Advances in Microbial Physiology最新文献

The diversity of microbial cells is reflected in differences in cell size and shape, motility, mechanisms of cell division, pathogenicity or adaptation to different environmental niches. All these variations are achieved by the distinct metabolic strategies adopted by the organisms. The respiratory chains are integral parts of those strategies especially because they perform the most or, at least, most efficient energy conservation in the cell. Respiratory chains are composed of several membrane proteins, which perform a stepwise oxidation of metabolites toward the reduction of terminal electron acceptors. Many of these membrane proteins use the energy released from the oxidoreduction reaction they catalyze to translocate charges across the membrane and thus contribute to the establishment of the membrane potential, i.e. they conserve energy. In this work we illustrate and discuss the composition of the respiratory chains of different taxonomic clades, based on bioinformatic analyses and on biochemical data available in the literature. We explore the diversity of the respiratory chains of Animals, Plants, Fungi and Protists kingdoms as well as of Prokaryotes, including Bacteria and Archaea. The prokaryotic phyla studied in this work are Gammaproteobacteria, Betaproteobacteria, Epsilonproteobacteria, Deltaproteobacteria, Alphaproteobacteria, Firmicutes, Actinobacteria, Chlamydiae, Verrucomicrobia, Acidobacteria, Planctomycetes, Cyanobacteria, Bacteroidetes, Chloroflexi, Deinococcus-Thermus, Aquificae, Thermotogae, Deferribacteres, Nitrospirae, Euryarchaeota, Crenarchaeota and Thaumarchaeota.

Hydrogenase enzymes are currently under the international research spotlight due to emphasis on biologically produced hydrogen as one potential energy carrier to relinquish the requirement for 'fossil fuel' derived energy. Three major classes of hydrogenase exist in microbes all able to catalyze the reversible oxidation of dihydrogen to protons and electrons. These classes are defined by their active site metal content: [NiFe]-; [FeFe]- and [Fe]-hydrogenases. Of these the [NiFe]-hydrogenases have links to ancient forms of metabolism, utilizing hydrogen as the original source of reductant on Earth. This review progresses to highlight the Group 4 [NiFe]-hydrogenase enzymes that preferentially generate hydrogen exploiting various partner enzymes or ferredoxin, while in some cases translocating ions across biological membranes. Specific focus is paid to Group 4A, the Formate hydrogenlyase complexes. These are the combination of a six or nine subunit [NiFe]-hydrogenase with a soluble formate dehydrogenase to derived electrons from formate oxidation for proton reduction. The incidence, physiology, structure and biotechnological application of these complexes will be explored with attention on Escherichia coli Formate Hydrogenlyase-1 (FHL-1).

Pseudomonas aeruginosa, a Gram-negative bacterium, is characterized by its versatility that enables persistent survival under adverse conditions. It can grow on diverse energy sources and readily acquire resistance to antimicrobial agents. As an opportunistic human pathogen, it also causes chronic infections inside the anaerobic mucus airways of cystic fibrosis patients. As a strict respirer, P. aeruginosa can grow by anaerobic nitrate ( [Formula: see text] ) respiration. Nitric oxide (NO) produced as an intermediate during anaerobic respiration exerts many important effects on the biological characteristics of P. aeruginosa. This review provides information regarding (i) how P. aeruginosa grows by anaerobic respiration, (ii) mechanisms by which NO is produced under such growth, and (iii) bacterial adaptation to NO. We also review the clinical relevance of NO in the fitness of P. aeruginosa and the use of NO as a potential therapeutic for treating P. aeruginosa infection.

This review is an overview on marine bioactive peptides with promising activities for the development of alternative drugs to fight human pathologies. In particular, we focus on potentially prolific producers of peptides in microorganisms, including sponge-associated bacteria and marine photoautotrophs such as microalgae and cyanobacteria. Microorganisms are still poorly explored for drug discovery, even if they are highly metabolically plastic and potentially amenable to culturing. This offers the possibility of obtaining a continuous source of bioactive compounds to satisfy the challenging demands of pharmaceutical industries. This review targets peptides because of the variety of potent biological activities demonstrated by these molecules, including antiviral, antimicrobial, antifungal, antioxidant, anticoagulant, antihypertensive, anticancer, antidiabetic, antiobesity, and calcium-binding bioactivities. Several of these peptides have already gained recognition as effective drug agents in recent years. We also focus on cutting-edge omic approaches for the discovery of novel compounds for pharmacological applications. With rapid depletion of natural resources, omic technologies may be the solution to efficiently produce a vast variety of novel peptides with unique pharmacological potential.

With the advent of the global antimicrobial resistance (AMR) crisis, our arsenal of effective antibiotics is diminishing. The widespread use and misuse of antibiotics in human and veterinary medicine, compounded by the lack of novel classes of antibiotic in the pharmaceutical pipeline, has left a hole in our antibiotic armamentarium. Thus, alternatives to traditional antibiotics are being investigated, including two major groups of antibacterial agents, which have been extensively studied, phytochemicals and metals. Within these groups, there are several subclasses of compound/elements, including polyphenols and metal nanoparticles, which could be used to complement traditional antibiotics, either to increase their potency or extend their spectrum of activity. Alone or in combination, these antibacterial agents have been shown to be effective against a vast array of human and animal bacterial pathogens, including those resistant to licensed antibacterials. These alternative antibacterial agents could be a key element in our fight against AMR and provide desperately needed options, to veterinary and medical clinicians alike.