Envisioning a Bold Food Waste Policy for Maine: A Mixed-Methods Study into the Context of Landfill Diversion of Food Waste

Landfilled organics waste both natural and financial resources by discarding usable materials that could bolster food security programs and composting efforts. According to the Drawdown Project, one-third of the food we produce in the United States goes to the landfill without ever reaching someone’s plate, contributing to leachate at disposal sites and accounting for more greenhouse gasses than the entire airline industry. As communities across the state struggle to support the 1 in 6 Mainers experiencing food insecurity with dwindling financial resources and limited personnel, food waste diversion provides a local solution that bolsters resilience at low cost. The absence of bold food waste diversion policy in Maine is not due to a lack of successful examples nearby, as Vermont’s recent universal organics recycling policy has seen tremendous success both in diverting more than 53,000 tons of food waste per year and in yielding a 40% increase in food donations. However, Maine faces distinct logistical challenges that complicate efforts to scale up current local food waste diversion efforts such as regional population sparsity and staffing resource constraints. This thesis project examines how Vermont’s Universal Recycling Policy could inspire a path forward to a food waste diversion policy that would work for Maine. The analysis draws upon professional interviews, surveys sent to municipalities, and organizational reports to examine the barriers and assets at play in Maine’s journey toward a bold food waste diversion policy, culminating in suggestions that will work for Mainers

Explaining Variance in Crime Rates Among Florida Counties

What explains the variance in crime rates among Florida counties? Bivariate regression found that clearance rate had a statistically significant negative relationship with crime rate, and that the following variables had a statistically significant positive association with crime rate: law enforcement funding, population density, Hispanic population percent, the percent of males in the 18-39 range, and the percent of immigrants. It seems probable that law enforcement funding is actually dependent on crime rate rather than causing increases in crime rate: counties with higher crime rates likely spend more money on law enforcement to combat crime. To deal with significant multicollinearity, stepwise regression was used to determine which variables to include in the multivariate analysis. In this model, clearance rate had a statistically significant negative association with crime rate and the percent of males 18-39 and population density both had statistically significant positive relationships with crime rate

Methanotrophs and copper

Methanotrophs, cells that consume methane (CH 4 ) as their sole source of carbon and energy, play key roles in the global carbon cycle, including controlling anthropogenic and natural emissions of CH 4 , the second-most important greenhouse gas after carbon dioxide. These cells have also been widely used for bioremediation of chlorinated solvents, and help sustain diverse microbial communities as well as higher organisms through the conversion of CH 4 to complex organic compounds (e.g. in deep ocean and subterranean environments with substantial CH 4 fluxes). It has been well-known for over 30 years that copper (Cu) plays a key role in the physiology and activity of methanotrophs, but it is only recently that we have begun to understand how these cells collect Cu, the role Cu plays in CH 4 oxidation by the particulate CH 4 monooxygenase, the effect of Cu on the proteome, and how Cu affects the ability of methanotrophs to oxidize different substrates. Here we summarize the current state of knowledge of the phylogeny, environmental distribution, and potential applications of methanotrophs for regional and global issues, as well as the role of Cu in regulating gene expression and proteome in these cells, its effects on enzymatic and whole-cell activity, and the novel Cu uptake system used by methanotrophs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79061/1/j.1574-6976.2010.00212.x.pd

Uptake and effect of rare earth elements on gene expression in Methylosinus trichosporium OB3b

It is well known that Methylosinus trichosporium OB3b has two forms of methane monooxygenase (MMO) responsible for the initial conversion of methane to methanol, a cytoplasmic (soluble) methane monooxygenase and a membrane-associated (particulate) methane monooxygenase, and that copper strongly regulates expression of these alternative forms of MMO. More recently, it has been discovered that M. trichosporium OB3b has multiple types of the methanol dehydrogenase (MeDH), i.e. the Mxa-type MeDH (Mxa-MeDH) and Xox-type MeDH (Xox-MeDH), and the expression of these two forms is regulated by the availability of the rare earth element (REE), cerium. Here, we extend these studies and show that lanthanum, praseodymium, neodymium and samarium also regulate expression of alternative forms of MeDH. The effect of these REEs on MeDH expression, however, was only observed in the absence of copper. Further, a mutant of M. trichosporium OB3b, where the Mxa-MeDH was knocked out, was able to grow in the presence of lanthanum, praseodymium and neodymium, but was not able to grow in the presence of samarium. Collectively, these data suggest that multiple levels of gene regulation by metals exist in M. trichosporium OB3b, but that copper overrides the effect of other metals by an as yet unknown mechanism

Methanol Oxidation Genes in the Marine Methanotroph Methylomonas sp. Strain A4

Methanol dehydrogenase has been purified from the type I marine methanotroph Methylomonas sp. strain A4 and found to be similar to other methanol dehydrogenase enzymes in subunit composition, molecular mass, and N-terminal sequence of the two subunits. A heterologous gene probe and a homologous oligonucleotide have been used to identify a DNA fragment from Methylomonas sp. strain A4 which contains moxF, the gene encoding the large subunit of methanol dehydrogenase. Protein expression experiments with Escherichia coli, immunoblotting of expression extracts, and partial DNA sequence determination have confirmed the presence of moxF on this DNA fragment. In addition, expression and immunoblot experiments have shown the presence of the genes for the small subunit of methanol dehydrogenase (moxI) and for the methanol dehydrogenase-specific cytochrome c (moxG). The moxG gene product has been shown to be cytochrome c552. The expression experiments have also shown that two other genes are present on this DNA fragment, and our evidence suggests that these are the homologs of moxJ and moxR, whose functions are unknown. Our data suggest that the order of these genes in Methylomonas sp. strain A4 is moxFJGIR, the same as in the facultative methylotrophs. The transcriptional start site for moxF was mapped. The sequence 5' to the transcriptional start does not resemble other promoter sequences, including the putative moxF promoter sequence of facultative methylotrophs. These results suggest that although the order of these genes and the N-terminal amino acid sequence of MoxF and MoxI are conserved between distantly related methylotrophs, the promoters for this gene cluster differ substantially

Methylmercury uptake and degradation by methanotrophs

Methylmercury (CH3Hg+) is a potent neurotoxin produced by certain anaerobic microorganisms in natural environments. Although numerous studies have characterized the basis of mercury (Hg) methylation, no studies have examined CH3Hg+ degradation by methanotrophs, despite their ubiquitous presence in the environment. We report that some methanotrophs, such as Methylosinus trichosporium OB3b, can take up and degrade CH3Hg+ rapidly, whereas others, such as Methylococcus capsulatus Bath, can take up but not degrade CH3Hg+. Demethylation by M. trichosporium OB3b increases with increasing CH3Hg+ concentrations but was abolished in mutants deficient in the synthesis of methanobactin, a metal-binding compound used by some methanotrophs, such as M. trichosporium OB3b. Furthermore, addition of methanol (>5 mM) as a competing one-carbon (C1) substrate inhibits demethylation, suggesting that CH3Hg+ degradation by methanotrophs may involve an initial bonding of CH3Hg+ by methanobactin followed by cleavage of the C–Hg bond in CH3Hg+ by the methanol dehydrogenase. This new demethylation pathway by methanotrophs indicates possible broader involvement of C1-metabolizing aerobes in the degradation and cycling of toxic CH3Hg+ in the environment

Identification of intermediates of in vivo trichloroethylene oxidation by the membrane-associated methane monooxygenase

The rate and products of trichloroethylene (TCE) oxidation by Methylomicrobium album BG8 expressing membrane-associated methane monooxygenase (pMMO) were determined using 14 C radiotracer techniques. [ 14 C]TCE was degraded at a rate of 1.24 nmol (min mg protein) −1 with the initial production of glyoxylate and then formate. Radiolabeled CO 2 was also found after incubating M. album BG8 for 5 h with [ 14 C]TCE. Experiments with purified pMMO from Methylococcus capsulatus Bath showed that TCE could be mineralized to CO 2 by pMMO. Oxygen uptake studies verified that M. album BG8 could oxidize glyoxylate and that pMMO was responsible for the oxidation based on acetylene inactivation studies. Here we propose a pathway of TCE oxidation by pMMO-expressing cells in which TCE is first converted to TCE-epoxide. The epoxide then spontaneously undergoes HCl elimination to form glyoxylate which can be further oxidized by pMMO to formate and CO 2 .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74667/1/j.1574-6968.2000.tb09090.x.pd

Dichloromethane and trichloroethylene inhibition of methane oxidation by the membrane-associated methane monooxygenase of Methylosinus trichosporium OB3b

Whole-cell assays were used to measure the effect of dichloromethane and trichloroethylene on methane oxidation by Methylosinus trichosporium OB3b synthesizing the membrane-associated or particulate methane monooxygenase (pMMO). For M. trichosporium OB3b grown with 20 μM copper, no inhibition of methane oxidation was observed in the presence of either dichloromethane or trichloroethylene. If 20 mM formate was added to the reaction vials, however, methane oxidation rates increased and inhibition of methane oxidation was observed in the presence of dichloromethane and trichloroethylene. In the presence of formate, dichloromethane acted as a competitive inhibitor, while trichloroethylene acted as a noncompetitive inhibitor. The finding of noncompetitive inhibition by trichloroethylene was further examined by measuring the inhibition constants K iE and K iES . These constants suggest that trichloroethylene competes with methane at some sites, although it can bind to others if methane is already bound. Whole-cell oxygen uptake experiments for active and acetylene-treated cells also showed that provision of formate could stimulate both methane and trichloroethylene oxidation and that trichloroethylene did not affect formate dehydrogenase activity. The finding that different chlorinated hydrocarbons caused different inhibition patterns can be explained by either multiple substrate binding sites existing in pMMO or multiple forms of pMMO with different activities. The whole-cell analysis performed here cannot distinguish between these models, and further work should be done on obtaining active preparations of the purified pMMO.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41917/1/203-171-5-301_91710301.pd