VAAM-Jahrestagung 2011 Karlsruhe, 3.–6. April 2011

FMP017Prevalence and pathogenicity of mycobacteria on a farmin Upper Franconia (Bavaria, Germany)O. Kreß*, O. MeyerDepartment of Ecological Microbiology, University of Bayreuth, Bayreuth,GermanyThe increase of allergic and asthma diseases in the industrialized world hasoften been explained using the „Hygiene Hypothesis” which assumes adecline of human contact with microorganisms [1]. Farm environment inchildhood reduces the development of allergies and asthma [2].Mycobacteria, which are most efficient in the stimulation of the immunesystem, were assumed to be responsible for this so called „Farm-Effect” [3].Farm animals and thereby also the quality of food, produced on farms,benefit from this effect as well. According to their growth speed andpigmentation, mycobacteria can be classified into four Runyon-Groups. Themembers of these groups exhibit either weak pathogenic (Group I & II),increased pathogenic (Group III) or non pathogenic (Group IV)mycobacteria [4].In this study we have located the reservoirs of mycobacteria and theirrespective Runyon-Group on a farm in Upper Franconia (Bavaria,Germany). Mycobacteria were isolated from several farm sites and assignedaccording to the Runyon-classification.We were able to identify mycobacteria of all four Runyon-Groups in openland habitats (soil, manure, and dunghill). Their number was between 5,760and 18,200 cfu per gram dry weight. Mycobacteria of Runyon-Group IIwere characteristic of old cattle shed (80 to 2,130 cfu per gram dry weight).The corn silage and the new cattle shed revealed no mycobacteria.The data show that various locations on farms are indeed populated bymycobacteria and that weakly pathogenic mycobacteria of the Runyon-Group II in combination with high levels of mycobacteria from all Runyongroupsmay account for the stimulation of the immune system of humansand livestock on farms.FMP018The use of UV-C light to inactivate microorganisms infruit juicesM. Huch*, A. Müller, V. Graef, M. Stahl, C.M.A. FranzInstitute of Safety and Quality of Fruits and Vegetables, Max RubnerInstitute, Karlsruhe, GermanyUV-C light (200-280 nm) can be used for the inactivation ofmicroorganisms, as the absorption maxima of DNA components fall in thisrange (260 nm). This technique has been successfully applied for thedisinfection of drinking water in Germany for many years. UV-C treatmentof more coloured and turbid liquids, such as milk and wine, is also appliedin foreign countries. One limiting factor, however, is the low penetrationdepth of UV-C into liquids such as fruit juices, which are coloured and maycontain particles. To overcome this problem, UV-C technologies which arecurrently used are based on thin films or turbulence flows. In this study, anew technology using Dean vortices was used to compensate the problem oflack of penetration depth. Four different microorganisms, i.e. Lactobacillusplantarum BFE 5092, Escherichia coli DH5α, Alicyclobacillusacidoterrestris DSM 2498 and S. cerevisiae DSM 70478 were investigated.Parameters like optical density, turbidity and viscosity, which influence theinactivation of microorganisms, were evaluated using Ringer`s buffersolution coloured with a dye, or fruit juices such as elderberry nectar, cloudyapple juice or blood orange juice, which differ considerably in opticaldensity and turbidity. The optical density appeared to be the most importantfactor which influenced the bacterial inactivation. Cell counts of L.plantarum BFE 5092 could be reduced in Ringer`s solution adjusted withdye from an initial level of ca. 1x10 8 cfu/ml to 1x10 1 cfu/ml at an opticaldensity of 20 with a dosage of 9.6 kJ/L. However, only a log 1.5 reductioncould be achieved at an optical density of 140 using the same dosage.Furthermore, no noticeable effect on inactivation was determined by varyingthe turbidity or the viscosity. However, an increasing flow rate, and thecorresponding higher Dean Number improved the efficacy of UV-Ctreatment.FMP019Detection and inactivation of Cronobacter species ininfant formulaS. Baumann*, J. Rudat*Technical Biology, Karlsruhe Institute of Technology (KIT), Karlsruhe,GermanyThe novel genus Cronobacter combines five bacterial species formerlyclassified as Enterobacter sakazakii [1]. In the last decades, theseopportunistic pathogens have been implicated in several incidents as thecause of meningitis and enterocolitis with high mortality rates in prematureinfants resulting from feeding with contaminated powdered infant formula(PIF) [2].PIF therefore is strictly recommended to be „sakazakii-free” which isdefined as the absence of any colony forming unit in 30 samples of 10g ofPIF [3]. As Cronobacter is ubiquitous in the environment and can survivefor long periods in dried products and even has been shown to survive spraydrying, the problem of this bacterium in PIF continues to be a majorchallenge to the industry [4].In cooperation with a large scale producer of PIF we are developing amodified production process assuring the inactivation of Cronobacter.Detection of viable cells is accomplished by quantitative RealTime PCR aswell as selective growth on chromogenic media following enrichmentculture.[1] Iversen, C. et al (2008): Int J Syst Evol Microbiol 58 (6),1442.[2] Friedemann M (2008), Bundesgesundheitsbl Gesundheitsforsch Gesundheitsschutz 51, 664.[3] Besse, N.G. et al (2006): J AOAC Int 89, 1309.[4] Arku, B. et al (2008): Int J Dairy Tech 61 (1), 102.FMP020Effect of different protectants on viability ofthermotolerant acetic acid bacterium Acetobactersengalenisis Acetobacter sengalenisisR. Shafiei* 1,2 , P. Thonart 11 Center Wallon de Biologie Industrielle, University of Liège, Liege,Belgium2 Faculty of Science, Department of Microbiology, University of Isfahan,Isfahan, BelgiumProduction of vinegar at high temperature (>37° C) needs special processesand equipments; one of the key elements in the process, is the accessibilityof active and stable starters. In this study the influences of different cryoprotectiveagents on some steps (freezing, drying and storage) of starterproduction were investigated. To achieve this goal, Acetobactersenegalensis, was used as a thermotolerant acetic acid bacterium.Glucose was used as carbon source in fermentor to produce biomass.Different cryo-protectants (manitol (20%), glycerol (3%), sucrose (10%),trehalose (5%), glutamate (3%), maltodextrin (10%), skimmed milk (10%)and spent growth medium) were added to washed and unwashed biomass.The lyophilized cells (92-93% water content) were stored in darkness underdifferent temperatures (-20° C, +4° C and 35° C). The viability of cells afterrehydration, activity of glucose dehydrogenase, gluconate dehydrogenaseand soluble protein contents were determined up to 6 months.According to the results, washing of cells by tap water has no effect onviability of cells during freezing and more than 97% of cells are alive in alltreatments. After lyophilization, unwashed cells showed higher viability inall treatments in comparison to washed cells. On the basis of residual viablecells, manitol, maltodextrin, and spent growth medium showed the highestprotective effects (92.3%, 88.2% and 82.1% survival, respectively) on cellsduring drying process whereas glycerol had the lowest protective effect onviability (15.4% survival).During storage of lyophilized cells at 35° C, 100% of cells are dead in alltreatments after 15 days. Unwashed cells treated with manitol, maltodextrinand spent growth medium showed 79.2%, 68.3% and 62.7% viability,respectively after keeping at 4°C for 6 months.There is direct relationship between the soluble protein contents of cells andstorage temperature. Cells stored at -20° C showed highest soluble proteincontents after 6 months of storage while the lowest amount of solubleprotein contents was detected in cells stored at 35° C. On the other hand,glucose dehydrogenase and gluconate dehydrogenase activities decreasedduring storage of cells at 4°C, whereas more than 90% of the enzymesactivity remained during storage of different cells at -20° C, so it can beassumed that higher temperature can inactivate cell proteins.spektrum | Tagungsband 2011