Perinatal calf mortality in dairy herds has been reported worldwide. The etiology of stillbirth is multifactorial, and can be caused by various species of bacteria and environmental factors. Among them some potential pathogens from the Mollicutes class such as Mycoplasma (M.) spp. and Ureaplasma (U.) diversum can be isolated from the bovine genital tract and other organs of the suspected cattle. The aim of this study was to evaluate if the bacteria belonging to the Molli- cutes class i.e. M. bovis, M. bovigenitalium, M. canadense, M. canis, M. arginini, M. bovirhinis, M. dispar, M. alkalescens and U. diversum could have an impact on perinatal calf mortality in selected Polish dairy farms. The material was: 121 stillborn calves (SB), 21 live born calves (C) and 131 cows (dams) from 30 Polish Holstein-Friesian herds. Samples were examined from all the SB calves’ and six control euthanized calves’ abomasal contents and lung samples collected during necropsy, and from the dams’ serum and placenta. In dams the serological ELISA, and in calves and placenta samples molecular PCR/denaturing gradient gel electrophoresis, methods were used. Screening of dams’ sera for antibodies to M. bovis (ELISA) showed seven dams positive for M. bovis, whereas none of the nine examined Mollicutes microorganisms were detected in the placenta and calves.
Nitritation, the first stage of ammonia removal process is known to be limiting for total process performance. Ammonia oxidizing bacteria (AOB) which perform this process are obligatory activated sludge habitants, a mixture consisting of Bacteria, Protozoa and Metazoa used for biological wastewater treatment. Due to this fact they are an interesting bacterial group, from both the technological and ecological point of view. AOB changeability and biodiversity analyses both in wastewater treatment plants and lab-scale reactors are performed on the basis of 16S rRNA gene sequences using PCR-DGGE (Polymerase Chain Reaction – Denaturing Gradient Gel Electrophoresis) as a molecular biology tool. AOB researches are usually led with nested PCR. Because the application of nested PCR is laborious and time consuming, we have attempted to check the possibility of using only first PCR round to obtain DGGE fingerprinting of microbial communities. In this work we are comparing the nested and non-nested PCR-DGGE monitoring of an AOB community and presenting advantages and disadvantages of both methods used. The experiment revealed that PCR technique is a very sensitive tool for the amplification of even a minute amount of DNA sample. But in the case of nested-PCR, the sensitivity is higher and the template amount could be even smaller. The nested PCR-DGGE seems to be a better tool for AOB community monitoring and complexity research in activated sludge, despite shorter fragments of DNA amplification which seems to be a disadvantage in the case of bacteria identification. It is recommended that the sort of analysis approach should be chosen according to the aim of the study: nested-PCR-DGGE for community complexity analysis, while PCR-DGGE for identification of the dominant bacteria.