Effect of combined heat and radiation on microbial destruction.

A series of experiments at several levels of relative humidity and radiation dose rates was carried out using spores of Bacillus subtilis var. niger to evaluate the effect of heat alone, radiation alone, and a combination of heat and radiation. Combined heat and radiation treatment of microorganisms yields a destruction rate greater than the additive rates of the independence agents. The synergistic mechanism shows a proportional dependency on radiation dose rate an Arrhenius dependency on temperature, and a dependency on relative humidity. Maximum synergism occurs under conditions where heat and radiation individually destroy microorganisms at approximately equal rates. Larger synergistic advantage is possible at low relative humidities rather than at high relative humidities.     

Effect of combined heat and radiation on microbial destruction.

A series of experiments at several levels of relative humidity and radiation dose rates was carried out using spores of Bacillus subtilis var. niger to evaluate the effect of heat alone, radiation alone, and a combination of heat and radiation. Combined heat and radiation treatment of microorganisms yields a destruction rate greater than the additive rates of the independence agents. The synergistic mechanism shows a proportional dependency on radiation dose rate an Arrhenius dependency on temperature, and a dependency on relative humidity. Maximum synergism occurs under conditions where heat and radiation individually destroy microorganisms at approximately equal rates. Larger synergistic advantage is possible at low relative humidities rather than at high relative humidities.     

Effect of microbial heat shock proteins on airway inflammation and hyperresponsiveness

Microbial heat shock proteins (hsp) have been associated with the generation and induction of Th1-type immune responses. We tested the effects of treatment with five different microbial hsp (Mycobacterium leprae, Streptococcus pneumoniae, Helicobacter pylori, bacillus Calmette-Guérin, and Mycobacterium tuberculosis) in a murine model of allergic airway inflammation and airway hyperresponsiveness (AHR). Mice were sensitized to OVA by i.p. injection and then challenged by OVA inhalation. Hsp were administered to each group by i.p. injection before sensitization and challenge. Sensitized and challenged mice developed increased serum levels of OVA-specific IgE with significant airway eosinophilia and heightened responsiveness to methacholine when compared with nonsensitized animals. Administration of M. leprae hsp prevented both development of AHR as well as bronchoalveolar lavage fluid eosinophilia in a dose-dependent manner. Treatment with M. leprae hsp also resulted in suppression of IL-4 and IL-5 production in bronchoalveolar lavage fluid, while IL-10 and IFN-gamma production were increased. Furthermore, M. leprae hsp treatment significantly suppressed OVA-specific IgE production and goblet cell hyperplasia/mucin hyperproduction. In contrast, treatment with the other hsp failed to prevent changes in airway responsiveness, lung eosinophilia, or cytokine production. Depletion of gamma/delta T lymphocytes before sensitization and challenge abolished the effect of M. leprae hsp treatment on AHR. These results indicate selective and distinctive properties among the hsp, and that M. leprae hsp may have a potential therapeutic role in the treatment of allergic airway inflammation and altered airway function.     

Solar heat load on man

Different methods have been compared for the estimation of solar heat load on man. The comparison comprised several methods based on the calculation of absorbed solar radiation and one method for calculation of mean radiant temperature (Mrt). Regression analysis was carried out for predicted values and values calculated for a vertical cylinder, assumed as an analog model of a standing man. Regression of mean skin temperature, measured in 10 subjects exposed to solar radiation under a variety of climatic conditions, on predicted radiant heat load was also analysed. Mean skin temperature correlated best withMrt, accounting for more than 50% of the variance. The results indicated that three methods provide a realistic estimation of the radiation heat load, whereas some methods show deviations of several hundred per cent.     

Effect of gamma irradiation on microbial load,aflatoxins and phytochemicals present in Trigonella foenum-graecum

The effects of gamma irradiation on microbial load, total aflatoxins and phytoconstituents content of Trigonella foenum-graecum have been studied. Gamma irradiation at a dose of 2.5 kGy resulted in 2 log reduction of the total aerobic microbial count. A complete sterilization was, however, observed at 10 kGy. The total aflatoxin level decreased gradually with increase in gamma irradiation dose as compared to its un-irradiated counterparts, whereas the high performance liquid chromatography (HPLC) profile showed no change in the levels of phytochemicals up to the gamma irradiation dose of 10 kGy. HPLC profiles, however, differed in peak areas, and retention times of the components. These results suggest that gamma irradiation at a dose of 5.0 kGy was very effective for microbial decontamination because it did not adversely affect the active components of T. foenum-graecum.     

Effect of gamma irradiation on microbial load and sensory characteristics of aniseed (Pimpinella anisum)

Seeds of anise (Pimpinella anisum) were exposed to doses of 0, 5, 10, 15 and 20kGy in a (60)Co package irradiator. Irradiated and unirradiated samples were stored at room temperature. Microbial populations on seeds, total and inorganic soluble solids in water extract and sensory properties of the latter were evaluated after 0, 6 and 12 months of storage. Results indicated that gamma irradiation reduced the aerobic plate counts of aniseed. Immediately after irradiation, the total soluble solids in an extract of irradiated seeds were greater than those of unirradiated ones. The total soluble solids in an extract of irradiated and un-irradiated seeds increased after 6 and 12 months of storage. There were no significant differences (p>0.05) in inorganic soluble solids between the water extract of irradiated and unirradiated aniseeds. Sensory evaluation indicated that gamma irradiation improved sensory characteristics of aniseed water extract tested immediately after irradiation; however, after 12 months of storage, no significant differences (p>0.05) were found in color, taste or flavor between extract of irradiated and unirradiated seeds.     

Effect of the applied organic load rate on biodegradable polymer production by mixed microbial cultures in a sequencing batch reactor

This article studies the operation of a new process for the production of biopolymers (polyhydroxyalkanoates, PHAs) at different applied organic load rates (OLRs). The process is based on the aerobic enrichment of activated sludge to obtain mixed cultures able to store PHAs at high rates and yields. A mixture of acetic, lactic, and propionic acids at different concentrations (in the range 8.5-31.25 gCOD/L) was fed every 2 h in a sequencing batch reactor (SBR). The resulting applied OLR was in the range 8.5-31.25 gCOD/L/day. Even though, as expected, the increase in the OLR caused an increase in biomass concentration (up to about 8.7 g COD/L), it also caused a relevant decrease of maximal polymer production rate. This decrease in polymer production rate was related to the different extent of "feast and famine" conditions, as function of the applied OLR and of the start-up conditions. As a consequence the best performance of the process was obtained at an intermediate OLR (20 gCOD/L/day) where both biomass productivity and PHA storage were high enough. However, at this high OLR the process was unstable and sudden decrease of performance was also observed. The sludge characterized by the highest PHA storage response was investigated by 16S rDNA clone library. The clone library contained sequences mostly from PHA producers (e.g., Alcaligenes and Comamonas genera); however many genera and among them, one of the dominant (Thauera), were never described before in relation to PHA storage response.     

Efficacy of antimicrobial filter treatments on microbial colonization of air panel filters

AIMS: To assess the activity of biostatic agents on the microbial colonization of panel filters. METHODS AND RESULTS: Microfibre glass acrylic filters, both used and unused, were examined for the presence of microorganisms. Test strains were used to verify microbial colonization of filter media. Antimicrobial agents were applied to the filter media and tested for their ability to reduce microbial colonization. The integrity of the panel filters and the antimicrobial activity trends of the filter media treated with antimicrobials were verified. A filtration efficiency test was carried out on the treated filters to evaluate filtration performance. Filters treated with antimicrobials demonstrated markedly less microbial colonization (density and varieties of species), higher filtration efficiency and delayed deterioration of the filter. CONCLUSIONS: The most important results of this study are the demonstration of preservation of the integrity of the filters and the lower release of microorganisms from treated filters. SIGNIFICANCE AND IMPACT OF THE STUDY: These results contribute to the resolution of problems concerning the microbial contamination of panel filters in the heating, ventilating and air-conditioning systems commonly used in the electronic industry, pharmaceutical industry, hospitals and other environments where the absence of contaminating particles and microorganisms is required.     

A field test of commercial soil microbial treatments on native grassland restoration

Seedling establishment and performance are often limiting steps in many grassland restorations. The soil microbial community is thought to be a factor that contributes to the poor performance of seedlings. Therefore, we conducted a field test to examine the ability of four treatments to alter the soil microbial community and improve seedling performance during restoration. Treatments were commercially available bacterial inoculum, fungal inoculum, fungicide, and a bacteria/fungicide combination which were all designed and sold to enhance plant performance. We hypothesized that if the soil microbial community was limiting the performance of seedlings, then these products would remediate detrimental effects of the soil microbial community resulting in greater seedling performance. However, during the 2 years after restoration, no effect of the treatments was found. It is plausible that the treatments designed for agriculture or home garden settings were not appropriate for a wildland system.     

Degradation of meta-trifluoromethylbenzoate by sequential microbial and photochemical treatments

Abstract m - and p -trifluoromethyl (TFM)-benzoates are completely degraded by aerobic bacteria that catabolize alkylbenzoates; biodegradation ceases after ring-fission with the accumulation of a trifluoromethyl muconate semialdehyde (2-hydroxy-6-oxo-7,7,7-trifluorohepta-2,4-dienoate, TFHOD) which is resistant to biochemical attack. A bacterium (Strain V-1), isolated from sea-water, grew aerobically on benzoate or m -toluate. Cells grown on benzoate or m -toluate oxidized both compounds at similar relative rates. Catabolism involved benzoate 1,2-dioxygenase (decarboxylating) and meta -cleavage to yield muconate semialdehydes. Cells grown on benzoate metabolized m -TFM-benzoate to TFHOD. The ring-fission products from m -toluate and TFHOD were degraded by sunlight, and equimolar fluoride was released from TFHOD. Sequential biochemical and photochemical treatment allowed the destruction of m -TFM-benzoate beyond the biochemically recalcitrant intermediate TFHOD.     

Effects of heat and high-pressure treatments on antigenicity of beef extract

The sera of bovine gamma globulin (BGG) positive beef allergic patients were used in this study in order to investigate changes in IgE-specific binding activity with regard to beef extract altered by heat or high-pressure treatment. In inhibition-ELISA, the sample treated at 60 degrees C did not show any significant changes in the antigenicity of BGG, but the sample treated at 100 degrees C showed a decrease of the antigenicity. In the case of the treatment with heating at 100 degrees C, heat-coagulation occurred in the beef extract. The resulting supernatant and precipitate of the sample by centrifugation were analyzed by immunoblotting. Only the fraction of precipitate showed a specific binding activity with the sera. Based on this result, it was speculated that the persistent antigenicity found even after the treatment at 100 degrees C in inhibition-ELISA remained principally in the heat-coagulated fraction, which indicated the importance of the method of handling the heat-coagulation in heat treatment. High-pressure treatments (200 MPa-600 MPa) of beef extract did not show any significant changes in the binding with the sera.     

An attempt to improve the flavour of 'nono' by the use of starter cultres

Three close-fitting lid fermenters were incubated at 27 ± 2°C for 120 h. 'A' served as a control and contained 100 ml raw goats' milk; 'B' contained 50 ml 48-h-old nono as starter culture plus 50 ml pasteurized milk; and 'C' contained 100 ml pasteurized milk only. The pH and lactic acid contents were determined at intervals. Fermenter 'B' gave the best results in that the milk reached the lowest pH values and the highest lactic acid contents, and this resulted in a more appetizing and bitter product.     

Effect of heat treatments on stability of altemariol, alternariol monomethyl ether and tenuazonic acid in sunflower flour

A study was carried out to evaluate the effect of heat treatment on the stability of alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TeA) in sunflower flour and the effectiveness of this treatment by a biological assay in rats. The concentrations of AOH and AME remained constant during heating at 100°C for up to 90 minutes while TeA concentration decreased with time to 50% after 90 minutes. The most effective treatment in reducing AOH and AME levels was heating at 121°C for 60 minutes. Histopathological evaluation in the biological assay in rats fed withAlternaria toxins showed marked atrophy and fusion of villi in the intestines and liver cell damage; these lesions were less severe in rats fed heat-treated sunflower flour in line with the reduced toxin content. However, a lower weight gain and a noticeable renal damage in rats were produced when they fed decontaminated flour.     

Removal of microbial multi-species biofilms from the paper industry by enzymatic treatments

This study aimed to characterize biofilms from the paper industry and evaluate the effectiveness of enzymatic treatments in reducing them. The extracellular polymeric substances (EPS) extracted from six industrial biofilms were studied. EPS were mainly proteins, the protein to polysaccharide ratio ranging from 1.3 to 8.6 depending on where the sampling point was situated in the paper making process. Eight hydrolytic enzymes were screened on a 24-h multi-species biofilm. The enzymes were tested at various concentrations and contact durations. Glycosidases and lipases were inefficient or only slightly efficient for biofilm reduction, while proteases were more efficient: after treatment for 24 h with pepsin, Alcalase® or Savinase®, the removal exceeded 80%. Savinase® appeared to be the most adequate for industrial conditions and was tested on an industrial biofilm sample. This enzyme led to a significant release of proteins from the EPS matrix, indicating its potential efficiency on an industrial scale.     

Removal of microbial multi-species biofilms from the paper industry by enzymatic treatments

This study aimed to characterize biofilms from the paper industry and evaluate the effectiveness of enzymatic treatments in reducing them. The extracellular polymeric substances (EPS) extracted from six industrial biofilms were studied. EPS were mainly proteins, the protein to polysaccharide ratio ranging from 1.3 to 8.6 depending on where the sampling point was situated in the paper making process. Eight hydrolytic enzymes were screened on a 24-h multi-species biofilm. The enzymes were tested at various concentrations and contact durations. Glycosidases and lipases were inefficient or only slightly efficient for biofilm reduction, while proteases were more efficient: after treatment for 24 h with pepsin, Alcalase? or Savinase?, the removal exceeded 80%. Savinase? appeared to be the most adequate for industrial conditions and was tested on an industrial biofilm sample. This enzyme led to a significant release of proteins from the EPS matrix, indicating its potential efficiency on an industrial scale.     

Effect of heat and acid decontamination treatments on the recovery of Legionella pneumophila from drinking water using two selective media.

Two different decontamination systems, heat and acid, and two isolation media, GVPC and MWY agar were tested for the recovery of Legionella pneumophila from drinking water. The samples were concentrated by filtration through 0.2 micron polyamide filter and the membranes were resuspended in the original water samples. The suspension was divided into three parts: the first was placed in a 50 degrees C water bath, the second was acidified in HCl-KCl solution and the third did not undergo any treatment. The isolation was made by means of media containing charcoal, yeast extract and glycine with cycloeximide (GVPC) or vancomycin, polimixin B, anysomicin and dyes (MWY). Heating at 50 degrees C for 30 minutes was seen to be the best decontamination system above all when used with GVPC agar. Moreover, with this pretreatment higher counts were obtained both on MWY and GVPC agar. The MWY agar produced the highest isolatin percentages and the highest counts.     

Heat and microbial treatments for nutritional upgrading of wheat straw

The ligninolytic activities of four cellulolytic organisms were compared using straw. Only Aspergillus japonicus and Polyporous versicolor appreciably degraded lignin with A. japonicus yielding the most protein. In solid culture, most protein was produced by P. versicolor, closely followed by A. japonicus. Pretreatment of the straw by hot water facilitated biodegradation and protein production. The nutritional value of the residual straw was also increased by some fungal cultures. The greatest amount of degradable polysaccharide in the straw was made available by A. japonicus in liquid media and Pleurotus ostreatus in solid media.     

Effect of polyvinylpyrrolidone on microbial cells

The oral administration of polyvinylpyrrolidone to rats produces no effect on the intestinal microflora. At the same time, polyvinylpyrrolidone solutions decrease the toxicity of Escherichia coli and Proteus vulgaris, produce a bactericidal and agglutinating effect.