Natural biodegradation of heavy oil in the marine environment can be accelerated by the addition of nutrients or seeding of pre-selected microorganisms. In this study, a microcosm experiment was conducted to investigate the effects of inorganic nutrient supplementation (biostimulation) and bacterial consortium amendment (bioaugmentation) on the natural degradative processes of artificially contaminated sediment. Our results revealed that the addition of nutrients had greater effect on remediation than the addition of bacterial cells. Supplementation of inorganic nutrients promoted and sustained the growth of oil-degrading and heterotrophic bacteria throughout the experimental period. Highest reduction in the total petroleum hydrocarbons, and of their components, n-alkanes, polycylic aromatic hydrocarbons (PAHs) and alkyl PAHs, were obtained in the biostimulated microcosms. Changes in the bacterial community were monitored by the PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) method targeting the 16S rDNA gene. Results revealed different responses of the bacterial community to the addition of heavy oil and remediation agents. Shifts in the bacterial communities in the seawater were more dynamic than in the sediment. Results of this study showed that addition of remediation agents significantly enhanced the natural biodegradation of heavy oil in a sediment-seawater microcosm trial.
The supercooling-facilitating (SCF) activities, that is, the anti-ice nucleation activity of the hot water extracts from five types of processed food refuse was examined. The extract with the highest activity among five hot water extracts was coffee refuse, showing 1.50℃ of SCF activity at a final concentration of 0.1 mg/ml. From the hot water extract of coffee refuse, the coffee refuse extract containing various polyphenols was prepared by the ultrafiltration (less than MWCO 10,000), a solvent fractionation of ethyl acetate. The yield of coffee refuse extract was 0.9% (w/w) from dried coffee refuse. The SCF activity of the coffee refuse extract at a final concentration of 1.0 mg/ml was 4.2℃. HPLC analysis of the coffee refuse extract showed that caffeine and chlorogenic acid, which are major components of coffee, could be found at 173 and 62.3 µg/ml, respectively. However, the SCF activities of both compounds (0.70 and 1.06℃) at a final concentration of 0.1 mg/ml were lower than those of ferulic acid and coumaric acid, respectively at 3.40 and 2.35℃. This is the first report to our knowledge on the SCF activity of caffeine. The SCF activity of caffeine at a final concentration of 1.0 mg/ml was 2.3℃. The specificity of caffeine against various ice nuclei containing calcium oxalate, 9-fluorenon, and ice nucleating bacteria was examined. Caffeine at a final concentration of 1.0 mg/ml could inhibit the ice nucleation activity of calcium oxalate, and Pseudomonas fluorescens KUIN-1 at the same level that of as silver iodide. From these results, it was suggested that the extract could be able to be applied to the field to control the frost damage of the vegetables and that the harvested vegetables might be stored unfrozen even at 0℃ or less.
The aim was to isolate Campylobacter jejuni-specific lytic phages from meats on the market in Japan. These phages were effectively isolated from 13 of 15 (86.7%) retail chicken meat samples (skin and liver) by the enrichment method using Preston Campylobacter Selective Enrichment Broth and 10 host Campylobacter strains. Among the 26 phage isolates, 14 were extracted by means of C. jejuni L26 as a host strain. Phage PHC10 showed the broadest lytic spectrum: active against 67.4% of the 46 C. jejuni strains tested. The other phage isolates showed different lytic spectra. Because phages PHC5, PHC10, PHC19, PHC22, and PHC25 possess an icosahedral head and a contracted tail, they seem to be members of the Myoviridae family. Effects of 19 phage isolates on viability of C. jejuni were investigated. These phages reduced viable counts of C. jejuni by 1-3 log after 6-12 h of incubation at 42℃ as compared to the initial counts. The C. jejuni L26 was found to be suitable as a host because of the wide hosting range. The phages isolated in this study seem to be promising biocontrol agents against C. jejuni in food.
Hypochlorous acid (HOCl) solution (200 ppm, pH 6) was prepared and evaluated for their stabilities and microbicidal activities. We demonstrated that HOCl is unstable against ultraviolet (UV) light, sunshine, contact with air, and elevated temperature (≧25℃). Furthermore, in the HOCl solution, the presence of excess NH2- or CHO-containing organic compounds such as proteins and carbohydrates, or of inorganic ions such as NO2-, SO3-, PO3-, Fe2+, Cu2+, and CuS, resulted in the rapid consumption of HOCl by oxidation reactions, and significantly decreased the microbicidal activity of the HOCl solution against coliform bacteria and total viable cell count. Thus, production of stable HOCl solution requires formulation in pure water harboring concentrations as low as possible of various compounds and ions, as well as storage in dark and cool conditions (<10℃) to maintain the concentration of HOCl molecules and microbicidal activity.
Linear alkylbenzene sulfonate (LAS) and polyoxyethylene lauryl ether (POLE) are major surfactants contained in the laundry detergents. In the present study, the antibacterial activities of the surfactants to aquatic microorganisms were compared. When freshwater samples from a small river in Okayama city were treated with each of the surfactants, only LAS showed the significant antibacterial activity. Several strains, which survived after the treatment with 2.0% LAS, were isolated and identified by sequencing of 16S rDNA. All strains were classified into the family Enterobacteriaceae. However, this family was not a major member of the aquatic microflora, suggesting that the bacteria in Enterobacteriaceae have a common property of LAS-resistance in the river water.
Most of the ice nucleation activity inhibitor reported so far are compounds processing the hydroxyl group such as the polyphenolic derivative. After examining the anti-ice nucleation activity of the purine base, the highest compound is theophylline, and the activity showed 3.80±0.32℃ at a final concentration of 0.1 mg/ml. We found that the activity of the adenine which was essential to genome information DNA was higher than that of guanine. After examining effect of adenine concentration, high activity showed 9.1±1.2℃ and became approximately constant above 0.1 mg/ml. This active rise is a result of effect of concentration under alkaline condition. Therefore after examining effect of pH on the activity of adenine, this activity rose under an alkaline condition. The active rise predicts that an electric charge of adenine is a factor. Among four kinds of nucleotide of 6 bases, poly-A nucleotide was higher and showed 1.33±0.42℃ at a final concentration of 0.1 mg/ml. This activity of poly-A were proportional to the number of the base. From these results, it was suggested that the poly-A and adenine could be able to be applied to the field to preserve the blood and tissue which differentiated in the generative medicine.