This study investigated strain-dependent variability in Escherichia coli survival in soil, and strain-dependent responses to variations in some soil conditions. Collections of E. coli were isolated from swine manure slurry, and from manured soil following 6 days of incubation in the laboratory. The bacteria were fingerprinted by enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR). During the course of the incubation the composition of the E. coli community changed dramatically suggesting that E. coli phylotypes, distinguishable by ERIC-PCR fingerprinting, varied significantly in their ability to survive in soil under these conditions. A representative isolate from one ERIC group which increased in abundance in soil (designated strain C279) and one which decreased (designated strain C278) were chosen for comparison. These strains persisted comparatively when inoculated into loam soil. However, when added into a loam soil or a sandy soil supplemented with 10% (v/v) swine manure slurry, strain C279 increased in abundance 10-fold, whereas strain C278 did not. At 4 degrees C, or in a clay loam soil, manure slurry did not support the growth of strain C279. These results indicate that the community composition of E. coli populations in manured soils can be very dynamic, and that strains able to proliferate in manured soils can have a selective advantage.

The potential exists for natural or synthetic hormonal chemicals present in agricultural fertilizers to be transferred to adjacent aquatic environments in order to alter endocrine function in exposed wildlife. Recombinant yeast and mammalian cell line (BG1Luc4E2) assays were used to screen crude organic extracts of municipal biosolids and animal manures for estrogen-, androgen-, and progesterone receptor gene transcription activities. Of the biosolid extracts, those samples that had undergone aerobic digestion had no or minimal estrogen- and no androgen receptor gene transcription activities. In contrast, those biosolid samples that had undergone anaerobic digestion had much higher estrogen- and, for all but one site, androgen receptor gene transcription activities. Extracts prepared from animal manure samples had variable levels of androgen- and estrogen receptor gene transcription activities, which may be related to the type, sex, age, and reproductive status of the animals. The diet and treatment of animals with hormone implants also appeared to be factors influencing hormone activity in animal manure. Progesterone receptor gene transcription activity was observed for only one chicken litter sample. Overall, results of this study suggest that in vitro bioassays can be used to survey and detect hormone activity in municipal biosolids and animal manures. Furthermore, results of these assays can be used to develop practices that will minimize the potential environmental endocrine-disrupting effects of these substances.

No abstract

This study examined the effect of chicken, liquid swine, and solid cattle manures on verticillium wilt and potato scab incidence at two commercial farms near Alliston, Ontario. The manures (chicken, 66 tlha; swine, 55 hUha; cattle, 100 tlha) were spread in the spring of 1996 and incorporated with a Rototiller to a depth of 15 cm. Survival of Verticillium dahliae microsclerotia (MS) was determined by burying nylon mesh bags containing MS in the plots. After 4 weeks, the MS were plated on agar medium. Soil samples collected after incorporation of manures were brought back to the laboratory and used for concurrent laboratory experiments. Ten-gram amounts of soil were placed into test tubes, bags of MS buried in the soil, and survival measured under controlled conditions. Potatoes were planted in the field I month after amendment. Potatoes were planted in 1997 and 1998 without any further treatment. Verticillium wilt incidence was determined by isolation of V. dahliae from petioles. Scab incidence was determined from visual estimation of lesion coverage on tubers. Changes in soil chemistry, in soil microbiology, and in populations of plant pathogenic nematodes were also determined. Chicken manure reduced scab and wilt incidence and nematodes to near zero levels at both sites. Swine manure reduced scab incidence at both sites but reduced wilt and nematode populations at one site only. Cattle manure application caused a small reduction in wilt at one site. Disease incidence in the second crop was similar for all treatments except for swine manure at one site where a lower scab incidence was observed and chicken manure at both sites where wilt incidence remainded below that in untreated plots. Scab incidence in the third crop was reduced at one site treated with swine manure, but one of the chicken manure treated plots had a higher scab incidence than the untreated plot. The viability of MS was similar for identical treatments in the field and laboratory assay and predicted which treatments decreased verticillium wilt. Reductions in viability of MS were found to be manure and soil specific.Resume: La presente etude avait pour but d'examiner, sur deux fermes commerciales pres d'Alliston (Ontario), l'effet du fumier de poulet, du lisier de pore et du fumier de vache sur la verticilliose et sur la gale de la pomme de terre.Les fumures (poulet, 66 t/ha; pore, 55 hUha; vache, 1 ()() tlha) ont ete repandues au printemps de 1996 et incorporees a une profondeur de 15 cm a !'aide d'un motoculteur. La survie des microsclerotes (MS) du Verticillium dahliae a ete determinee en enterrant, dans les parcelles, des sacs de tulle de nylon contenant des MS. Apres 4 semaines, les MS furent placees sur un milieu gelose. En parallele, des echantillons de sol recoltes apres !'incorporation des fumures furent apportes au laboratoire pour d'autres experiences. Des sacs de MS furent enfouis dans des enchantillons de 10 g de sol en eprouvettes et la survie fut mesuree en conditions controlees. Des pommes de terre furent plantees dans le champ un...

No abstract