Deodorizing bacterial consortium: community analysis of biofilms and leachate water collected from an air biofiltration system in a piggery.

Intensive livestock production is a source of water, soil, and air contamination. The first aspect that negatively affects the quality of life of residents in the vicinity of piggeries is malodorous aerosols, which are not only responsible for discomfort but can be an etiological factor in the development of various diseases during prolonged exposure. One of the proven and efficient ways to counteract odor emissions is the usage of air biofiltration. The purpose of this study was to qualitatively analyze the bacterial community colonizing the biofilm of a biofilter operating at an industrial piggery in Switzerland. The study material consisted of biofilm and leachate water samples. The microbiological analysis consisted of DNA isolation, amplification of the bacterial 16S rRNA gene fragment (V3-V4), preparation of a library for high-throughput sequencing, high-throughput NGS sequencing, filtering of the obtained sequencing reads, and evaluation of the species composition in the studied samples. The investigation revealed the presence of the following bacterial genera: Pseudochelatococcus, Methyloversatilis, Flexilinea, Deviosia, Chryseobacterium, Kribbia, Leadbetterella, Corynebacterium, Flavobacterium, Xantobacter, Tessaracoccus, Staphylococcus, Thiobacillus, Enhydrobacter, Proteiniclasticum, and Giesbergeria. Analysis of the microbial composition of biofilters provides the opportunity to improve the biofiltration process.

Assessment of antibiotic resistance and biofilm formation of Enterococcus species isolated from different pig farm environments in Poland.

BACKGROUND: Enteroccocus spp. are human opportunistic pathogens causing a variety of serious and life-threating infections in humans, including urinary tract infection, endocarditis, skin infection and bacteraemia. Farm animals and direct contact with them are important sources of Enterococcus faecalis (EFA) and Enterococcus faecium (EFM) infections among farmers, veterinarians and individuals working in breeding farms and abattoirs. The spread of antibiotic-resistant strains is one of the most serious public health concerns, as clinicians will be left without therapeutic options for the management of enterococcal infections. The aim of the study was to evaluate the occurrence and antimicrobial susceptibility of EFA and EFM strains isolated from a pig farm environment and to determine the biofilm formation ability of identified Enterococcus spp. strains. RESULTS: A total numer of 160 enterococcal isolates were obtained from 475 samples collected in total (33.7%). Among them, 110 of genetically different strains were identified and classified into EFA (82; 74.5%) and EFM (28; 25.5%). Genetic similarity analysis revealed the presence of 7 and 1 clusters among the EFA and EFM strains, respectively. The highest percentage of EFA strains (16; 19.5%) was resistant to high concentrations of gentamicin. Among the EFM strains, the most frequent strains were resistant to ampicillin and high concentrations of gentamicin (5 each; 17.9%). Six (7.3%) EFA and 4 (14.3%) EFM strains showed vancomycin resistance (VRE - Vancomycin-Resistant Enterococcus). Linezolid resistance was found in 2 strains of each species. The multiplex PCR analysis was performed to identify the vancomycin resistant enterococci. vanB, vanA and vanD genotypes were detected in 4, 1 and 1 EFA strains, respectively. Four EFA VRE-strains in total, 2 with the vanA and 2 with the vanB genotypes, were identified. The biofilm analysis revealed that all vancomycin-resistant E. faecalis and E. faecium strains demonstrated a higher biofilm-forming capacity, as compared to the susceptible strains. The lowest cell count (5.31 log CFU / cm2) was reisolated from the biofilm produced by the vancomycin-sensitive strain EFM 2. The highest level of re-isolated cells was observed for VRE EFA 25 and VRE EFM 7 strains, for which the number was 7 log CFU / cm2 and 6.75 log CFU / cm2, respectively. CONCLUSIONS: The irrational use of antibiotics in agriculture and veterinary practice is considered to be one of the key reasons for the rapid spread of antibiotic resistance among microorganisms. Owing to the fact that piggery environment can be a reservoir of antimicrobial resistance and transmission route of antimicrobial resistance genes from commensal zoonotic bacteria to clinical strains, it is of a great importance to public health to monitor trends in this biological phenomenon.

Effect of Radiant Catalytic Ionization and Ozonation on Salmonella spp. on Eggshells.

Three Salmonella enterica strains were used in the study (serovars: S. enteritidis, S. typhimurim and S. virchow). This study evaluated the efficacy of radiant catalytic ionization (RCI) and ozonation against Salmonella spp. on eggshell (expressed as log CFU/egg). The egg surface was contaminated three different bacterial suspension (103 CFU/mL, 105 CFU/mL and 108 CFU/mL) with or without poultry manure. Experiments were conducted at 4 °C and 20 °C in three different time period: 30 min, 60 min and 120 min. Treatment with RCI reduced Salmonella numbers from 0.26 log CFU/egg in bacterial suspension 108 CFU/mL, 4 °C and 20 °C, with manure for 30 min to level decrease in bacteria number below the detection limit (BDL) in bacterial suspension 105 CFU/mL, 20 °C, with or without manure for 120 min. The populations of Salmonella spp. on eggs treated by ozonizer ranged from 0.20 log CFU/egg in bacteria suspension 108 CFU/mL, 20 °C, with manure for 30 min to 2.73 log CFU/egg in bacterial suspension 105 CFU/mL, 20 °C, with manure for 120 min. In all treatment conditions contamination with poultry manure decrease effectiveness the RCI and ozonation. In summary, RCI technology shows similar effectiveness to the ozonation, but it is safer for poultry plant workers and consumers.

Prevalence and antimicrobial susceptibility of Listeria monocytogenes strains isolated from a meat processing plant.

INTRODUCTION AND OBJECTIVE: The ability of L. monocytogenes to create biofilm results in the higher resistance to disinfectants and determines the need to search for effective methods of eradication. The aim of the study was to assess the level of L. monocytogenes contamination in the environment of a meat processing plant. The sensitivity of tested isolates to various antimicrobials used for disinfection purposes was also estimated. MATERIAL AND METHODS: The samples were taken from raw materials, semi-finished and final products, as well as food contact surfaces inthe production hall and deli meat packaging department. The number of L. monocytogenes and the effect of eight different biocides on bacteria planktonic forms and biofilm formed on stainless steel and polypropylene was investigated. The effect of blood and albumin on L. monocytogenes resistance to disinfectants was also analysed. RESULTS: The prevalence of L. monocytogenes on food contact surfaces was estimated at 2.93% (10 of 340 swabs taken). The samples of raw and processed products were not contaminated. Various disinfectants reduced the growth of planktonic L. monocytogenes forms at both tested concentrations 0.5% and 0.1% (irrespective of time exposure). The highest efficacy against L. monocytogenes biofilm was reported for agents containing hydrogen peroxide. The reduction of bacteria number ranged from 6.93-7.21 log CFU × cm-2, and was dependent on the surface type and time of agent application. CONCLUSIONS: In this study, the effectiveness of various disinfectants against planktonic bacteria and Listeria biofilm was observed. For the majority of disinfectants, the extension of time exposure increased bacteria elimination from the biofilm. The presence of blood resulted in reduction of the antilisterial action of most of the disinfectants applied at low concentrations.

Pathogen Reduction Potential in Anaerobic Digestion of Organic Fraction of Municipal Solid Waste and Food Waste.

Anaerobic digestion (AD) is a commonly used method of processing waste. Regardless of the type of the used digestate (fertilizer, feedstock in case of solid-state fermentation, raw-material in case of thermal treatment) effective pathogen risk elimination, even in the case of high pathogen concentration is essential. An investigation of the survival time and inactivation rate of the Salmonella Senftenberg W775, Enterococcus spp., and Ascaris suum eggs during thermophilic anaerobic digestion performed on laboratory scale and confirmation of hygienization in full-scale operation were performed in this study. Except for sanitization efficiency, the AD process performance and stability were also verified based on determination of pH value, dry matter content, acidity, alkalinity, and content of fatty acids. The elimination of pathogen was met within 6.06 h, 5.5 h, and about 10 h for the Salmonella Senftenberg W775, Enterococcus spp., and Ascaris suum, respectively in the laboratory trials. The obtained results were confirmed in full-scale tests, using 1500 m3 Kompogas® reactors, operating in MBT Plant located in Poland. Sanitization of the digestate was achieved. Furthermore, the process was stable. The pH value, suspended solids, and ammonium content remained stable at 8.5, 35%, and 3.8 g/kg, respectively. The acetic acid content was noted between almost 0.8 and over 1.1 g/kg, while the concentration of propionic acid was noted at maximum level of about 100 mg/kg. The AD conditions could positively affect the pathogen elimination. Based on these results it can be found that anaerobic digestion under thermophilic conditions results in high sanitation efficiency.

Characteristics of Listeria monocytogenes Strains Isolated from Milk and Humans and the Possibility of Milk-Borne Strains Transmission.

Listeria monocytogenes is the etiological factor of listeriosis. The main source of these organisms is food, including dairy products. The aim was to determine the multiple correlations between the drug susceptibility, virulence genes (VGs), and biofilm formation on silicone teat cups of milk-borne and human L. monocytogenes strains. The spread of L. monocytogenes via contaminated teat rubbers was assessed. The L. monocytogenes strains recovered from milk (18), human blood (10), and the reference strain ATCC®19111™ were used in the study. Penicillin resistance was the most prevalent resistance in the milk isolates (n=8; 44.4%), whereas among clinical strains erythromycin resistance was predominating - (n=6; 60%). The most frequent VGs among strains isolated from milk were hlyA (100%) and plcB (100%) whereas in strains isolated from blood - hlyA (100%) and prfA (90%). All tested VGs were present in 50% of blood isolates and 11% of milk-borne strains. The strains isolated from milk formed a significantly stronger biofilm. The strains with more numerous virulence genes were resistant to more antibiotics and formed a stronger biofilm. It was shown that contaminated teat cups might contribute to the transmission of L. monocytogenes in the herd. It seems reasonable to monitor the occurrence of L. monocytogenes biofilm in a dairy processing environment.Listeria monocytogenes is the etiological factor of listeriosis. The main source of these organisms is food, including dairy products. The aim was to determine the multiple correlations between the drug susceptibility, virulence genes (VGs), and biofilm formation on silicone teat cups of milk-borne and human L. monocytogenes strains. The spread of L. monocytogenes via contaminated teat rubbers was assessed. The L. monocytogenes strains recovered from milk (18), human blood (10), and the reference strain ATCC®19111™ were used in the study. Penicillin resistance was the most prevalent resistance in the milk isolates (n=8; 44.4%), whereas among clinical strains erythromycin resistance was predominating ­ (n=6; 60%). The most frequent VGs among strains isolated from milk were hlyA (100%) and plcB (100%) whereas in strains isolated from blood ­ hlyA (100%) and prfA (90%). All tested VGs were present in 50% of blood isolates and 11% of milk-borne strains. The strains isolated from milk formed a significantly stronger biofilm. The strains with more numerous virulence genes were resistant to more antibiotics and formed a stronger biofilm. It was shown that contaminated teat cups might contribute to the transmission of L. monocytogenes in the herd. It seems reasonable to monitor the occurrence of L. monocytogenes biofilm in a dairy processing environment.

Drug-susceptibility, biofilm-forming ability and biofilm survival on stainless steel of Listeria spp. strains isolated from cheese.

The aim of the study was to analyze the contamination of mold cheese (Brie, Camembert, Gorgonzola, Munster and Roquefort) with Listeria spp. and assessment of culturable cells number recovered from the biofilm formed on the surface of stainless steel by obtained strains. Identified isolates (MALDI TOF MS technique) were subjected to susceptibility testing (disk-diffusion method) and their genetic similarity (PFGE method), ability to form biofilm (quantitative method), biofilm dry weight, and biofilm survival on stainless steel were evaluated. Out of 250 samples of cheese 26 (10.4%) were Listeria spp. positive, including 15 isolates (6.0% of samples) of L. monocytogenes, 7 isolates of L. innocua (2.8% of samples) and 4 isolates of L. welshimeri species (1.6% of samples). Of the 26 isolates tested, 22 strains were genetically different. It was shown that L. innocua and L. welshimeri strains were sensitive to all antibiotics tested, while two (16.7%) L. monocytogenes strains were resistant to penicillin and one (8.3%) to erythromycin. L. monocytogenes formed biofilm most intensively on stainless steel, while L. welshimeri the least effectively. The median of bacteria number recovered from the biofilm for L. monocytogenes was 6.81 log CFU × cm-2, for L. innocua - 5.63 log CFU × cm-2, and for L. welshimeri - 4.93 log CFU × cm-2. The survival in the biofilm of Listeria spp. strains decreased along with the increase in a storage temperature of steel coupons. The longest survival time was reported at 4 °C, i.e. 47.58-124.41 days, with an elimination rate of 0.06-0.13 log CFU × day-1. Collectively, L. monocytogenes is the most prevalent species of Listeria genus in the mold cheese. The ability of L. monocytogenes strains to form biofilm on stainless steel and survive in the food processing environment increases chance of the secondary contamination of food posing risk to the consumer health.

Effect of Selected Environmental Factors on the Microbicidal Effectiveness of Radiant Catalytic Ionization.

The aim of this study was the assessment of the effect of time exposure, temperature, distance, and organic contaminants on radiant catalytic ionization (RCI) microbicidal effectiveness. The number of all examined bacteria decreased together with time exposure of RCI. The lowest recovery was obtained, both from the rubber surface (6.36 log CFU × cm-2) and steel (6.04 log CFU × cm-2) in the case of Escherichia coli O157:H7. On the other hand, Staphylococcus aureus was isolated in the largest number (rubber: 7.88 log CFU × cm-2, steel: 7.79 log CFU × cm-2). Among the tested environmental conditions, the greatest bacterial population was re-isolated at 4°C (distance: 0.5 m, time: 24 h), whereas the lowest population was found at a distance of 0.5 m (temperature: 20°C, time: 24 h) and on surfaces without contamination. In the samples treated with RCI, the bacterial population was the lowest on non-contaminated surfaces, ranging from 3.76 log CFU × cm-2 (E. coli O157:H7) to 5.58 log CFU × cm-2 (S. aureus) for the rubber, and from 3.26 log CFU × cm-2 (E. coli O157:H7) to 5.20 log CFU × cm-2 (S. aureus) for the stainless steel. The highest bacteria number was isolated from surfaces contaminated with meat and fish pulp. The lowest bacterial reduction caused by RCI was found in the case of rubber contaminated with meat-fish pulp (24 h, 0.5 m, 20°C). The reduction rate was equal to 0.89 log CFU × cm-2 for S. aureus, 1.17 log CFU × cm-2 for Listeria monocytogenes, 1.43 log CFU × cm-2 for Salmonella Enteritidis and 1.61 log CFU × cm-2 for E. coli O157:H7. In turn, the greatest bacterial reduction was found in the case of non-contaminated steel (24 h, 0.5 m, 37°C). The reduction rate was equal to 4.52 log CFU × cm-2 for L. monocytogenes, 3.61 log CFU × cm-2 for S. Enteritidis, 2.98 log CFU × cm-2 for E. coli O157:H7 and 2.77 log CFU × cm-2 for S. aureus. RCI allows the inactivation of pathogens from stainless steel and rubber surfaces. Its efficacy is species-dependent and affected by environmental factors.

The occurrence, transmission, virulence and antibiotic resistance of Listeria monocytogenes in fish processing plant.

The aim of this research was to investigate the occurrence of Listeria monocytogenes in fish and fish processing plant and to determine their transmission, virulence and antibiotic resistance. L. monocytogenes was isolated according to the ISO 11290-1. The identification of L. monocytogenes was confirmed by multiplex PCR method. Genetic similarity of L. monocytogenes strains was determined with the Pulsed-Filed Gene Electrophoresis (PFGE) method. The multiplex PCR was used for identification of L. monocytogenes serogroups and detection of selected virulence genes (actA, fbpA, hlyA, iap, inlA, inlB, mpl, plcA, plcB, prfA). The L. monocytogens isolates susceptibility to penicillin, ampicillin, meropenem, erythromycin, trimethoprim/sulfamethoxazole was evaluated with disc diffusion method according to EUCAST v. 7.1. The presence of 237 L. monocytogenes isolates (before genetic similarity assessment) in 614 examined samples was confirmed. After strain differentiation by PFGE techniques the presence of 161 genetically different strains were confirmed. The genetic similarity of the examined isolates suggested that the source of the L. monocytogenes strains were fishes originating from farms. All tested strains possessed all detected virulence genes. Among examined strains, the most (26, 38.6%) belonged to the group 1/2a-3a. The most of tested strains were resistant to erythromycin (47.1%) and trimethoprim/sulfamethoxazole (47.1%).

Comparison of selected disinfectants efficiency against Listeria monocytogenes biofilm formed on various surfaces.

Listeria monocytogenes is a main etiological factor of listeriosis, spread mainly by food products. In recent years, an increasing number of patients with listeriosis and an augmentation in L. monocytogenes antibiotic resistance, e.g. to penicillin and ampicillin, has been reported. The aim of the study was to characterise the L. monocytogenes strains isolated from fish-processed food products. Species identification, based on the multiplex-PCR reaction, was performed, and the genetic similarity of the isolates was analysed with the RAPD technique. The strains, in the form of planktonic cells and a biofilm, were subjected to drug-susceptibility analysis, and the effect of disinfectants on the bacillus cells was evaluated. All of the analysed strains were of the Listeria monocytogenes species. Three genetically distant strains were detected, i.e. Lm I, Lm II and Lm III. Approximately 66.6% penicillin-resistant and 66.6% cotrimoxazole-resistant strains were found. No erythromycin-resistant strain was detected. The Lm II strain was simultaneously resistant to four antibiotics, i.e. penicillin, ampicillin, meropenem and cotrimoxazole. The strongest biofilm was formed on aluminium foil and the weakest on rubber. The tested disinfectant antibiofilm effectiveness was related to the type of surface. The most effective agent was paracetic acid and hydrogen peroxide (elimination rate 5.10-6.62 log CFU × cm-2 and 5.70-7.39 log CFU × cm-2 after 1- and 5-min exposure, respectively) and the least-sodium hydroxide (elimination rate 0.52-1.20 log CFU × cm-2 and 0.98-1.81 log CFU × cm-2 after 1- and 5-min exposure, respectively). Further studies on a greater number of L. monocytogenes strains are recommended.

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 personnel's 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.

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.

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.

Effects of spring season solar drying process on sanitation indicators in sewage sludge and potential as a method for fertilizer production.

The agricultural use of sewage sludge is possible on condition of maintaining microbiological and parasitological standards, and one of the most modern methods improving its sanitary state is solar drying. In the presented study, the effect of this process on the elimination of indicator microorganisms (Escherichia coli, Salmonella Senftenberg W775, Enterococcus spp.) and eggs of Ascaris suum introduced into the biomass of sludge was examined. The experiment was carried out in the spring period with a maximal temperature of 18 °C inside the drying plant. Bacteria and parasite eggs were introduced into special carriers (cylinders filled with sewage sludge) and placed at selected points of the drier. The carriers were removed every 7 days and subject to a research procedure in order to estimate the number of bacteria and percentage of live eggs of Ascaris suum. Sanitization of the material was not obtained, since after 28 days of the process the final product contained a large concentration of Enterococcus spp. and S. Senftenberg W775 (10(5) -10(9) MPNg(-1)). Only the number of E. coli decreased by 6 log. During the process, the fastest decrease in the number of bacteria was observed in E. coli (ca 0.2 log/day), slower in enterococci (0.02-0.081 log/day), and the slowest in bacilli of the genus Salmonella (0.011-0.061 log/day). Sludge after drying also still contained 57-66% of live eggs of A. suum. The study proved that the solar drying of sludge in the spring period results in a product which poses a hazard for public and animal health and environmental sustainability, and should not be used as a fertilizer.

The use of oak chips and coconut fiber as biofilter media to remove vocs in rendering process.

The study evaluated the effectiveness of air biofiltration in rendering plants. The biofilter material comprised compost soil (40%) and peat (40%) mixed up with coconut fiber (medium A) and oak bark (medium B). During biofiltration average VOCs reduction reached 88.4% for medium A and 89.7% for medium B. A positive relationship of aldehyde reduction from material humidity (r = 0.502; α<0.05) was also noted. Other biomaterial parameters did not affect the treatment efficiency.

Sanitization efficacy of anaerobic digestion and aeration of slurry from the aspect of limiting emission of Salmonella into the environment.

The aim of this study was to estimate the usefulness of mesophilic anaerobic digestion and aeration for sanitization of slurry from the aspect of limiting transmission of Salmonella into the environment. Material for the study was fresh pig slurry. Collected samples were subjected to anaerobic digestion at 35°C and aeration with an initial temperature of 35°C. The efficacy of both methods was examined based on determination of the elimination rate and theoretical time of survival of Salmonella Senftenberg W(775), Salmonella Enteritidis and Salmonella Typhimurium introduced into slurry in carriers of type Filter-Sandwich. Samples for the study were collected every 24 hours and the number of bacilli was determined with the MPN (Most Probably Number) method. The study indicated that fermentation is a more effective method for slurry sanitization. A higher rate of elimination and shorter time of survival of all the tested bacteria was observed, compared with the use of aeration. The experiment allowed us to prove the high sanitization efficacy of both examined methods. They ensure the full elimination of the tested serotypes of Salmonella in only slightly more than 10 days. The use of fermentation or aeration as a way of slurry treatment for agricultural purposes makes it possible to obtain a fertilizer which is valuable and safe for humans and the environment.

The influence of cadmium on life-history parameters and gut microflora of Archegozetes longisetosus (Acari: Oribatida) under laboratory conditions.

We tested the effect of cadmium (25, 130 microg Cd g(-1)), administered via Chinese cabbage (Brassica chinensis L.) as food on life-history parameters and gut microflora of tritonymphs and adults of the oribatid mite, Archegozetes longisetosus Aoki. Both concentrations of Cd had an adverse effect on offspring mortality, and the higher concentration also reduced female fecundity, as well as the number of bacteria, fungi and actinomycetes, and it changed the community structure of bacteria; the proportion of gram-negative bacteria increased while that of gram-positive bacteria declined. Interestingly, at the lower Cd concentration microflora was more abundant and diverse than in the control group, especially in the tritonymphs, although the mean activity of gut microflora was reduced. The higher Cd concentration reduced microflora activity both in the tritonymphs and adults.