For this study, we isolated Helicobacter pylori from wastewater by a series of steps beginning with immunomagnetic separation and cell culture. After Gram staining and three standard microbial tests, the 16S rRNA sequences of a total of 23 out of 37 putative H. pylori isolates were verified by PCR. Eleven H. pylori isolates were genotyped and fell into four vacA classes: those with the vacA allelic variants s1a and m1, s1b and m1, s2 and m2, or s2 and m1. Most H. pylori isolates were of the vacA s1a/m1 type, which has been shown to be associated with advanced diseases based on genotyping of H. pylori from gastric cancer patients. These results demonstrated that H. pylori survives in water and may be a potential source of H. pylori transmission, especially where water is not adequately treated.

Purified phycobilisomes of Porphyridiwm cruentum were solubilized in sodium dodecyl sulfate and resolved by sodium dodecyl sulfate-acrylamide gel electropboresis into nine colored and nine colorless polypeptides. The colored polypeptides accounted for about 84% of the total stainable protein, and the colorless polypeptides accounted for the remaining 16%. Five of the colored polypeptides raning in molecular weight from 13,300 to 19,500 were identified as the a and ,8 subunits of aflophycocyanin, R-phycocyanin, and phycoerythria Three others (29,000-30,500) were orange and are probably related to the y subunit of phycoerythrin. Another colored polypeptide had a molecular weight of 95,000 and the characteristics of long wavelength-emitting aBophycocyanin. Sequential dissociation of phycobilisomes, and analysis of the polypeptides in each fraction, revealed the association of a 32,500 molecular weight colorless polypeptide with a phycoerythrin fraction. Tne remaining eight colorless polypeptides were in the core fraction of the phycobilisome, which also was enriched in allophycocyanin. In addition, the core fraction was enriched in a colored 95,000 dalton polypeptide. Inasmuch as a pobpeptide with the same molecular weight is found in thylakoid membranes (free of phycobilisomes), it is suggested that this polypeptide is involved in anchoring phycobilisomes to thylakoid membranes.

Two pigmented polypeptides with the same molecular weight (Mr 95,000) were isolated from the photosynthetic apparatus of Porphyridium cruentum by sodium dodecyl sulfate/ polyacrylamide gel electrophoresis. A blue polypeptide from phycobilisomes had absorption and fluorescence emission spectra similar to those of allophycocyanin. A green-pigmented polypeptide from photosynthetic membranes (free of phycobilisomes) contained chlorophyll a. Several properties were common to the Mr 95,000 polypeptides from both sources: (i) identical molecular weights, (ii) identical gel electrophoresis patterns after limited protease digestion, and (iii) immunological crossreactivity with an IgG fraction directed against the Mr 95,000 polypeptide from phycobilisomes. On the basis of this evidence, a common polypeptide exists in phycobilisomes and thylakoids, and it probably anchors the phycobilisome to the thylakoid membrane. The fluorescence emission overlap of the blue and green polypeptides suggests that they are involved in the transfer of energy from phycobilisomes to thylakoids.Phycobilisomes are organelles on the photosynthetic membrane of red and blue-green algae (cyanobacteria) that function in absorbing light in the wavelength region where chlorophyll absorption is low. Such an extension of the absorption region especially benefits organisms growing under light-limiting conditions. Light absorbed by the phycobiliproteins (phycoerythrin, phycocyanin, and allophycocyanin) is funnelled through a long-wavelength-emitting allophycocyanin to chlorophyll a (reviewed in ref. 1). In cells ofthe red alga Porphyridium cruentum, Duysens (2) and French and Young (3) demonstrated energy transfer from phycoerythrin to chlorophyll. Because the transfer efficiencies from phycobiliproteins to chlorophyll are high (80-90%), it is expected that phycobilisomes have a functional attachment site in close proximity to photosynthetic reaction centers (4). Although phycobilisome attachment molecule(s) have not yet been found, such molecules have been identified for another thylakoid binding complex, the coupling factor (5). Assuming that there are specific attachment molecule(s) in phycobilisomes, we have undertaken a comparison of the polypeptide compositions of isolated phycobilisomes and of thylakoids (free of phycobilisomes) to determine which components are likely to be involved in phycobilisome/thylakoid attachment and energy transfer.The phycobilisome protein composition ofP. cruentum (synonymous with P. purpureum) has been reported (6). As with many other algae (7-9), the phycobilisomes were found to consist of many polypeptides, some ofwhich appeared colored and others noncolored after NaDodSO4/polyacrylamide gel electrophoresis. A pigmented polypeptide (F680) was reported to have a high molecular weight (95,000) and to constitute approximately 1.3% of the phycobilisome protein on the basis of Coomassie blue staining (6). As already reported in a preliminary communication (10), a polypeptide with the same molecular weight and a si...

The dry-composting toilet, which uses neither water nor sewage infrastructure, is a practical solution in areas with inadequate sewage disposal and where water is limited. These systems are becoming increasingly popular and are promoted to sanitize human excreta and to recycle them into fertilizer for nonedible plants, yet there are few data on the safety of this technology. This study analyzed fecal coliform reduction in approximately 90 prefabricated, dry-composting toilets (Sistema Integral de Reciclamiento de Desechos Orgánicos [SIRDOs]) that were installed on the U.S.-Mexico border in Ciudad Juárez, Chihuahua, Mexico. The purpose of this study was to determine fecal coliform reduction over time and the most probable method of this reduction. Biosolid waste samples were collected and analyzed at approximately 3 and 6 months and were classified based on U.S. Environmental Protection Agency standards. Results showed that class A compost (high grade) was present in only 35.8% of SIRDOs after 6 months. The primary mechanism for fecal coliform reduction was found to be desiccation rather than biodegradation. There was a significant correlation (P ‫؍‬ 0.008) between classification rating and percent moisture categories of the biosolid samples: drier samples had a greater proportion of class A samples. Solar exposure was critical for maximal class A biosolid end products (P ‫؍‬ 0.001). This study only addressed fecal coliforms as an indicator organism, and further research is necessary to determine the safety of composting toilets with respect to other pathogenic microorganisms, some of which are more resistant to desiccation.

Abstract. This study identified differences in the epidemiology of Giardia and Cryptosporidium infection for lowincome populations residing on the United States-Mexico border. Participation included 77 households in three communities lacking adequate municipal water and sewage services. The household was the unit of analysis and sampling was from household biosolid waste from newly installed composting toilets. The proportion of households positive for Giardia and Cryptosporidium was high, 82% and 70%, respectively, and this was in contrast to the few households (14%) reporting at least one individual with diarrhea symptoms. This finding indicated that most of the participant families were chronically infected but asymptomatic. In the multivariate analysis, there was a statistically significant protective effect for Cryptosporidium in those households that purified drinking water but not for Giardia. Those households with children less than five years of age were 1.3 times at risk for Giardia infection. Our findings highlighted differences in the transmission mode of these two pathogens and underscore the need for interventions addressing hygiene, water supply, and sanitation.