The species distribution of some naturally-occurring quaternary ammonium compounds

Metaproteomics reveals methyltransferases implicated in dichloromethane and glycine betaine fermentation by 'Candidatus Formimonas warabiya' strain DCMF

Dichloromethane (DCM; CH₂Cl₂) is a widespread pollutant with anthropogenic and natural sources. Anaerobic DCM-dechlorinating bacteria use the Wood-Ljungdahl pathway, yet dechlorination reaction mechanisms remain unclear and the enzyme(s) responsible for carbon-chlorine bond cleavage have not been definitively identified. Of the three bacterial taxa known to carry out anaerobic dechlorination of DCM, 'Candidatus Formimonas warabiya' strain DCMF is the only organism that can also ferment non-chlorinated substrates, including quaternary amines (i.e., choline and glycine betaine) and methanol. Strain DCMF is present within enrichment culture DFE, which was derived from an organochlorine-contaminated aquifer. We utilized the metabolic versatility of strain DCMF to carry out comparative metaproteomics of cultures grown with DCM or glycine betaine. This revealed differential abundance of numerous proteins, including a methyltransferase gene cluster (the mec cassette) that was significantly more abundant during DCM degradation, as well as highly conserved amongst anaerobic DCM-degrading bacteria. This lends strong support to its involvement in DCM dechlorination. A putative glycine betaine methyltransferase was also discovered, adding to the limited knowledge about the fate of this widespread osmolyte in anoxic subsurface environments. Furthermore, the metagenome of enrichment culture DFE was assembled, resulting in five high quality and two low quality draft metagenome-assembled genomes. Metaproteogenomic analysis did not reveal any genes or proteins for utilization of DCM or glycine betaine in the cohabiting bacteria, supporting the previously held idea that they persist via necromass utilization.

An NMR-Based Metabolomics Assessment of the Effect of Combinations of Natural Feed Items on Juvenile Red Drum, Sciaenops ocellatus

This study evaluated the effects of seven diets composed of natural feed components (chopped fish, shrimp, and squid) alone or in combination on the liver metabolite profile of juvenile red drum (Sciaenops ocellatus) cultured in a 24-tank recirculating aquaculture system over the course of 12 weeks using Nuclear Magnetic Resonance (NMR)-based metabolomics. Experimental diets included fish (F), shrimp (SH), squid (SQ), fish and shrimp (FSH), fish and squid (FSQ), shrimp and squid (SHSQ), fish, shrimp, and squid (FSHSQ). A commercial fishmeal-based pelleted diet was used as a control. Fish were fed isocalorically. Red drum liver samples were collected at five different time points: T0, before the start of the trial (n = 12), and subsequently every 3 weeks over the course of 12 weeks (T3, T6, T9, T12), with n = 9 fish/diet/time point. Polar liver extracts were analyzed by NMR-based metabolomics. Multivariate statistical analyses (PCA, PLS-DA) revealed that red drum fed the F diet had a distinct liver metabolite profile from fish fed the other diets, with those fed SH, SQ and the combination diets displaying greater similarities in their metabolome. Results show that 19 metabolites changed significantly among the different dietary treatments, including amino acids and amino acid derivatives, quaternary amines and methylamines, carbohydrates and phospholipids. Specifically, γ-butyrobetaine, N-formimino-L-glutamate (FIGLU), sarcosine and beta-alanine were among the most discriminating metabolites. Significant correlations were found between metabolites and six growth performance parameters (final body weight, total length, condition factor, liver weight, hepatosomatic index, and eviscerated weight). Metabolites identified in this study constitute potential candidates for supplementation in fish feeds for aquaculture and optimization of existing formulations. Additionally, we identified a quaternary amine, γ-butyrobetaine as a potential biomarker of shrimp consumption in red drum. These results warrant further investigation and biomarker validation and have the potential for broader applicability outside of the aquaculture field in future investigations in wild red drum populations and potentially other carnivorous marine fishes.

Novel dichloromethane-fermenting bacteria in the Peptococcaceae family

Dichloromethane (DCM; CH2Cl2) is a toxic groundwater pollutant that also has a detrimental effect on atmospheric ozone levels. As a dense non-aqueous phase liquid, DCM migrates vertically through groundwater to low redox zones, yet information on anaerobic microbial DCM transformation remains scarce due to a lack of cultured organisms. We report here the characterisation of DCMF, the dominant organism in an anaerobic enrichment culture (DFE) capable of fermenting DCM to the environmentally benign product acetate. Stable carbon isotope experiments demonstrated that the organism assimilated carbon from DCM and bicarbonate via the Wood-Ljungdahl pathway. DCMF is the first anaerobic DCM-degrading population also shown to metabolise non-chlorinated substrates. It appears to be a methylotroph utilising the Wood-Ljungdahl pathway for metabolism of methyl groups from methanol, choline, and glycine betaine. The flux of these substrates from subsurface environments may either directly (DCM, methanol) or indirectly (choline, glycine betaine) affect the climate. Community profiling and cultivation of cohabiting taxa in culture DFE without DCMF suggest that DCMF is the sole organism in this culture responsible for substrate metabolism, while the cohabitants persist via necromass recycling. Genomic and physiological evidence support placement of DCMF in a novel genus within the Peptococcaceae family, 'Candidatus Formimonas warabiya'.

The teleost fish, blue gourami Trichopodus trichopterus, distinguishes the taste of chemically similar substances

Behavioural approaches permit studies of the functional features of animal gustatory systems at the organism level, but they are seldom used compared to molecular and electrophysiological methods. This imbalance is particularly apparent in studies on fish gustation. Consequently, our notion of taste preferences remains limited in fish, the most numerous and diverse group of vertebrates. The present study aimed to determine whether fish could distinguish the tastes of chemical substances with similar structures and configurations. We performed behavioural trials, where each test substance (L-alanine, glycine, L-cysteine and 9 of their derivatives; 0.1 M) was incorporated into agar pellets, and presented to blue gourami (Trichopodus trichopterus). We found that L-α-, L-β-, and D-α-alanine as well as L-cysteine and L-cystine had different palatabilities; and glycine, methyl-glycine, dimethyl-glycine-HCl, trimethyl-glycine, and glycyl-glycine had similar taste qualities. Results show that molecular transformation could shift the palatability of amino acids, which led to changes in the orosensory behaviour of blue gourami. The ability of fish to display different taste preferences for substances, like amino acids and their, derivetives, widely distributed among aquatic organisms, undoubtedly forms the sensory basis for selective feeding, which in turn, reduces the competition for food among sympatric species in natural waters.

Sensory cutaneous papillae in the sea lamprey (Petromyzon marinus L.): I. Neuroanatomy and physiology

Molecules present in an animal's environment can indicate the presence of predators, food, or sexual partners and consequently, induce migratory, reproductive, foraging, or escape behaviors. Three sensory systems, the olfactory, gustatory, and solitary chemosensory cell (SCC) systems detect chemical stimuli in vertebrates. While a great deal of research has focused on the olfactory and gustatory system over the years, it is only recently that significant attention has been devoted to the SCC system. The SCCs are microvillous cells that were first discovered on the skin of fish, and later in amphibians, reptiles, and mammals. Lampreys also possess SCCs that are particularly numerous on cutaneous papillae. However, little is known regarding their precise distribution, innervation, and function. Here, we show that sea lampreys (Petromyzon marinus L.) have cutaneous papillae located around the oral disk, nostril, gill pores, and on the dorsal fins and that SCCs are particularly numerous on these papillae. Tract-tracing experiments demonstrated that the oral and nasal papillae are innervated by the trigeminal nerve, the gill pore papillae are innervated by branchial nerves, and the dorsal fin papillae are innervated by spinal nerves. We also characterized the response profile of gill pore papillae to some chemicals and showed that trout-derived chemicals, amino acids, and a bile acid produced potent responses. Together with a companion study (Suntres et al., Journal of Comparative Neurology, this issue), our results provide new insights on the function and evolution of the SCC system in vertebrates.

Hard coral (Porites lobata) extracts and homarine on cytochrome P450 expression in Hawaiian butterflyfishes with different feeding strategies

Dietary specialists tend to be less susceptible to the effects of chemical defenses produced by their prey compared to generalist predators that feed upon a broader range of prey species. While many researchers have investigated the ability of insects to detoxify dietary allelochemicals, little research has been conducted in marine ecosystems. We investigated metabolic detoxification pathways in three species of butterflyfishes: the hard coral specialist feeder, Chaetodon multicinctus, and two generalist feeders, Chaetodon auriga and Chaetodon kleinii. Each species was fed tissue homogenate of the hard coral Porites lobata or the feeding deterrent compound homarine (found in the coral extract), and the expression and catalytic activity of cytochrome P450 (CYP) 3A-like and CYP2-like enzymes were examined after one-week of treatment. The P. lobata homogenate significantly induced content and catalytic activity of CYP2-like and CYP3A-like forms, by 2-3 fold and by 3-9 fold, respectively, in C. multicinctus. Homarine caused a significant decrease of CYP2-like and CYP3A-like proteins at the high dose in C. kleinii and 60-80% mortality in that species. Homarine also induced CYP3A-like content by 3-fold and catalytic activity by 2-fold in C. auriga, while causing non-monotonic increases in CYP2-like and CYP3A-like catalytic activity in C. multicinctus. Our results indicate that dietary exposure to coral homogenates and the feeding deterrent constituent within these homogenates caused species-specific modulation of detoxification enzymes consistent with the prey selection strategies of generalist and specialist butterflyfishes.

Metabolism of trimethylamine, choline, and glycine betaine by sulfate-reducing and methanogenic bacteria in marine sediments

The response of methanogenesis and sulfate reduction to trimethylamine, choline, and glycine betaine was examined in surface sediments from the intertidal region of Lowes Cove, Maine. Addition of these substrates markedly stimulated methanogenesis in the presence of active sulfate reduction, whereas addition of other substrates, including glucose, acetate, and glycine, had no effect on methane production. Sulfate reduction was stimulated simultaneously with methanogenesis by the various quaternary amines and all other substrates examined. Incubation of exogenous trimethylamine, choline, or glycine betaine with either bromoethane sulfonic acid or sodium molybdate was used to establish pathways of degradation of the substrates. Methanogenesis dominated the metabolism of trimethylamine, although limited nonmethanogenic activity, perhaps by sulfate-reducing bacteria, was observed. Acetate was oxidized primarily by sulfate reducers. Both choline and glycine betaine were fermented stoichiometrically to acetate and trimethylamine; apparently, neither substrate could be utilized directly by methanogens or sulfate reducers, and the activities of fermenters, methanogens, and sulfate reducers were all required to effect complete mineralization. These observations support the hypothesis that the presence of quaternary amines can mediate the coexistence of sulfate reduction and methanogenesis in marine surface sediments; they also implicate methanogens in the nitrogen cycle of marine sediments containing quaternary amines.

Treatment of waste gas containing diethyldisulphide (DEDS) in a bench scale biofilter

Waste gas containing diethyldisulphide (DEDS) is generated from various industries including pulp and paper, refinery, rayon and molasses based distilleries, etc. DEDS has odour threshold detection with an average concentration of 10(-9)mg/m(3) at 25 degrees C. DEDS is toxic to bacteria, fungus and also to mammals when exposed for a long period. Waste gas containing DEDS require proper treatment prior to discharge into the environment. DEDS containing waste gas was treated in a biofilter, packed with compost along with wooden chips and enriched with DEDS degrading microorganisms. The biofilter could remove DEDS to the extent of 94+/-5% at a loading of 1.60 g/m(3)/h with an empty bed retention time of 150s. At optimal operating conditions, the average moisture content required by the biofilter was in the range of 60-65%. The biodegradative products of DEDS were thiosulphate and sulphate.

Treatment of waste gas containing monomethylamine in a biofilter enriched with Pseudomonas mendocina

Waste gas containing monomethylamine (MMA) was treated in a biofilter packed with compost along with wood chips and enriched with Pseudomonas mendocina. The biofilter could remove MMA to the extent of more than 99% at a loading of 42.36 gm(-3)h(-1) with an empty bed retention time of 12s. At optimal operating conditions, the moisture content in the biofilter was maintained at around 45%. The biodegradative products of MMA were ammonia, nitrite, and nitrate.

TMAO and other organic osmolytes in the muscles of amphipods (Crustacea) from shallow and deep water of Lake Baikal

Concentrations of trimethylamine oxide (TMAO) and other 'compatible' osmolytes were analyzed in the muscle tissue of Lake Baikal amphipods (Crustacea) in relation to water depth of the freshwater Lake Baikal. Using HPLC and mass spectrometry, glycerophosphoryl choline (GPC), betaine, S-methyl-cysteine, sarcosine, and taurine were detected for the first time in freshwater amphipods. These osmolytes were frequently found in the five species studied but mixtures were too complex to be quantified. The pattern of these osmolytes did not change with respect to water depth. The TMAO concentration, however, was significantly higher in the muscle tissue of amphipods living in deep water than of those living in shallow water, which supports the hypothesis that TMAO acts as a protective osmolyte at increased hydrostatic pressure. We propose that eurybathic amphipods, exposed to raised hydrostatic pressure in the extremely deep freshwater Lake Baikal, have elevated TMAO levels to counteract the adverse effect of high pressure on protein structure. The elevated intracellular osmotic pressure is balanced by upregulating the extracellular hemolymph NaCl concentration.

Biosynthesis and role in osmoregulation of glycine-betaine in the Mediterranean mussel Mytilus galloprovincialis LMK

Quaternary bases, for example glycine-betaine, are difficult to quantify in biological materials because of a lack of specificity. However, nuclear magnetic resonance (NMR) can determine quaternary bases even in the presence of high water concentrations. Using NMR concentrations of glycine-betaine, the posterior adductor muscle of the Mediterranean mussel Mytilus galloprovincialis were measured up to 256 micromole/g dry weight. These concentrations were related to external salinity concentrations. The biosynthesis of glycine-betaine was demonstrated in M. galloprovincialis from the precursor (14)C choline.

Homarine, a common metabolite in edible Mediterranean molluscs: occurrence, spectral data and revision of a related structure

Homarine was isolated from nine edible species of marine molluscs belonging to classes Gastropoda, Bivalvia, and Cephalopoda. A thorough chromatographic, NMR and MS study provided evidence that homarine is a common and abundant metabolite of all these species. This study casts doubt on a previous assertion that 1,1'-dimethyl-[2,2']-bipyridinium is a metabolite of the Bivalve Callista chione.

Novel betaines from the marine sponge Agelas dispar

Three novel betaine alkaloids, called aminozooanemonin (1), pyridinebetaine A (2), and pyridinebetaine B (3), have been isolated from the Caribbean sponge Agelas dispar. Their structures were determined by FABMS, IR, UV, and 1D and 2D NMR spectroscopic experiments. Aminozooanemonin and pyridinebetaine A showed moderate antibacterial activity.

Evidence that Escherichia coli accumulates glycine betaine from marine sediments

Escherichia coli grew faster in autoclaved marine sediment than in seawater alone. When E. coli was cultivated in sediment diluted with minimal medium M63 at 0.6 M NaCl, supplemented or not supplemented with glucose or with seawater, the osmoprotector glycine betaine was accumulated in the cells. The best growth occurred on glucose. Accumulation of glycine betaine was not observed with E. coli was grown in sterile seawater alone. The fact that E. coli grew better in the sediments than in seawater is attributed somewhat to the high content of organic matter in the sediment but mainly to the accumulation of glycine betaine. Thus, osmoprotection should be considered to be an additional factor in bacterial survival in estuarine sediments.

The composition of animal cells: solutes contributing to osmotic pressure and charge balance

The cytoplasmic solutes of vertebrates and invertebrates, other than Na, K and Cl, are surveyed in relation to their influence on ionic regulation through osmolality and charge balance. The most abundant include MgATP, phosphagens, amino acids, various other nitrogen and phosphorus compounds and sometimes anaerobic end products and antifreeze agents. Differences in muscle osmolality, e.g. between marine and non-marine animals, affect mainly nitrogenous solutes of no net charge, such as certain amino acids, taurine, betaine, trimethylamine oxide and urea. The high osmolality of axoplasm in marine invertebrates is due more to anions such as aspartate, glutamate and isethionate.