Liposomes enhance bioremediation of oil-contaminated soil.

Liposomes (composed of soy phosphatides) in the form of small unilamellar vesicles (SUV), when added to soil contaminated by crude oil, accelerate bioremediation. After three weeks incubation at 30 degrees C, using soil experimentally contaminated (with 10,000 ppm crude oil), level of bioremediation increased from 40% without SUV to 75% with SUV (0.1 wt% phospholipids per dry weight soil). Similarly, for accidentally contaminated soil (with approximately 17,000 ppm crude oil), addition of 0.1 wt% SUV to the soil increased the bioremediation level from 55 to 80%. The enhancing effect of liposomes is explained by two interrelated phenomena: a large increase both in total bacteria number and in diversity of bacterial species in the soil. Comparison after four weeks revealed 21 bacterial species in the presence of liposomes (many being oil-degrading bacterial species) and only nine species in the absence of liposomes. Both effects may be related to the physical effects of liposome phospholipids, which modify the crude oil by wetting it, thereby making it more accessible to the microorganisms. In addition, liposome phospholipids serve as phosphate and nitrogen sources for the bacteria.

Antigenicity of Mycobacterium paratuberculosis superoxide dismutase in mice.

Mycobacterium paratuberculosis (MPT) is the etiologic agent of paratuberculosis. The disease is prevalent in cattle worldwide, and exacts a heavy financial toll. Effective control requires the development of acellular vaccines offering a better protection than the current available vaccines without side effects and allowing the discrimination between infected and vaccinated animals. We studied the immune response of mice to the MPT superoxide dismutase (SOD) alone or adjuvanted by Ribi. We cloned, overexpressed and purified this antigen in Escherichia coli. Spleen cells from immunized mice, after exposure to recombinant MPT SOD (MPT rSOD), produced significant levels of IFNgamma, TNFalpha and IL-6. IFNgamma and TNFalpha production was increased by the addition of Ribi. In contrast, low levels of NO, IL-4 and IL-10 were secreted by spleen cells culture from immunized mice. The immunoglobulin isotype distribution analysis showed that Ribi adjuvant clearly induced a significantly higher anti-MPT rSOD antibody production of all classes tested and decreased the IgG1/IgG2a ratio thus improving the Th1 response. Delayed-type hypersensitivity responses in mice footpads were observed only in mice immunized with MPT rSOD emulsified in Ribi. Vaccination of MPT rSOD emulsified with Ribi induced both a Th2 and Th1 type of immune response with the later slightly more pronounced. The results presented here on the immunogenicity of MPT SOD suggest that this antigen should be further tested as a candidate antigen for a future acellular vaccine against paratuberculosis.