The book bridges the gaps in providing information about Microbes that younger people with no technical knowledge can understand. Also, this book is a nice starting place for research on Microbes for students in high school or college.

The radiation resistances of the bioburden of cut-gut sutures filled with isopropyl-alcohol solution (IPA) were studied. In order to maintain the reliability of delivered doses, Ceric-cerous dosimeters (the facility standard) were calibrated with NPL alanine dosimeters and uniform dose rate areas in the gamma irradiation field were established. The doses measured for 3 batches by a Cericcerous dosimeter were equal to the difference within an accuracy of +-2% and the measured doses between Fricke-dosimeter and Ceric-cerous(E98) dosimeter agreed within about 2.3%. Recovery methods of natural bioburden from the sutures were validated by a double filtration method. Reciprocal-shaker treatment showed high recovery efficiency for the bioburden. The bioburden consisted of 5 types of spore forming bacteria and the most radiation-resistant strain was identified as Bacillus megaterium, which occupies 6.1% of all (473 isolates). The radiation-resistances of the bacteria were 2.33kGy in IPA solution and 2.15kGy in dried TSB. Using the distribution of radiation-resistance of the bioburden, the doses required for 10E-2or 10E-6 SAL were calculated. It was found that ISO Method 1 gives a higher 10E-6 SAL dose in spite of a lower 10E-2 SAL dose at over 0.56 of average bioburden, compared with these for the suture.

The phosphate-solubilizing potential of the rhizosphere microbial community in mangroves was demonstrated when culture media supplemented with insoluble, tribasic calcium phosphate, and incubated with roots of black (Avicennia germinans L.) and white [Laguncularia racemosa (L.) Gaertn.] mangrove became transparent after a few days of incubation. Thirteen phosphate-solubilizing bacterial strains were isolated from the rhizosphere of both species of mangroves: Bacillus amyloliquefaciens, Bacillus licheniformis, Bacillus atrophaeus, Paenibacillus macerans, Vibrio proteolyticus, Xanthobacter agilis, Enterobacter aerogenes, Enterobacter taylorae, Enterobacter asburiae, Kluyvera cryocrescens, Pseudomonas stutzeri, and Chryseomonas luteola. One bacterial isolate could not be identified. The rhizosphere of black mangroves also yielded the fungus Aspergillus niger. The phosphate-solubilizing activity of the isolates was first qualitatively evaluated by the formation of halos (clear zones) around the colonies growing on solid medium containing tribasic calcium phosphate as a sole phosphorus source. Spectrophotometric quantification of phosphate solubilization showed that all bacterial species and A. niger solubilized insoluble phosphate well in a liquid medium, and that V. proteolyticus was the most active solubilizing species among the bacteria. Gas chromatographic analyses of cell-free spent culture medium from the various bacteria demonstrated the presence of 11 identified, and several unidentified, volatile and nonvolatile organic acids. Those most commonly produced by different species were lactic, succinic, isovaleric, isobutyric, and acetic acids. Most of the bacterial species produced more than one organic acid whereas A. niger produced only succinic acid. We propose the production of organic acids by these mangrove rhizosphere microorganisms as a possible mechanism involved in the solubilization of insoluble calcium phosphate.

The mikroflorra of four zeolite substrates differ in degree of saturation with nitrogen (0.1, 0.2, 0.4 and 0.8% N) raw zeolite and fluvy soil, as a control were studied. The study included one substrate recultivated with nutritional elements after its exhausting in result of four years exploitation. The mikroflora of the substrates and the soil was established by evaluation of the amount of basic groups of microorganisms determining the biological activity of the soil. Minimal amounts of microorganisms have been found in raw zeolite. The biocenose of the zeolite substrates was not different from the tipical soil biocenose. The highest total amount of microorganisms have been found in the substrate containing the lowest amount of nitrogen (1.0%) - 5.31 million microorganisms per 1 g dry material compared to the control 3.49 million microorganisms per g soil. The recultivated substrate shows also high activity - 3.93 million microorganisms per 1 g material.

High hydrostatic pressure inactivation of Escherichia coli, Pseudomonas fluorescens, Listeria innocua, Staphylococcus aureus, and Lactobacillus helveticus were studied. These microorganisms were inoculated at a concentration between 10(7) and 10(8) cfu/ml in Ringer solution and in ovine milk adjusted to 0, 6, and 50% fat content to evaluate the baroprotective effect of fat content on inactivation of microorganisms. Treatments of pressurization consisted of combinations of pressure (100 to 500 MPa) and temperature (4, 25, and 50 degrees C) for 15 min. Gram-negative microorganisms were more sensitive than were Gram-positive ones (more destruction P. fluorescens > E. coli greater than or equal to List. innocua > Lb. helveticus > S. aureus). Pressurizations at low temperature (4 degrees C) produced greater inactivation on P. fluorescens, List. innocua, and Lb. helveticus than at room temperature (25 degrees C), whereas for E. coli and S. aureus the results were opposite. Ovine milk per se (0% fat) showed a baroprotective effect on all microorganisms, but percentage of fat (6 and 50%) did not show a progressive baroprotective effect in all pressurization conditions or for all microorganisms.

This work is a part of the project “Wood in the Food industry”, which have participants from all Nordic countries. The project is co-ordinated by the Norwegian Institute of Wood Technology and funded by the Nordic Wood. The aim of the present studies has been to study heat treatment of wood as a method to reduce the number of microorganisms to an acceptable hygienic level. The experiments are referring to activity no 4 and no 6 in the project; cleaning methods and hygienic limit values. Surfaces of wood were contaminated with either Halobacterium salinarum or microorganisms isolated from cod. The contaminated wood was then incubated at different time intervals and then heated at different temperatures and time intervals. The recovery of microbes after heat treatment was measured using both the swabbing and the contact method. The experiments show that heating can be used as a method to reduce the number of microorganisms on a wooden surface to an acceptable level. The required heating conditions (temperature, time) differ depending on the microorganisms present in the product and environment. Moist heat has better penetrating power than dry heat and causes a faster reduction of the number of living organisms at a given temperature. It seems that the time of incubation of the contaminated sample before the heat treatment is of vital importance to the detection of the microorganisms. | Wood in Food – hygienic limits and cleaning procedures. Partial report 2 | publishedVersion

The microorganisms Pseudomonas fragi, Brochotrix thermosphacta, Serratia liquefaciens or Hafnia spp., Acinetobacter spp., Psychrobacter spp are often isolated from meat. The growth of microorganisms can be inhibited by vacuum packaging or packaging in modified atmospheres such as those with a high concentration of CO2.

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