RATE OF REMOVAL AND POPULATION DYNAMICS OF Candida spp. IN BIOFERTILIZER PRODUCED FROM DAIRY CATTLE WASTE

Dairy farming generates a large amount of waste and an alternative for its correct disposal is its anaerobic biodigestion, generating biogas and biofertilizer. It is important to note that the biofertilizer produced may have microbial load associated to clinical cases, and bacterial pathogens are better characterized than fungal pathogens. To establish the risk of using the biofertilizer, studies on its microbiological safety involving potential fungal pathogens are required. In order to advance the studies involving dairy cattle residue for biofertilizer production, this work proposes to delineate the population and determine the rate of removal of Candida spp. in the affluent and effluent of the biodigester. Between February and March 2018, 5 collections of the Canadian model biodigestor of the experimental farm of EMBRAPA Gado de Leite were carried out. From 10 ml of the collected samples, 0.1 ml was inoculated and disseminated with a Drigalsky loop, in duplicate, in the CHROmagar Candida (Difco) differential and selective culture medium and after the incubation time the direct count plate) of the colonies, the isolation of distinct morphotypes and the calculation of the rate of removal of Candida spp. Microbial quantification at each collection was converted to log10 (log CFU / ml). The Variance Analysis (ANOVA) test and the Tukey test were used to test the populations of Candida spp. in the tributary and effluent. The level established for significance of the tests used was p <0.05. A significant difference (p <0.05) of 0.88 log cycles was observed in the direct quantification of Candida spp. (3.78 log CFU / ml) and effluent (2.90 log CFU / ml) after 30 days of TDH, confirming the importance of anaerobic biodigestion in the elimination of potential pathogens in the effluent used for fertirrigation. In all, 177 Candida spp. were isolated, of which the most present species were C. tropicalis (63), C. albicans (47), C. krusei (37), C. glabrata (22). These isolates show that the process of anaerobic biodigestion requires further studies for the identification and control of potential fungal pathogens present. The death rate of Candida spp. was 1,664 Candida / 100 ml per day and the efficiency of removal of the biodigester turned around 79.2%. In the literature, no studies were found involving death rate and fungal removal efficiency, such as Candida spp., Confirming once again the need for further studies involving fungi in the biodigestion process.