Zbigniew Paluszak

UV-C Radiation as a Factor Reducing Microbiological Contamination of Fish Meal

Fish meals, added to feeds as a source of protein, may contain pathogenic bacteria. Therefore, effective methods for their sanitizing, such as UV-C radiation, are needed to minimize the epidemiological risk. The objective of this study was to evaluate the effect of UV-C radiation on the sanitary state of fish meals. The research materials included salmon and cod meals. Samples of the fish meals were inoculated with suspensions of Salmonella, E. coli, enterococci, and C. sporogenes spores and exposed to the following surface UV-C fluencies: 0–400 J·m−2 for bacteria and 0–5000 J·m−2 for spores. For the vegetative forms, the highest theoretical lethal UV-C dose, ranging from 670.99 to 688.36 J·m−2 depending on the meal type, was determined for Salmonella. The lowest UV-C fluency of 363.34–363.95 J·m−2 was needed for the inactivation of Enterococcus spp. Spores were considerably more resistant, and the UV-C doses necessary for inactivation were 159571.1 J·m−2 in salmon meal and 66836.9 J·m−2 in cod meal. The application of UV-C radiation for the sanitization of fish meals proved to be a relatively effective method for vegetative forms of bacteria but was practically ineffective for spores.

Occurrence of amylolytic microorganisms in soil depending on the type of cultivation

Abstract The count and growth dynamics of amylolytic microorganisms in soil beyond rhizosphere and within rhizosphere as well as in potato rhizoplane was compared in ecological (organic) and conventional farming systems. Potatoes in the ecological system were fertilized only with organic fertilizers and in the conventional system NPK fertilizers + manure were used. The results showed that the count of bacteria showing amylolytic activity was generally higher in ecological farming than in conventional one. Vegetation stage had a significant effect on the growth dynamics of microorganisms tested. The highest level of their count was achieved at the end of the vegetation during tuber harvest maturity. A remarkable smaller count of microorganisms secreting amylases was recorded in the soil beyond rhizosphere in comparison with the rhizosphere area and rhizoplane. Selected physico-chemical properties of soils (humidity and pH) were more favourable in the soil cultivated under organic farming system in comparison to the conventional one.

Effect of Microwave Radiation on Microorganisms in Fish Meals

Abstract This study was aimed at testing the effect of microwave radiation on survival of E. coli, Salmonella Enteritidis, Enterococcus spp. and Clostridium spores in two kinds of fish meals. The material used in the study consisted of samples of two kinds of fish meal – salmon and cod. In the experiment samples of both kinds of fish meals were inoculated with suspensions of tested bacteria and spores of Clostridum sporogenes. After inoculation the material was exposed to microwave radiation with a frequency of 2.45 ghz and microwave energy power of 0, 100, 180, 300, 450, 600 and 700 w, respectively, for 2.5 min for bacteria and 11 minutes for spores. then the reisolated microorganisms were counted and theoretical lethal doses of radiation were determined. among the studied vegetative forms of bacteria, the largest decreases in the numbers at the same radiation dose were observed in the rods of E. coli, whereas the smallest in enterococci. spores of Clostridium sporogenes showed a considerably higher resistance to the effect of that factor. the power of dose resulting in the complete inactivation of the studied bacteria should be about 430 kJ×g–1, and in the case of spores – 1 900 kJ×g–1.

Sludge composting validation for minimizing environmental hazards. Anew indirect method of sanitation effectiveness assessment

Abstract The main purpose of the study was to assess a new sewage sludge composting validation method based on the survival of indicator microorganisms (Escherichia coli, Salmonella senftenberg W775, streptococci group D) introduced into composting piles. The experiment was carried out during summer and winter seasons. The piles were aerated mechanically by turning. The results obtained in the summer cycle showed that the time needed for the total inactivation of the indicatory bacteria in samples from three layers of the pile (top, middle, bottom) did not exceed 9 days. In winter the elimination of the indicatory microorganisms was longer and lasted from 29 days in the center of the pile to 60 days at the bottom layer. The implemented method for the estimation of sludge composting hygienization effectiveness is very useful and contributes to minimizing soil and ground water contamination.

Effects of green algae and napa cabbage on life-history parameters and gut microflora of Archegozetes longisetosus (Acari: Oribatida) under laboratory conditions

Abstract We compared the effect of green algae (dominated by Protococcus sp.) and the earlier studied napa cabbage on the life-history parameters and gut microflora of the oribatid mite Archegozetes longisetosus (a chelicerate model organism). Napa cabbage contained more crude ash, protein, and crude fibre than green algae, but A. longisetosus developed better on the latter food, displaying higher fertility, lower mortality of offspring and shorter development than on napa cabbage. The gut microflora of A. longisetosus depended on the kind of food and developmental stage of this mite. The adults fed with napa cabbage had more abundant and more active microflora than those fed with green algae, whereas in the tritonymphs the microflora was more abundant when they were fed with green algae, and was more active in the group fed with napa cabbage. Irrespective of the treatment, the highest percentage of the isolated bacteria were gram-positive bacilli or gram-negative bacteria, but the mites feeding on Protococcus sp. contained no cocci, whereas those fed with cabbage had no gram-positive bacteria.

Prevalence and distribution of VRE (vancomycin resistant enterococci) and VSE (vancomycin susceptible enterococci) strains in the breeding environment

INTRODUCTION Intensive animal production causes numerous problems. Facilities connected with animal maintenance not only cause environmental pollution, but also pose a great sanitary and epidemiological threat. Long-term use of antibiotics in animal production lead animal-borne microorganisms to develop multiple resistance mechanisms, transferred to the typical environmental bacteria. OBJECTIVE The aim of this study was assessment of E. faecalis, E. faecium, E. durans and E. hirae prevalence in samples gathered from swine production sectors, and determination of the contribution of VRE (vancomycin resistant enterococci) strains and their resistance. The degree of relationship between isolates of each species from genus Enterococcus was also determined. MATERIALS AND METHOD 195 isolates were obtained, from which DNA was isolated. Genus identification was conducted with the primers specific to the 16S rRNA region, and identification of the species with primers specific to sequence of gene sodA in Multiplex PCR reaction. Resistance to vancomycin (6 μg×ml -1 ) was tested using a screening method on Muller Hinton Agar. To assess resistance type Multiplex PCR, amplifying products corresponding to genes VanA, VanB and VanC, was conducted. Genotyping was conducted using the PCR-RAPD method. RESULTS Among the 195 isolates, 133 (68%) belonged to E. hirae. The other species contributions were respectively: E. faecalis - 21%, E. durans - 8% and E. faecium - 3%. Only 2 isolates of E. hirae, being different strains, were resistant to vancomycin. Both were representing phenotype VanC1. 60 genetically different strains were defined. The possible contamination paths involved animal feed and spreading of excrements by slaughtered individuals or on personnels footwear. CONCLUSIONS The obtained results indicate a very low percentage of VRE strains in the tested piggery, resulting in a low health risk to piggery, slaughterhouse or abattoir employees.

Aeration as an effective method for pathogen elimination in pig slurry

Abstract The aim of this study was to investigate the effect of aeration on the survival of indicator and pathogenic microorganisms in pig slurry. After inoculation of the aerated biomass with target bacteria, samples for the microbiological analyses were collected in different time intervals for the period of 12 days. The MPN method was used to determine the number of the investigated microorganisms. The results of statistical analysis showed the lack of significant differences in the theoretical time of survival, elimination rate and the time needed for 90% reduction between different Salmonella serotypes. Theoretical survival of Salmonella Typhimurium, Salmonella Senftenberg W775 and enterococci in the aerated slurry ranged from 13 to 25 days. Enterococci were the most resistant to aeration, and their survival time, compared to salmonellas, was significantly higher.

Viability of Clostridium sporogenes spores after CaO hygienization of meat waste.

The occurrence of the pathogenic species C. perfringens and C. botulinum spores in animal by-products poses a potential epidemiological hazard. Strong entero- and neurotoxins produced by these bacteria adversely affect human health. To inactivate pathogens present in animal by-products, waste must be subjected to various methods of sanitization. The aim of the presented study was to estimate the effect of different doses of CaO on the viability of spores Clostridium sporogenes in meat wastes category 3. During the research, two doses of burnt lime were added to the poultry mince meat and meat mixed with swine blood contaminated with Clostridium sporogenes spore suspension. Half of the samples collected for microbiological analyses were buffered to achieve the pH level ~7, the other were examined without pH neutralization. To estimate the spore number, 10-fold dilution series in peptone water was prepared and heat-treated at 80 °C for 10 min. After cooling-down, one milliliter of each dilution was pour-plated onto DRCM medium solidified with agar. Statistical analysis were performed using the Statistica software. Application of 70% CaO caused complete inactivation of Clostridium spores in meat wastes after 48 hours. The highest temperature achieved during the experiment was 67 °C. Rapid alkalization of the biomass resulted in increasing pH to values exceeding 12. The effect of liming was not dependent on the meat wastes composition nor CaO dose. The experiment proved the efficiency of liming as a method of animal by-products sanitization. Application of the obtained results may help reduce the epidemiological risk and ensure safety to people handling meat wastes at each stage of their processing and utilization.

Występowanie potencjalnie antagonistycznych bakterii w stosunku do patogenicznych grzybów na powierzchni korzeni ziemniaka (Solanum tuberosum) [Occurrence of potentially antagonistic bacteria on surface of potato (Solanum tuberosum) roots]

The research was carried out on farms in Kielpin in Bory Tucholskie Landscape Park in vicinity of Tuchola over 1997-1999. The purpose was to determine of quantitative composition of Pseudomonas and Artrobacter genera, coryneform group and total count of bacteria on roots of potato. Aster cultivar of potato was cultivated in two systems: conventional and ecological. The microbiological analysis showed that the coryneform group dominated over other investigated groups of bacteria. The greatest number of bacteria was isolated from rhizoplane of potatoes cultivated in ecological system. The results obtained during three years of the experiment show that the nmnber of potentially antagonistic bacteria increased along with plant vegetation. The maximum number of these bacteria inhabited roots of older plants.

Microbiological Evaluation of the Effectiveness of Sewage Sludge Sanitization with Solar Drying Technology

The aim of study was to estimate the sanitization effectiveness of the sludge solar drying process carried out on technical scale in Poland based on the inactivation of bacteria and parasite eggs. Sewage sludge samples inoculated with Escherichia coli, Salmonella Senftenberg W775 and enterococci and perlon bags containing Ascaris suum eggs were placed inside the carriers fixed in the dried sludge pile and on the shovels and frame of the sludge turner. The number of reisolated microorganisms was determined with MPN method and the percentage of invasive A. suum eggs—with the microscope counting. On the basis of regression equations, the theoretical survivability and elimination rate of bacteria and parasite eggs were calculated. Experiment showed low hygienization efficiency of solar drying method. The theoretical survival time was 46–104 days in summer and 90–98 days in winter for S. Senftenberg W775 and, respectively 42–55 and 71–148 days for E. coli, depending on the carriers location. Enterococci were able to survive for 52–168 days in summer and in winter its number increased. The decrease in the percentage of invasive A. suum eggs was almost not observed. Results indicated that solar drying is a technology, which does not guarantee biosafety of product.