Diversity and variability of methanogens during the shift from mesophilic to thermohilic conditions while biogas production.

Anaerobic digestion (AD) is the most popular path of organic waste disposal. It is often used in wastewater treatment plants for excessive sludge removal. Methanogenic fermentation had usually been performed under mesophilic conditions, but in the past few years the thermophilic processes have become more popular due to economics and sludge sanitation. Methanogens, the group of microorganisms responsible for methane production, are thought to be sensitive to temperature change and it has already been proven that the communities performing methanogenesis under mesophilic and thermophilic conditions differ. But in most cases the research performed on methanogen diversity and changeability was undertaken in two separate anaerobic chambers for meso- and thermophilic conditions. It is also known that there is a group of microorganisms performing AD which are insensitive to temperature. Also the linkage between digester performance and its microbial content and community changeability is still not fully understood. That is why in this experiment we analyzed the bacterial community performing methanogenesis in a pilot scale anaerobic chamber during the shift from mesophilic to thermophilic conditions to point at the group of temperature tolerant microorganisms and their performance. The research was performed with PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis). It occurred that the community biodiversity decreased together with a temperature increase. The changes were coherent for both the total bacteria community and methanogens. These bacterial shifts were also convergent with biogas production-it decreased in the beginning of the thermophilic phase with the bacterial biodiversity decrease and increased when the community seemed to be restored. DGGE results suggest that among a wide variety of microorganisms involved in AD there is a GC-rich group relatively insensitive towards temperature change, able to adapt quickly to shifts in temperature and perform AD effectively. The studies of this microbial group could be a step forward in developing more efficient anaerobic digestion technology.

The ability of Azolla caroliniana to remove heavy metals (Hg(II), Cr(III), Cr(VI)) from municipal waste water.

The aim of this paper was to investigate the capacity of a small water fern, Azolla caroliniana Willd. (Azollaceae), to purify waters polluted by Hg and Cr. Many plants are capable of accumulating heavy metals (called hyperaccumulators) and one of them is the water fern A. caroliniana. During 12 days of the experiment the fern was grown on the nutrient solution containing Hg2+, Cr3+ and CrO4(2-) ions, each in a concentration 0.1, 0.5 and 1.0 mg dm(-3). The presence of these ions caused a 20-31% inhibition of A. caroliniana growth, the highest in the presence of Hg(II) ions, in comparison to the control. After day 12 of the experiment, metal contents the solution decreased to 0-0.25 mg dm(-3), and this decrease comprised between 74 (Cr3+ 1.0 mg dm(-3) treatment) and 100% (CrO4(2-) 0.1 mg dm(-3) treatment). The fern took a lesser quantity of the metals from 0.1 mg dm(-3) treatments compared to 0.5 and 1.0 mg dm(-3) treatments. In the A. caroliniana tissues the concentration of heavy metals under investigation ranged from 71 to 964 mg kg(-1) dm; the highest level being found for Cr(III) containing nutrient solution.

[Analysis of unsuccessful outcomes in a group of pregnancies with diabetes from the intensive care clinic of the Institute of Obstetrics and Gynecology in Poznan during the years 1988-1993]. / Analiza niepowodzen polozniczych w grupie ciezarnych z cukrzyca w KIN IGIP AM w Poznaniu w latach 1988-1993.

In the present paper we analysed 416 diabetic pregnant women, treated in the Intensive Care Clinic--Poznan, between 1988-93. We found in this period 8 (1.93%) stillbirth, 6 (1.44%) perinatal deaths and 4 (0.96%) deaths in neonatal period. It was together 18 fetal and neonatal deaths, which gives 4.33 per cent of perinatal and neonatal mortality rate. Four newborns died because of RDS, 2 with congenital anomalies (pulmonary hypoplasia), 3 with heart defects and 1 with oesophagus anomaly. Only 3 diabetic pregnant women of the total 18, were under special care from the I trimester, and almost all been difficult to normalize the glycemia. Only in 6 cases this group glycemia profile was below 100 mg/dl, in other 8 cases this value was above 120 mg/dl. Unsuccessful outcomes mostly occurred in women with long--lasting diabetes and with vascular complications. This study prove, that despite substantial reduction of perinatal mortality rate in children of diabetic mothers, diabetes still is a cause of congenital anomalies, as well as fetal anoxia. Special adverse impact of diabetes on the development of the fetus is observed in long--lasting diabetes and uncontrolled metabolism.