Inhibition of methane formation from municipal refuse in laboratory scale lysimeters

Changes in chemical composition and population development of key groups of bacteria (hydrolytic, acetogenic, and methanogenic) were measured in a laboratory scale simulation of refuse decomposition from the time of initial incubation through the methane production phase. Inhibition of methane production appeared to be characteristic of refuse decomposition. It was observed in 20 of 32 leachate recycle containers and all 19 control containers. Inhibition was not owing to an absence of indigenous microorganisms, toxic concentrations of carboxylic acids or cations, or insufficient ammonia. Characteristics of inhibited and successful containers are compared.     

Double immunogold labelling demonstrating expression of recombinant genes for production of an anti-fertility vaccine

The multiple antibody technique for double immunogold labelling for the simultaneous localization of two antigens with negative staining was utilized to demonstrate the expression of recombinant genes in bacteria, with the primary antibodies being raised in different host species. For the production of a vaccine for immunological control of fertility, a multi-functional plasmid vector was introduced into the bacterium Pseudomonas aeruginosa containing the Dichelobacter nodosus fimbrial subunit gene with a grafted amino acid sequence of luteinizing hormone releasing hormone (LHRH) peptide. Fimbriae of this recombinant, when run on a SDC-polyacrylamide electrophoresis gel, gave a single broad band for LHRH peptide/D. nodosus subunit and were harvested to produce the anti-fertility vaccine which, when injected into mice, produced atrophy of the testes with absence of sperm, resulting in reversible castration. Double immunogold labelling of the recombinant P. aeruginosa bacteria demonstrated fimbriae with strong expression of the LHRH-peptide, expression of the D. nodosus subunit and absence of host fimbriae.     

Spectral Properties of Bacteriochlorophyll c in Organisms and in Model Systems

Polarized absorption and fluorescence spectra of bacteriochlorophyll c and green photosynthetic bacterium Prostheecochloris aestuarii cells and cell fragments embedded in stretched polymer film were measured. In pigment samples the artificial oligomers of bacteriochlorophyll c (with absorption about 750 nm) and other forms of this pigment and bacteriopheophytin (with absorption at 670 nm) were present. In bacteria samples, embedded in polymer, oligomers were in high degree disaggregated and as a result the absorption about 670 nm was observed. Previously for similar sets of samples the decay of fluorescence excited only at one wavelength was analyzed on three exponential components, but exact lifetime values of these components for various samples were different. The aim of present paper was to check if these differences occur because of various contributions to decay from three well defined forms or if they were related to the existence of several pigment forms with slightly different lifetimes. The global analysis of data obtained for various excitation and observation wavelengths of fluorescence were done. From this analysis it follows that the second situation occurs. For a model system containing artificial oligomers the largest component of decay has a ⁴ of about 0.183 ns or 0.136 ns depending on observation wavelength. For the bacteria sample, in which the emission at 680 nm is the superposition from various pigments, global analysis done for various excitation wavelengths shows also that the values differ depending on the regions of fluorescence observation. From polarized spectra, it follows that in the model system the pigments absorbing at 670 nm are randomly distributed whereas oligomers are highly oriented. In bacteria fragments absorbing at 670 nm pigment molecules can be divided into two groups: one oriented along the axis of film stretching and the second practically randomly distributed. In living organisms, under some conditions, small amount of 670 nm pigments can be present and can work as excitation energy traps or as antenna transferring the excitation. Present results show that the role of various pools of 670 nm absorbing pigments can be different because of their differing orientation.     

Comparison of magnetite nanocrystal formed by biomineralization and chemosynthesis

Magnetite nanocrystal has been widely used in many fields. Recently, a new magnetite nanocrystal, called magnetosome, has been found in magnetotactic bacteria. In this article, we compared properties of magnetites prepared by co-precipitation with those of magnetosomes isolated from MSR-1 in detail, such as crystalline, morphology, crystal-size distributions, vitro cytotoxicity, and magnetic properties and quantified primary amino groups on the magnetosomes membrane surface by fluorescamine assay for the first time. From the results, it was clear that the magnetosomes might have potential in the biomedical applications in the future.     

Promising Antioxidant and Antimicrobial Potencies of Chemically-Profiled Extract from Withania aristata (Aiton) Pauquy against Clinically-Pathogenic Microbial Strains

Withania aristata (Aiton) Pauquy, a medicinal plant endemic to North African Sahara, is widely employed in traditional herbal pharmacotherapy. In the present study, the chemical composition, antioxidant, antibacterial, and antifungal potencies of extract from the roots of Withania aristata (Aiton) Pauquy (RWA) against drug-resistant microbes were investigated. Briefly, RWA was obtained by maceration with hydro-ethanol and its compounds were identified by use of high-performance liquid chromatography (HPLC). The antioxidant activity of RWA was determined by use of ferric-reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and total antioxidant capacity (TAC). The evaluation of the antimicrobial potential of RWA was performed against drug-resistant pathogenic microbial strains of clinical importance by use of the disc diffusion agar and microdilution assays. Seven compounds were identified in RWA according to HPLC analysis, including cichoric acid, caffeic acid, apigenin, epicatechin, luteolin, quercetin, and p-catechic acid. RWA had excellent antioxidant potency with calculated values of 14.0 ± 0.8 µg/mL (DPPH), 0.37 ± 0.08 mg/mL (FRAP), 760 ± 10 mg AAE/g (TAC), and 81.4% (β-carotene). RWA demonstrated good antibacterial potential against both Gram-negative and Gram-positive bacteria, with inhibition zone diameters ranging from 15.24 ± 1.31 to 19.51 ± 0.74 mm, while all antibiotics used as drug references were infective, except for Oxacillin against S. aureus. Results of the minimum inhibitory concentration (MIC) assay against bacteria showed that RWA had MIC values ranging from 2.13 to 4.83 mg/mL compared to drug references, which had values ranging from 0.031 ± 0.003 to 0.064 ± 0.009 mg/mL. Similarly, respectable antifungal potency was recorded against the fungal strains with inhibition zone diameters ranging from 25.65 ± 1.14 to 29.00 ± 1.51 mm compared to Fluconazole, used as a drug reference, which had values ranging from 31.69 ± 1.92 to 37.74 ± 1.34 mg/mL. Results of MIC assays against fungi showed that RWA had MIC values ranging from 2.84 ± 0.61 to 5.71 ± 0.54 mg/mL compared to drug references, which had values ranging from 2.52 ± 0.03 to 3.21 ± 0.04 mg/mL. According to these outcomes, RWA is considered a promising source of chemical compounds with potent biological properties that can be beneficial as natural antioxidants and formulate a valuable weapon in the fight against a broad spectrum of pathogenic microbes.     

Natural Products Produced in Culture by Biosynthetically Talented Salinispora arenicola Strains Isolated from Northeastern and South Pacific Marine Sediments

Laboratory cultures of two ‘biosynthetically talented’ bacterial strains harvested from tropical and temperate Pacific Ocean sediment habitats were examined for the production of new natural products. Cultures of the tropical Salinispora arenicola strain RJA3005, harvested from a PNG marine sediment, produced salinorcinol (3) and salinacetamide (4), which had previously been reported as products of engineered and mutated strains of Amycolatopsis mediterranei, but had not been found before as natural products. An S. arenicola strain RJA4486, harvested from marine sediment collected in the temperate ocean waters off British Columbia, produced the new aminoquinone polyketide salinisporamine (5). Natural products 3, 4, and 5 are putative shunt products of the widely distributed rifamycin biosynthetic pathway.     

A simple method to estimate the magnetic moment of magnetic micro-particles

Micro-particles in suspension in a fluid are an example of a very low Reynolds number problem. In this case, no inertial effects are observed. Magnetic micro-particles with magnetic moment m, suspended in a fluid orient to applied external magnetic fields B due to the interaction between the field and the magnetic moment. In this work, we present a simple method to estimate the total magnetic moment of magnetic micro-organisms. The method is based on the application of an external oscillating magnetic field in the sites where the micro-organisms are. In this case, it is possible to obtain theoretically the solution of the equation of motion (rotation of the organism and its trajectory). The solution is a transcendental equation relating the orientation angle and m and can be solved by numerical methods. Changing the frequency and/or the field intensity, it is possible to obtain a situation in which the crystal rotates uninterruptedly (a resonance regime). This condition is related to the applied field intensity, to the frequency, to the medium viscosity, to the crystal dimension, and to the micro-crystal magnetic moment m. The method can be used to estimate the total cellular magnetic moment of magnetic micro-particles.     

The natural and synthetic indole weaponry against bacteria

The emergence of drug resistant bacterial infections leading to high mortality rates has posed a formidable challenge to organic synthesis and medicinal chemists to deliver potent and novel antibacterial drug candidates. In particular, antibacterial agents based on novel chemotypes and first-in-class drug candidates with novel mode of actions are highly desired. Indole scaffold has found a consistent presence in the bioactive molecules of synthetic and natural origin. The potential of indole based small molecules as antibacterial agents has not been as much explored as in other areas of medicine, like cancer therapy. In this review, we present a brief account of indole based antibacterial small molecules which have been either synthesized in the laboratory or isolated from natural sources and provide intriguing potential leads in the antibiotic drug discovery research.     

The Effect of Fermentation with Kefir Grains on the Physicochemical and Antioxidant Properties of Beverages from Blue Lupin (Lupinus angustifolius L.) Seeds

Plant derived fermented beverages have recently gained consumers’ interest, particularly due to their intrinsic functional properties and presence of beneficial microorganisms. Three variants containing 5%, 10%, and 15% (w/w) of sweet blue lupin (Lupinus angustifolius L. cv. “Boregine”) seeds were inoculated with kefir grains and incubated at 25 °C for 24 h. After processing, beverages were stored in refrigerated conditions (6 °C) for 21 days. Changes in microbial population, pH, bioactive compounds (polyphenolics, flavonoids, ascorbic acid), reducing sugars, and free amino acids were estimated. Additionally, viscosity, firmness, color, and free radicals scavenging properties were determined. Results showed that lactic acid bacteria as well as yeast were capable of growing well in the lupin matrix without any supplementation. During the process of refrigeration, the viability of the microorganisms was over the recommended minimum level for kefir products. Hydrolysis of polysaccharides as well as increase of free amino acids was observed. As a result of fermentation, the beverages showed excellent DPPH, ABTS^+·, ^·OH, and O₂⁻ radicals scavenging activities with a potential when considering diseases associated with oxidative stress. This beverages could be used as a new, non-dairy vehicle for beneficial microflora consumption, especially by vegans and lactose-intolerant consumers.     

Autonomously Sensing Hydrogels for the Rapid and Selective Detection of Pathogenic Bacteria

The development of a versatile approach for the rapid and sensitive detection of relevant pathogenic bacteria and autonomous signaling of the detection events in reporter hydrogel film coatings is reported. Exploiting chitosan hydrogel films equipped with chromogenic or fluorogenic reporter moieties, the presence of the Gram‐negative bacterium Pseudomonas aeruginosa and the Gram‐positive bacterium Staphylococcus aureus is sensed within 1 h by detecting the characteristic enzymes α‐glucosidase and elastase with limits of detection (LOD) <45 × 10⁻⁹m and <20 × 10⁻⁹m , respectively, for this observation time. The values for the LOD are two to three orders of magnitude smaller than the concentrations of the enzymes detected in the corresponding bacterial supernatants. The results show that the covalently conjugated reporter moieties are exclusively and efficiently reacted by the associated enzyme, allowing in principle for discrimination among different types of bacteria. Since high enzyme concentrations are a result of proliferating bacteria, e.g., in wounds or food, and since the selectivity of the reporting function is easily adapted to bacteria of choice, these reporter hydrogels comprise an interesting platform for the rapid detection of bacteria.