Influence of the Presence of Long Chain Fatty Acids (Lcfas) in the Sewage on the Growth of M. Parvicella in Activated Sludge Wastewater Treatment Plants

Foaming and bulking problems in activated sludge treatment plants are associated to the presence of a variety of filamentous bacteria. However, it has been observed that M. parvicella is the most frequent filamentous microorganism causing sludge bulking and foaming, especially in treatment plants involving nutrients removal. High sludge retention time, low DO, low temperature, presence of anoxic, anaerobic, and intermittently aerated zones, are the most commonly cited conditions associated with its growth. Substrate composition is another significant factor, as it has been found that slowly degradable organic material may favour the growth of M. parvicella. If has also been suggested that M. parvicella may preferably store long chain fatty acids (LCFAs) under anaerobic conditions and subsequently use it for growth. The paper presents the results of an investigation conducted at the wastewater treatment plant of Ioannina, aiming to establish a cause-effect relationship between the presence of LCFAs and the abundance of M. parvicella. This investigation is a part of a wider study sponsored by the Greek Secretariat for Research, under the PENED programme. The duration of the investigation covers 8 months, from January 2004 to August 2004. During this period samples were taken from the sewage collection network and wastewater treatment plant of Ioannina and analysed for, among other parameters, LCFAs and total fatty acids while samples of the mixed liquor and the foam in the biological reactors were microscopically analysed in order to determine the presence and amount of various types of filamentous bacteria. Two main conclusions were drawn. The first is related to the effect of temperature on the growth of M. parvicella, indicating that the growth of this specific filamentous bacterium is favoured by low temperatures (generally below 20 oC), while higher temperatures cause the practical elimination of M. parvicella, irrespectively of other factors. This conclusion verifies previous studies in pilot units and full scale plants. The second conclusion is that during winter periods there seems to be a positive correlation, between the presence of fatty acids and more specifically LCFAs and the amount of M. parvicella.

Isolation and Characterization of a New Arthrospira Strain

A filamentous microorganism, morphologically similar to the cyanobacterium Arthrospira, was isolated from Mangueira Lagoon in Brazil, from which Arthrospira has not previously been isolated. Random amplified polymorphic DNA (RAPD) comparison with the standard Arthrospira platensis strains LEB 52 and Paracas indicated that the organism isolated was an Arthrospira isolate, which we denominated strain LEB 18. The RAPD analysis showed conserved sequences which indicated that the three strains belonged to the same genus, and were all Arthrospira species, but there were sufficient differences between them suggesting that they were separate strains. The strain LEB 18 was cultivated in undiluted Zarrouk medium and in 60% and 20% (v/v) Zarrouk medium diluted with sterilized Mangueira Lagoon water (MLW) using illuminance rates of 32.5, 45.5 and 58.5 μmol m−2 s−1 according to a complete 32 factorial design with a triplicate central point. The strains LEB 52 and Paracas were cultived in the conditions central point. Our new isolate produced the highest specific growth rate (μmax = 0.22 d−1) in 60% Zarrouk medium diluted with MLW and illuminated with 58.5 μmol m−2 s−1 and the highest protein content (86.0% w/w).

Nocardiosis and kidney transplantation: case report in a recently transplanted patient

The patient is a 47-year-old white woman who was on the hemodialysis from 1999 to 2002, when she received a cadaveric renal transplant (deceased donor). The immediate postoperative immunosupression consisted of oral tacrolimus, predinisone and mycofenolato mofetil (MMF), and her medications at that time of her admission were tacrolimus (5mg 12/12 h), MMF (1000mg 12-12 h), and predinisone (10mg/ day). After 8 weeks, the patient went to the hospital and she was admitted presenting fever (37,9ºC), cough, malaise and vomiting. The chest radiography revealed a mass in the left superior lobe, which was initially treated with levofloxacin associated to ceftriaxone. There was partial improvement of the cough and total remission of the fever. The patient was discharged after 3 weeks of treatment in stable condition, with negative blood and bronchial cultures. After ten days, she returned to the hospital with relapsed symptoms and a subcutaneous purulent collection was detected in her left leg, and the culture of the drained material evidenced a filamentous microorganism, identified as Nocardia sp, later specified as Nocardia asteroides. Treatment with sulfametoxazole-trimetroprin 800mg t.i.d was initiated, and after five days, the patient was pyretic and treatment was kept for six months.