Robert Armon

Cinnamon extracts’ inhibitory effect on Helicobacter pylori

Ethanol and methylene chloride extracts of cinnamon were compared for their effect on Helicobacter pylori growth and urease activity. Methylene chloride extract was found to inhibit growth of H. pylori, while ethanol extract counteracted its urease activity. Cinnamon extract (from methylene chloride) inhibited H. pylori at concentration range of common antibiotics. Complete inhibition in vitro was achieved by 50 microg/ml in solid medium (egg yolk emulsion agar) and by 15 microg/ml in liquid medium (supplemented brain heart infusion broth). The cinnamon extracts were more inhibitory on free urease than on whole cell urease.

Pitting corrosion of carbon steel caused by iron bacteria

Abstract Corrosion mechanism of 1020 AISI carbon steel was studied in iron bacteria contaminated water. A mixed culture of iron oxidizing bacteria, originally isolated from rust deposits of a clogged carbon steel heat exchanger was used. Weight loss and electrochemical measurements were carried out in 1 g l−1 NaCl solution with or without the addition of iron bacteria culture. The experimental results show that addition of the iron bacteria culture to 1 g l−1 NaCl solution induces a drastic ennoblement of corrosion potential (Ecorr) from −0.75 to −0.25 V (SCE) and surface passivation. Through further exposure, Ecorr slowly shifted back and the steel underwent a severe pitting attack, an effect which was not observed with 1 g l−1 NaCl solution alone or when augmented with a nutrient medium. Electrochemical measurements show that the experimentally observed strong acceleration in pitting corrosion process occurred due to an increase in both cathodic and anodic reaction rates, induced by the iron bacteria.

Microbial degradation of aromatic and polyaromatic toxic compounds adsorbed on powdered activated carbon

Abstract The microbial degradation of phenol (300–1300 mg l −1 ), p -nitrophenol (50–500 mg l −1 ), and phenanthrene (50–300 mg l −1 ) adsorbed on powdered activated carbon (PAC) was studied. The combination of physical sorption and biological degradation on PAC, which serves as adsorbent carrier, was compared with the degradation performance of suspended cells and cultures attached to sand, which serves as an example of an inert support. Almost similar profiles of degradation were obtained in the cultures with PAC for the three compounds studied, over the entire concentration range. However, at the higher concentrations, degradation was dramatically inhibited, or even ceased completely, in suspended or sand-attached cultures, even though specialized mixed bacterial cultures adapted to high toxicant concentrations were used in each case. Degradation with PAC assumes an intrinsic relationship between the activated carbon and bacteria in the same environment, thus regenerating the surface of the adsorbent/ carrier as diffusion and degradation proceed. The adsorbed material desorbs, diffuses out of the carbon and can then be metabolized. Our results highlight the applicability of activated carbon, in either powdered or granular form, to achieve a steady-state operation in continuous process, for the treatment of toxic chemicals, even with specialized bacteria.

Whole Cell Imprinting in Sol-Gel Thin Films for Bacterial Recognition in Liquids: Macromolecular Fingerprinting

Thin films of organically modified silica (ORMOSILS) produced by a sol-gel method were imprinted with whole cells of a variety of microorganisms in order to develop an easy and specific probe to concentrate and specifically identify these microorganisms in liquids (e.g., water). Microorganisms with various morphology and outer surface components were imprinted into thin sol-gel films. Adsorption of target microorganism onto imprinted films was facilitated by these macromolecular fingerprints as revealed by various microscopical examinations (SEM, AFM, HSEM and CLSM). The imprinted films showed high selectivity toward each of test microorganisms with high adsorption affinity making them excellent candidates for rapid detection of microorganisms from liquids.

Bacteriophages as indicators of pollution

Abstract Water pollution is an undesired reality encountered in many countries. To prevent major outbreaks of infectious disease caused by pathogenic microorganisms such as viruses, bacteria, and protozoa that contaminate the water, the scientific community has searched for various indicators that could be used to alert their presence. Among the possible indicators, bacteriophages are receiving increasing attention because of the concern with waterborne viral diseases. This review summarizes the advantages and disadvantages of utilizing bacteriophages as pollution indicators as seen from the somewhat confusing information accumulated from almost 50 years of research and proposes some new directions in the application of bacteriophages as indicators. Bacteriophages have been studied worldwide as pollution indicators because of the ease of their detection and their morphological similarity to human viruses. In addition, detection of human viruses is still a highly skilled and costly process. Generally speak...

Effect of suspended solids on wastewater disinfection efficiency by chlorine dioxide

Abstract Effluents enriched with high suspended solids concentration were tested for disinfection with chlorine dioxide. Following disinfection with various chlorine dioxide concentrations from 0 mg/l to 52.78 mg/l and contact times from 2 up to 24 h, half of the experimental samples were crushed (by Ultra-Turax) and tested for survival of indicator microorganisms. The crushing process revealed that a certain fraction of indicator microorganisms were left intact as a result of chlorine dioxide disinfection. This fraction was found to be able to regrow as was shown for all bacterial indicators, such as coliforms, fecal coliforms, enterococci and heterotrophic count, despite high disinfectant concentrations. The study results indicate that some microorganisms fraction entrapped into suspended flocs can survive disinfection with chlorine dioxide, depending also on indicator type, therefore their prior removal by coagulation, sedimentation and filtration is a major prerequisite for successful disinfection.

Virus removal by drinking water treatment processes

Viruses are very small microorganisms that are parasites of human, animals, bacteria, and plants. In water, the only viruses that can be a health risk for man or animals are the enteric viruses: viruses that are excreted in feces by infected individuals. Some of these viruses are extremely resistant in the aquatic environment and can be found in relatively low numbers in most waters contaminated by fecal material. However, because as little as one to ten infectious viruses are sufficient to infect a susceptible individual, it is important to eliminate even minute numbers of these microorganisms from drinking water. Methods have been developed for the detection of viruses in volumes of water exceeding 10001. With the increase in sensitivity and the wider use of methods for their detection in drinking water, viruses have been detected in drinking water meeting current standards of water quality. This paper reviews the literature on these occurrences.

Eichhornia crassipes capability to remove naphthalene from wastewater in the absence of bacteria

The aim of the current study was to investigate the potential of an aquatic plant, the water hyacinth (Eichhornia crassipes) devoid rhizospheric bacteria, to reduce naphthalene (a polyaromatic hydrocarbon) present in wastewater and wetlands. The capability of sterile water hyacinth plants to remove naphthalene from water and wastewater was studied in batch systems. Water hyacinths enhance the removal of pollutants through their consumption as nutrients and also through microbial activity of their rhizospheric bacteria. Experimental kinetics of naphthalene removal by water hyacinth coupled with natural rhizospheric bacteria was 100% after 9 d. Plants, decoupled of rhizospheric bacteria, reduced naphthalene concentration up to 45% during 7 d. Additionally, naphthalene uptake by water hyacinth revealed a biphasic behavior: a rapid first phase completed after 2.5 h, and a second, considerably slower rate, phase (2.5-225 h). In conclusion, water hyacinth devoid rhizospheric bacteria reduced significantly naphthalene concentration in water, revealing a considerable plant contribution in the biodegradation process of this pollutant.

Efficiency of phenol biodegradation by planktonic Pseudomonas pseudoalcaligenes (a constructed wetland isolate) vs. root and gravel biofilm.

In the last two decades, constructed wetland systems gained increasing interest in wastewater treatment and as such have been intensively studied around the world. While most of the studies showed excellent removal of various pollutants, the exact contribution, in kinetic terms, of its particular components (such as: root, gravel and water) combined with bacteria is almost nonexistent. In the present study, a phenol degrader bacterium identified as Pseudomonas pseudoalcaligenes was isolated from a constructed wetland, and used in an experimental set-up containing: plants and gravel. Phenol removal rate by planktonic and biofilm bacteria (on sterile Zea mays roots and gravel surfaces) was studied. Specific phenol removal rates revealed significant advantage of planktonic cells (1.04 × 10(-9) mg phenol/CFU/h) compared to root and gravel biofilms: 4.59 × 10(-11)-2.04 × 10(-10) and 8.04 × 10(-11)-4.39 × 10(-10) (mg phenol/CFU/h), respectively. In batch cultures, phenol biodegradation kinetic parameters were determined by biomass growth rates and phenol removal as a function of time. Based on Haldane equation, kinetic constants such as μ(max) = 1.15/h, K(s) = 35.4 mg/L and K(i) = 198.6 mg/L fit well phenol removal by P. pseudoalcaligenes. Although P. pseudoalcaligenes planktonic cells showed the highest phenol removal rate, in constructed wetland systems and especially in those with sub-surface flow, it is expected that surface associated microorganisms (biofilms) will provide a much higher contribution in phenol and other organics removal, due to greater bacterial biomass. Factors affecting the performance of planktonic vs. biofilm bacteria in sub-surface flow constructed wetlands are further discussed.

Diverse effects of ascorbic acid and palmitoyl ascorbate on Helicobacter pylori survival and growth

Among many antioxidants used in the food, pharmaceutical and cosmetic industries, ascorbic acid (AA) is one of the most important. AA has been suggested to decrease the risk of gastric disease (gastritis, duodenal ulcer, and carcinoma) by direct action on Helicobacter pylori. However, there are limited studies on the possible role of AA and its derivatives such as palmitoyl ascorbate (PA) on the growth and survival of H. pylori. In the present study it was demonstrated in vitro that AA in the concentration range 10-20 mg x ml(-1) (50-100 mM) inhibited H. pylori growth in liquid medium under microaerophilic conditions. In contrast, under aerobic conditions AA in the concentration range 2-20 mg x ml(-1) (10-100 mM) significantly increased the survival of H. pylori presumably eliminating the toxic effect of reactive oxygen species on bacterial cells. The hydrophobic derivative of AA, PA (a food antioxidant), demonstrated a strong antibacterial effect, under both aerobic and microaerophilic conditions in the concentration range 0.04-0.4 mg x ml(-1) (0.1-1.0 mM). This effect was also tested on other bacterial strains: Escherichia coli, Proteus vulgaris, Proteus mirabilis, Pseudomonas aeruginosa, Enterococcus faecalis, Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Clostridium sporogenes and Campylobacter jejuni. Among these bacterial strains, PA showed a similar inhibitory effect on B. cereus and B. subtilis as observed with H. pylori. The results suggest that PA may be considered an important AA derivative in eradication of H. pylori in vitro and in vivo and to decrease the risk for gastric diseases.