Publications by authors named "But S"

This study employs a novel fuzzy logic-based framework to address multi-attribute group decision-making problems commonly encountered in modern astronomy. Our approach utilizes the probabilistic linguistic -rung orthopair fuzzy set (PL-ROFS) to handle the inherent uncertainties associated with astronomical data. The PL-ROFS offers significant advantages over existing fuzzy sets like probabilistic hesitant, linguistic intuitionistic, and linguistic Pythagorean fuzzy sets, which comprise both stochastic and non-stochastic uncertainties simultaneously.

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Considering the increasing interest in understanding the biotic component of methane removal from our atmosphere, it becomes essential to study the physiological characteristics and genomic potential of methanotroph isolates, especially their traits allowing them to adapt to elevated growth temperatures. The genetic signatures of species have been detected in many terrestrial and aquatic ecosystems. A small set of representatives of this genus has been isolated and maintained in culture.

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The genome of aerobic methanotroph Methylococcus capsulatus Bath possesses genes of three biochemical pathways of C1-carbon assimilation: the ribulose monophosphate cycle, the Calvin-Benson-Bassham cycle, and the partial serine cycle. Numerous studies have demonstrated that during methanotrophic growth cells of Methylococcus capsulatus Bath express key enzymes of these routes. In this study, the role of the serine cycle key enzymes, serine-glyoxylate aminotransferase (Sga) and malyl-CoA lyase (Mcl) in metabolism of Methylococcus capsulatus Bath was investigated by gene inactivation.

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(1) Background: Early signs of sepsis in a neonate are often subtle and non-specific, the clinical course rapid and fulminant. The aim of our research was to analyse diagnostic markers for neonatal sepsis and build an application which could calculate its probability. (2) Methods: A retrospective clinical study was conducted on 497 neonates treated at the Clinical Department of Neonatology of the University Children's Hospital in Ljubljana from 2007 to 2021.

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The genus Methylomonas accommodates strictly aerobic, obligate methanotrophs, with their sole carbon and energy sources restricted to methane and methanol. These bacteria inhabit oxic-anoxic interfaces of various freshwater habitats and have attracted considerable attention as potential producers of a single-cell protein. Here, we characterize two fast-growing representatives of this genus, strains 12 and MP1, which are phylogenetically distinct from the currently described Methylomonas species (94.

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The bacterial genus , which comprises aerobic thermotolerant methanotrophic cocci, was described half-a-century ago. Over the years, a member of this genus, Bath, has become a major model organism to study genomic and metabolic basis of obligate methanotrophy. High biotechnological potential of fast-growing species, mainly as a promising source of feed protein, has also been recognized.

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Objectives: Alteration of the cofactor specificity of acrylyl-CoA reductase (AcuI) catalyzing the NAD(P)H-dependent reduction of acrylyl-CoA to propionyl-CoA is often desirable for designing of artificial metabolic pathways of various appointments.

Results: Several variants of AcuIs from Escherichia coli K-12 with multiple amino acid substitutions to alter the cofactor preference were obtained by site directed mutagenesis and the modified enzymes as His-tagged proteins were characterized. The simultaneous substitutions of arginine-180, arginine-198 and serine-178 residues by alanine in the enzyme pocket sequence as well as other amino acid changes decreased both NADPH- and NADH-dependent activities in comparison to the wild-type enzyme.

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Objective: To determine the prevalence of lower urinary tract symptoms (LUTS) in female adolescent population.

Study Design: We performed a questionnaire-based study in nine randomly selected high schools in our country. Our primary aim was to evaluate the prevalence of certain LUTS in adolescent girls: frequency, urgency, nocturia, feeling of incomplete bladder emptying, dysuria, and urinary incontinence.

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Global methane emissions have been steadily increasing over the past few decades, exerting a negative effect on the environment. Biogas from landfills and sewage treatment plants is the main anthropogenic source of methane. This makes methane bioconversion one of the priority areas of biotechnology.

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The biochemical routes for assimilation of one-carbon compounds in bacteria require many clarifications. In this study, the role of malyl-CoA lyase in the metabolism of the aerobic type I methanotroph Methylotuvimicrobium alcaliphilum 20Z has been investigated by gene inactivation and biochemical studies. The functionality of the enzyme has been confirmed by heterologous expression in Escherichia coli.

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Background: Microorganisms living in saline environments are forced to regulate turgor via the synthesis of organic osmoprotective compounds. Microbial adaptation to fluctuations in external salinity includes degradation of compatible solutes. Here we have examined the biochemical pathway of degradation of the cyclic imino acid ectoine, the major osmoprotector in halotolerant methane-utilizing bacteria.

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The bacteria utilizing methane as a growth substrate (methanotrophs) are important constituents of the biosphere. Methanotrophs mitigate the emission of anthropogenic and natural greenhouse gas methane to the environment and are the promising agents for future biotechnologies. Many aspects of CH4 bioconversion by methanotrophs require further clarification.

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Recombinant malic enzyme from the aerobic methanotroph Methylosinus trichosporium was obtained by heterologous expression in Escherichia coli and purified by affinity metal-chelating chromatography. The homohexameric enzyme of 6×80 kDa catalyzed the reversible reaction of oxidative decarboxylation of malate to pyruvate in the presence of mono- and divalent cations and NADP+ as a cofactor. The k/K ratio indicated much higher catalytic efficiency of the malate decarboxylation reaction as compared with the pyruvate carboxylation reaction.

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This review is focused on recent studies of carbon metabolism in aerobic methanotrophs that specifically addressed the properties, distribution and phylogeny of some of the key enzymes involved in assimilation of carbon from methane. These include enzymes involved in sugar sythesis and cleavage, conversion of intermediates of the tricarboxylic acid cycle, as well as in osmoadaptation in halotolerant methanotrophs.

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The indicator enzyme of the serine pathway of assimilation of reduced C compounds, serine-glyoxylate aminotransferase (Sga), has been purified from three methane-oxidizing bacteria, Methylomicrobium alcaliphilum 20Z, Methylosinus trichosporium OB3b and Methylococcus capsulatus Bath. The native enzymes were shown to be dimeric (80 kDa, strain 20Z), tetrameric (~ 170 kDa, strain OB3b) or trimeric (~ 120 kDa, strain Bath). Sga from the three methanotrophs catalyse the pyridoxal phosphate-dependent transfer of an amino group from serine to glyoxylate and pyruvate; the enzymes from strains 20Z and Bath also transfer an amino group from serine to α-ketoglutarate and from alanine to glyoxylate.

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Anaerobic digestion (AD) of waste substrates, and renewable biomass and crop residues offers a means to generate energy-rich biogas. However, at present, AD-derived biogas is primarily flared or used for combined heat and power (CHP), in part due to inefficient gas-to-liquid conversion technologies. Methanotrophic bacteria are capable of utilizing methane as a sole carbon and energy source, offering promising potential for biological gas-to-liquid conversion of AD-derived biogas.

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Four enzymes involved in sucrose metabolism: sucrose phosphate synthase (Sps), sucrose phosphate phosphatase (Spp), sucrose synthase (Sus) and fructokinase (FruK), were obtained as his-tagged proteins from the moderately thermophilic methanotroph Methylocaldum szegediense O12. Sps, Spp, FruK and Sus demonstrated biochemical properties similar to those of other bacterial counterparts, but the translated amino acid sequences of Sps and Spp displayed high divergence from the respective microbial enzymes. The Sus of M.

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In the aerobic methanotrophic bacteria Methylomicrobium alcaliphilum 20Z, Methylococcus capsulatus Bath, and Methylosinus trichosporium OB3b, the biochemical properties of hydroxypyruvate reductase (Hpr), an indicator enzyme of the serine pathway for assimilation of reduced C-compounds, were comparatively analyzed. The recombinant Hpr obtained by cloning and heterologous expression of the hpr gene in Escherichia coli catalyzed NAD(P)H-dependent reduction of hydroxypyruvate or glyoxylate, but did not catalyze the reverse reactions of D-glycerate or glycolate oxidation. The absence of the glycerate dehydrogenase activity in the methanotrophic Hpr confirmed a key role of the enzyme in utilization of C-compounds via the serine cycle.

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Two key enzymes of the ribulose monophosphate (RuMP) cycle for formaldehyde fixation, 3-hexulose-6-phosphate synthase (HPS) and 6-phospho-3-hexulose isomerase (PHI), in the aerobic halotolerant methanotroph Methylomicrobium alcaliphilum 20Z are encoded by the genes hps and phi and the fused gene hps-phi. The recombinant enzymes HPS-His, PHI-His, and the two-domain protein HPS-PHI were obtained by heterologous expression in Escherichia coli and purified by affinity chromatography. PHI-His, HPS-His (2 × 20 kDa), and the fused protein HPS-PHI (2 × 40 kDa) catalyzed formation of fructose 6-phosphate from formaldehyde and ribulose-5-phosphate with activities of 172 and 22 U/mg, respectively.

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A number of vectors were constructed based on the plasmid from the broad range of pMHA200 hosts. Also, the expression of some key genes of the haloalkalitolerant methanotroph Methylomicrobium alcaliphilum 20Z was studied. The activities of the promoter regions of genes for hexulose phosphate synthase, glutamine synthetase, and glucokinase, as well as the promoter of the ectABC-ask operon, which encodes enzymes for osmoprotectant ectoine biosynthesis, were evaluated with the use of the gfp gene; the evaluation was proven to be ineffective.

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Sucrose accumulation has been observed in some methylotrophic bacteria utilizing methane, methanol, or methylated amines as a carbon and energy source. In this work, we have investigated the biochemical pathways for sucrose metabolism in the model halotolerant methanotroph Methylomicrobium alcaliphilum 20Z. The genes encoding sucrose-phosphate synthase (Sps), sucrose-phosphate phosphatase (Spp), fructokinase (FruK), and amylosucrase (Ams) were co-transcribed and displayed similar expression levels.

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The aerobic obligate methylotroph Methylobacillus flagellatus KT was shown to synthesize sucrose in the presence of 0.5-2% NaCl in the growth medium. In the genome of this bacterium, an open reading frame (ORF) encoding a predicted 84-kD polypeptide homologous to the plant and cyanobacterial sucrose phosphate synthases (SPSs) was found.

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In the cluster of genes for sucrose biosynthesis and cleavage in Methylomicrobium alcaliphilum 20Z, a gene whose encoded sequence showed high similarity to sugar kinases of the ribokinase family was found. By heterologous expression of this gene in Escherichia coli cells and following metal chelate affinity chromatography, the electrophoretically homogenous recombinant enzyme with six histidine residues on the C-end was obtained. The enzyme catalyzes ATP-dependent phosphorylation of fructose into fructose-6-phosphate but is not active with other sugars as phosphoryl acceptors.

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Spectrophotometric determination of molybdenum(VI) and tungsten(VI) with application of Artificial Neural Networks is proposed and it was applied for elemental analysis of solid polyoxometalates. Better results in comparison with previously those achieved by previous published method were demonstrated. MALDI-TOF Mass Spectrometry was tested for possible determination of molecular weight of polyoxometalates utilizing different matrices.

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