CULTURE MEDIA PERFORMANCE ON THE DETECTION OF ACTINOMYCETES FROM COMPOSTS

This study evaluated the performance of six culture media for the detection of actinomycetes present in composts of agro-industrial wastes. The composts were produced with orange wastes, olive marc and grass clippings, in the proportion of 2:1:1 in volume. Two compost piles were built with different ventilation systems: one with forced ventilation and the other with mechanical turning and natural ventilation. In order to quantify the population of actinomycetes, different growth media containing antibiotics were tested, and also one culture medium containing only half of the concentration of the Plate Count Agar (½ PCA). The incubation took place at two temperatures: 25° and 55°C. The population of actinomycetes was higher when incubated at 55°C and when the samples were inoculated in ½ PCA culture medium. Thus, the antibiotics showed no beneficial effect in the tested culture media. The results suggest the use of the ½ PCA culture medium as the most suitable in order to count actinomycete populations in these compost samples. This medium was also less expensive than the one that showed the fastest bacterial growth.