Comparison of molecular techniques for the detection of Toxoplasma gondii in raw bovine milk from small rural properties in Brazil

This study aimed to research Toxoplasma gondii DNA in 102 samples of raw bovine milk from expansion tanks, in small properties located in different cities of the Midwest region of São Paulo, Brazil. For this, polymerase chain reaction (PCR) was performed with the primers TOX4/TOX5 for cPCR (conventional PCR), TgNP1/TgNP2 gene for nested PCR and the Tg18s58F/Tg18s348R for nested PCR. It was possible to detect T. gondii DNA in 18 (17.65 %) milk samples from the 102 tanks, corresponding to 4.90 % for TOX4/TOX5 primers, 12.74 % for TgNP1/TgNP2 gene and 0.98 % for Tg18s58F/Tg18s348R gene. The results showed that the TgNP1 and TgNP2 genes were more efficient to detect T. gondii DNA, and also indicated the importance of raw bovine milk as a source of human infections caused by this protozoan, being a public health problem. It is important to continue studies involving T. gondii from bovine milk considering the need for proper pasteurization, and for better comprehension regarding the epidemiology of this protozoan.

Commercially acquired açaí pulps contamination by Trypanosoma cruzi

The etiological agent of Chagas disease is the protozoan Trypanosoma cruzi. According to the World Health Organization, about seven to eight million people are infected with T. cruzi worldwide. The main routes of transmission are vectorial and oral, which has assumed great epidemiological importance, since there is no legislation that requires the pasteurization of açaí pulp. The present work aimed to look T. cruzi in 35 samples of açaí ice cream sold at different points of sale, covering 11 different cities in São Paulo State. Thus, the parasitological technique of forced sieving and the molecular test of Polymerase Chain Reaction were performed. For PCR analysis were used the 121/122 primer that amplifies the kinetoplast of the T. cruzi DNA (kDNA). By the forced sieving technique, the açaí pulp aliquots were analyzed under different storage temperatures and in different periods. One positive sample (2.86%) were observed at six hours at room temperature, but without motility and negative to the PCR technique. Two other açaí samples (5.71%) were positive by PCR, but negative by forced sieving. The results indicate the need for quality control and good manufacturing practices for the safe consumption of açaí-derived products.

Application of culture-independent methods to assess the bacteria removal efficiency of subsurface flow constructed wetlands

The bacteriologic treatment efficiency of vertical and horizontal subsurface flow constructed wetlands (SFCWs) was analysed in two multistage wastewater treatment systems by culture dependent and independent methods. When assessed with standard cultivation procedures, bacteria removal efficiency of the vertical and horizontal SFCWs was similar. However, microscopic enumerations of the wastewater bacteria after DNA staining revealed a completely different removal pattern: bacteria removal efficiency of the horizontal SFCWs was in general low and erratic, whereas the vertical SFCWs displayed high bacteria removal rates. The discrepancies in the results obtained by bacteria enumeration and cultivation was due to a strong decrease in bacterial culturability after treatment by the horizontal SFCWs, leading to overestimation of the real bacterial concentrations in these effluents. Additionally, a PCR based approach for the detection of the enteropathogenic bacteria Campylobacter jejuni and Yersinia enterocolitica was tested in the wastewater samples. The methods were specific and reproducible in the analysed samples and could be carried out within 12 h, proving very adequate as an alternative to cultivation. This work recommends a review of the current standard methodology for wastewater quality surveillance, as well as of the design of SFCW.

Stable-isotope-based labeling of styrene-degrading microorganisms in biofilters

Deuterated styrene ([(2)H(8)]styrene) was used as a tracer in combination with phospholipid fatty acid (PLFA) analysis for characterization of styrene-degrading microbial populations of biofilters used for treatment of waste gases. Deuterated fatty acids were detected and quantified by gas chromatography-mass spectrometry. The method was evaluated with pure cultures of styrene-degrading bacteria and defined mixed cultures of styrene degraders and non-styrene-degrading organisms. Incubation of styrene degraders for 3 days with [(2)H(8)]styrene led to fatty acids consisting of up to 90% deuterated molecules. Mixed-culture experiments showed that specific labeling of styrene-degrading strains and only weak labeling of fatty acids of non-styrene-degrading organisms occurred after incubation with [(2)H(8)]styrene for up to 7 days. Analysis of actively degrading filter material from an experimental biofilter and a full-scale biofilter by this method showed that there were differences in the patterns of labeled fatty acids. For the experimental biofilter the fatty acids with largest amounts of labeled molecules were palmitic acid (16:0), 9,10-methylenehexadecanoic acid (17:0 cyclo9-10), and vaccenic acid (18:1 cis11). These lipid markers indicated that styrene was degraded by organisms with a Pseudomonas-like fatty acid profile. In contrast, the most intensively labeled fatty acids of the full-scale biofilter sample were palmitic acid and cis-11-hexadecenoic acid (16:1 cis11), indicating that an unknown styrene-degrading taxon was present. Iso-, anteiso-, and 10-methyl-branched fatty acids showed no or weak labeling. Therefore, we found no indication that styrene was degraded by organisms with methyl-branched fatty fatty acids, such as Xanthomonas, Bacillus, Streptomyces, or Gordonia spp.