James S. Maki

Bio: James S. Maki is an academic researcher from Marquette University. The author has contributed to research in topics: Bioaugmentation & Methanogen. The author has an hindex of 21, co-authored 32 publications receiving 1525 citations.

Molecular approaches to nontoxic antifouling

Abstract: Summary A consequence of environmental and human health concerns arising from the use of toxic metals in marine antifouling coatings has been to recognise the need for a nontoxic alternative to fouling control. Recent research has focused on two approaches to this problem: the development of (a) foul-release coatings that work on the principle of either low surface free energy or coating ablation, and (b) coatings that incorporate a compound(s) that is nontoxic, or at least environmentally benign, that will deter fouling. Here we discuss the nature of the fouling problem and a new technology that is emerging to address it. The use of natural marine products and of analogues to these compounds holds considerable promise and is an area of intense research. It is recognized, however, that a melding of the technologies of foul-release and foul-deterrence may be required to develop broad spectrum, nontoxic antifouling coatings. This approach may more closely reflect antifouling strategies adopted by marine org...

Relating Anaerobic Digestion Microbial Community and Process Function

Abstract: Anaerobic digestion (AD) involves a consortium of microorganisms that convert substrates into biogas containing methane for renewable energy. The technology has suffered from the perception of being periodically unstable due to limited understanding of the relationship between microbial community structure and function. The emphasis of this review is to describe microbial communities in digesters and quantitative and qualitative relationships between community structure and digester function. Progress has been made in the past few decades to identify key microorganisms influencing AD. Yet, more work is required to realize robust, quantitative relationships between microbial community structure and functions such as methane production rate and resilience after perturbations. Other promising areas of research for improved AD may include methods to increase/control (1) hydrolysis rate, (2) direct interspecies electron transfer to methanogens, (3) community structure–function relationships of methanogens, (4) methanogenesis via acetate oxidation, and (5) bioaugmentation to study community–activity relationships or improve engineered bioprocesses.

Characterization of a new thermophilic sulfate-reducing bacterium Thermodesulfovibrio yellowstonii, gen. nov. and sp. nov.: its phylogenetic relationship to Thermodesulfobacterium commune and their origins deep within the bacterial domain.

Abstract: A thermophilic sulfate-reducing vibrio isolated from thermal vent water in Yellowstone Lake, Wyoming, USA is described. The gram-negative, curved rod-shaped cells averaged 0.3 micrometer wide and 1.5 micrometers long. They were motile by means of a single polar flagellum. Growth was observed between 40 degrees and 70 degrees C with optimal growth at 65 degrees C. Cultures remained viable for one year at 27 degrees C although spore-formation was not observed. Sulfate, thiosulfate and sulfite were used as electron acceptors. Sulfur, fumarate and nitrate were not reduced. In the presence of sulfate, growth was observed only with lactate, pyruvate, hydrogen plus acetate, or formate plus acetate. Pyruvate was the only compound observed to support fermentative growth. Pyruvate and lactate were oxidized to acetate. Desulfofuscidin and c-type cytochromes were present. The G + C content was 29.5 mol%. The divergence in the 16 S ribosomal RNA sequences between the new isolate and Thermodesulfobacterium commune suggests that these two thermophilic sulfate-reducing bacteria represent different genera. These two bacteria depict a lineage that branches deeply within the Bacteria domain and which is clearly distinct from previously defined phylogenetic lines of sulfate-reducing bacteria. Strain YP87 is described as the type strain of the new genus and species Thermodesulfovibrio yellowstonii.

Trends in the development of environmentally friendly fouling-resistant marine coatings

Abstract: 'Marine biofouling', the undesired growth of marine organisms such as microorganisms, barnacles and seaweeds on submerged surfaces, is a global problem for maritime industries, with both economic and environmental penalties. The primary strategy for combating marine fouling is to use biocide-containing paints, but environmental concerns and legislation are driving science and technology towards non-biocidal solutions based solely on physico-chemical and materials properties of coatings. Advances in nanotechnology and polymer science, and the development of novel surface designs 'bioinspired' by nature, are expected to have a significant impact on the development of a new generation of environmentally friendly marine coatings.

Modern approaches to marine antifouling coatings

Abstract: Marine structures such as platforms, jetties and ship hulls are subject to diverse and severe biofouling. Methods for inhibiting both organic and inorganic growth on wetted substrates are varied but most antifouling systems take the form of protective coatings. Biofouling can negatively affect the hydrodynamics of a hull by increasing the required propulsive power and the fuel consumption. This paper reviews the development of antifouling coatings for the prevention of marine biological fouling. As a result of the 2001 International Maritime Organization (IMO) ban on tributyltin (TBT), replacement antifouling coatings have to be environmentally acceptable as well as maintain a long life. Tin-free self-polishing copolymer (SPC) and foul release technologies are current applications but many alternatives have been suggested. Modern approaches to environmentally effective antifouling systems and their performance are highlighted.

Promoting direct interspecies electron transfer with activated carbon

Abstract: Granular activated carbon (GAC) is added to methanogenic digesters to enhance conversion of wastes to methane, but the mechanism(s) for GAC's stimulatory effect are poorly understood. GAC has high electrical conductivity and thus it was hypothesized that one mechanism for GAC stimulation of methanogenesis might be to facilitate direct interspecies electron transfer (DIET) between bacteria and methanogens. Metabolism was substantially accelerated when GAC was added to co-cultures of Geobacter metallireducens and Geobacter sulfurreducens grown under conditions previously shown to require DIET. Cells were attached to GAC, but did not aggregate as they do when making biological electrical connections between cells. Studies with a series of gene deletion mutants eliminated the possibility that GAC promoted electron exchange via interspecies hydrogen or formate transfer and demonstrated that DIET in the presence of GAC did not require the electrically conductive pili and associated c-type cytochrome involved in biological interspecies electrical connections. GAC also greatly stimulated ethanol metabolism and methane production in co-cultures of G. metallireducens and Methanosarcina barkeri. Cells were attached to GAC, but not closely aggregated, suggesting little opportunity for biological electrical contacts between the species. GAC also enhanced methane production in samples from a methanogenic digester in which Methanosaeta were the predominant methanogens. The results demonstrate that GAC can promote DIET and suggest that stimulation of metabolism in methanogenic digesters can be attributed, at least in part, to the high conductivity of GAC providing better interspecies electrical connections than those that can be forged biologically.

Energetics of overall metabolic reactions of thermophilic and hyperthermophilic Archaea and Bacteria

Abstract: Thermophilic and hyperthermophilic Archaea and Bacteria have been isolated from marine hydrothermal systems, heated sediments, continental solfataras, hot springs, water heaters, and industrial waste They catalyze a tremendous array of widely varying metabolic processes As determined in the laboratory, electron donors in thermophilic and hyperthermophilic microbial redox reactions include H2, Fe(2+), H2S, S, S2O3(2-), S4O6(2-), sulfide minerals, CH4, various mono-, di-, and hydroxy-carboxylic acids, alcohols, amino acids, and complex organic substrates; electron acceptors include O2, Fe(3+), CO2, CO, NO3(-), NO2(-), NO, N2O, SO4(2-), SO3(2-), S2O3(2-), and S Although many assimilatory and dissimilatory metabolic reactions have been identified for these groups of microorganisms, little attention has been paid to the energetics of these reactions In this review, standard molal Gibbs free energies (DeltaGr(0)) as a function of temperature to 200 degrees C are tabulated for 370 organic and inorganic redox, disproportionation, dissociation, hydrolysis, and solubility reactions directly or indirectly involved in microbial metabolism To calculate values of DeltaGr(0) for these and countless other reactions, the apparent standard molal Gibbs free energies of formation (DeltaG(0)) at temperatures to 200 degrees C are given for 307 solids, liquids, gases, and aqueous solutes It is shown that values of DeltaGr(0) for many microbially mediated reactions are highly temperature dependent, and that adopting values determined at 25 degrees C for systems at elevated temperatures introduces significant and unnecessary errors The metabolic processes considered here involve compounds that belong to the following chemical systems: H-O, H-O-N, H-O-S, H-O-N-S, H-O-C(inorganic), H-O-C, H-O-N-C, H-O-S-C, H-O-N-S-C(amino acids), H-O-S-C-metals/minerals, and H-O-P For four metabolic reactions of particular interest in thermophily and hyperthermophily (knallgas reaction, anaerobic sulfur and nitrate reduction, and autotrophic methanogenesis), values of the overall Gibbs free energy (DeltaGr) as a function of temperature are calculated for a wide range of chemical compositions likely to be present in near-surface and deep hydrothermal and geothermal systems