazite addition for reducing nitrification inhibition during treatment of centrate from anaerobic digestion of swine waste was quantified.

Oxidative Maturation and Structural Characterization of Prenylated FMN Binding by UbiD, a Decarboxylase Involved in Bacterial Ubiquinone Biosynthesis.

The activity of the reversible decarboxylase enzyme Fdc1 is dependent on prenylated FMN (prFMN), a recently discovered cofactor. The oxidized prFMN supports a 1,3-dipolar cycloaddition mechanism that underpins reversible decarboxylation. Fdc1 is a distinct member of the UbiD family of enzymes, with the canonical UbiD catalyzing the (de)carboxylation of -hydroxybenzoic acid-type substrates.

Epoxyqueuosine Reductase Structure Suggests a Mechanism for Cobalamin-dependent tRNA Modification.

Queuosine (Q) is a hypermodified RNA base that replaces guanine in the wobble positions of 5'-GUN-3' tRNA molecules. Q is exclusively made by bacteria, and the corresponding queuine base is a micronutrient salvaged by eukaryotic species. The final step in Q biosynthesis is the reduction of the epoxide precursor, epoxyqueuosine, to yield the Q cyclopentene ring.

New cofactor supports α,β-unsaturated acid decarboxylation via 1,3-dipolar cycloaddition.

The bacterial ubiD and ubiX or the homologous fungal fdc1 and pad1 genes have been implicated in the non-oxidative reversible decarboxylation of aromatic substrates, and play a pivotal role in bacterial ubiquinone (also known as coenzyme Q) biosynthesis or microbial biodegradation of aromatic compounds, respectively. Despite biochemical studies on individual gene products, the composition and cofactor requirement of the enzyme responsible for in vivo decarboxylase activity remained unclear. Here we show that Fdc1 is solely responsible for the reversible decarboxylase activity, and that it requires a new type of cofactor: a prenylated flavin synthesized by the associated UbiX/Pad1.

UbiX is a flavin prenyltransferase required for bacterial ubiquinone biosynthesis.

Ubiquinone (also known as coenzyme Q) is a ubiquitous lipid-soluble redox cofactor that is an essential component of electron transfer chains. Eleven genes have been implicated in bacterial ubiquinone biosynthesis, including ubiX and ubiD, which are responsible for decarboxylation of the 3-octaprenyl-4-hydroxybenzoate precursor. Despite structural and biochemical characterization of UbiX as a flavin mononucleotide (FMN)-binding protein, no decarboxylase activity has been detected.

Crystal structure of X-prolyl aminopeptidase from Caenorhabditis elegans: A cytosolic enzyme with a di-nuclear active site.

Eukaryotic aminopeptidase P1 (APP1), also known as X-prolyl aminopeptidase (XPNPEP1) in human tissues, is a cytosolic exopeptidase that preferentially removes amino acids from the N-terminus of peptides possessing a penultimate N-terminal proline residue. The enzyme has an important role in the catabolism of proline containing peptides since peptide bonds adjacent to the imino acid proline are resistant to cleavage by most peptidases. We show that recombinant and catalytically active Caenorhabditis elegans APP-1 is a dimer that uses dinuclear zinc at the active site and, for the first time, we provide structural information for a eukaryotic APP-1 in complex with the inhibitor, apstatin.

Reductive dehalogenase structure suggests a mechanism for B12-dependent dehalogenation.

Organohalide chemistry underpins many industrial and agricultural processes, and a large proportion of environmental pollutants are organohalides. Nevertheless, organohalide chemistry is not exclusively of anthropogenic origin, with natural abiotic and biological processes contributing to the global halide cycle. Reductive dehalogenases are responsible for biological dehalogenation in organohalide respiring bacteria, with substrates including polychlorinated biphenyls or dioxins.

Preservation of human tear protein structure and function by a novel contact lens multipurpose solution containing protein-stabilizing agents.

Objectives: Tear film proteins have antimicrobial and other functions that may be lost after denaturation during contact lens wear. A new multipurpose solution has recently become available (Biotrue, Bausch + Lomb Inc., Rochester, NY), which contains protein-stabilizing agents including hyaluronic acid, poloxamine, and sulfobetaine 10, the latter used previously as a laboratory tool to renature proteins.

Discovery of a putative acetoin dehydrogenase complex in the hyperthermophilic archaeon Sulfolobus solfataricus.

Like many other aerobic archaea, the hyperthermophile Sulfolobus solfataricus possesses a gene cluster encoding components of a putative 2-oxoacid dehydrogenase complex. In the current paper, we have cloned and expressed the first two genes of this cluster and demonstrate that the protein products form an alpha(2)beta(2) hetero-tetramer possessing the catalytic activity characteristic of the first component enzyme of an acetoin dehydrogenase multienzyme complex. This represents the first report of an acetoin multienzyme complex in archaea, and contrasts with the branched-chain 2-oxoacid dehydrogenase complex activities characterised in two other archaea, Thermoplasma acidophilum and Haloferax volcanii.

Role of finite populations in determining evolutionary dynamics.

The connection between the finite size of an evolving population and its dynamical behavior is examined through analytical and computational studies of a simple model of evolution. The infinite population limit of the model is shown to be governed by a special case of the quasispecies equations. A flat fitness landscape yields identical results for the dynamics of infinite and finite populations.