Relations fecal coliforms/ fecal Streptococci as indicators of the origin of fecal pollution in urban and rural water bodies of Temuco, Chile

The presence of alloctone bacteria is considered as one of the more important biological pollutants of water bodies, existing one close relation between the fecal contamination indicators and the existence of urban and industrial zones. In the present study we utilized indicators of fecal contamination (coliforms and streptococci) and the coliform/streptococci index (FC/FE) for determine the origin of fecal pollution in two water bodies of Temuco, Northern Campus at north surrounding of Temuco, and Rucamanque source that is located in a rural zone. It utilized the multiple assays number for obtain the bacteria more probable number in 100 ml of water sample. It was done the correlations between microbiological indicators and physic-chemical variables. The results indicate that both sites have low fecal contamination. It was reported important correlation between fecal coliforms, temperature and pH, but negative correlations with dissolved oxygen. The index (FC/FE) was correlated only with dissolved oxygen. The temperature would have an important regulator role in the coliform growth, whereas the fecal streptococci have high densities at low values of temperature, conductivity and dissolved oxygen. The origin of microbiological pollution was related with the antrophogenic intervention in both studied sited, human origin in Northern Campus, and mixed origin in Rucamanque source. It was suggest the use of index as first approach for identify the origin of fecal pollution. La presencia de bacterias aloctonas es considerada uno de los contaminantes biologicos mas importantes de los sistemas acuaticos, existiendo una estrecha relacion entre los indicadores de contaminacion fecal y la existencia de centros urbanos e industriales. Se utilizaron indicadores de contaminacion fecal (coliformes y estreptococos fecales), y el indice coliformes/estreptococos fecales para determinar la fuente de contaminacion fecal en dos cuerpos de agua de la comuna de Temuco, Laguna Campus Norte, situada en zona urbana y bocatoma Rucamanque, ubicada en un sitio rural. Se utilizo la tecnica de tubos multiples para obtener el numero mas probable de bacterias en 100 ml de agua. Se efectuaron correlaciones entre los indicadores microbiologicos y variables fisicoquimicas. Los resultados indican que ambos sitios presentaron baja contaminacion fecal. Se reportan importantes correlaciones entre coliformes fecales, temperatura y pH. Los estreptococos fecales exhibieron altas correlaciones con la temperatura y pH, pero negativas con el oxigeno disuelto. El indice CF/FE se correlaciono unicamente con el oxigeno disuelto. La temperatura jugaria un rol regulador en el crecimiento de los coliformes, en cambio los FE, presentan mayores densidades a menores valores de temperatura, pH, conductividad y oxigeno disuelto. La fuente de contaminacion microbiologica se relaciono con la intervencion antropica presente en los sitios, origen humano en laguna Campus Norte y origen mixto en bocatoma Rucamanque. Se recomienda el uso del indice como primera aproximacion para identificar el origen de la contaminacion fecal.