Inhibitory action of thymol in fecal microbial activity of Tamandua tetradactyla and its effect on glucocorticoid metabolite measurements

RUIZ MICAELA BELEN; BUSSO JM; EGUIZABAL GABINA; LOPEZ ABEL GERARDO

Berlín

Conferencia; 5th International Society of Wildlife Endocrinology; 2015

Measuring fecal glucocorticoidshave potential to improve wildlife conservation, but there are methodologicalconcerns. Feces require storage methods to avoid steroiddegradation by fecal microorganisms. Freezing is recommended; however, it is acostly method under non-controlled environmental conditions. This study aimedat determining if thymol reduces the proliferation of microorganisms in fecesfrom Tamandua tetradactyla and affects hormonemeasurements. Fresh feces were collected from each animal (n=5), divided intofractions (5.5g each) and kept in sealed glass Petri dishes at 22±2ºC. Treatmentconsisted of a thymol solution (5mg g-1 feces; 500 µL; 80% ethanol),whereas control consisted of 500 µL of the ethanol solution. Additionally,negative control for hormone measurements consisted of samples without ethanolsolution. All samples were evaluated at 0, 24, 48 and 72 h post-excretion. Totalaerobic and anaerobic heterotrophic mesophilic bacteria, spore-forming bacteria(SFB), total coliforms, mould and yeast were counted. For hormone analysis, samples(0.5g) were frozen and then dried (60ºC).The analysis of variance indicated that thymol had an inhibitory effect on fourof the five studied groups of microorganisms, with a significantreduction of up to three orders of magnitude being observed in the colonyforming units per gram of feces at 24, 48 and 72 h. By contrast, SFB show noreduction induced by thymol. Unexpectedly, when analyzing the effect of post-excretiontime on hormone measurements, treatments show no differences across timeperiods. More studies should evaluate if feces could be maintained withoutfreezing up to 72h post-excretion. Thymol affected hormone measurements, however,values were more similar to negative control than control (negative control: 1251±118> thymol: 986±98 > control: 792±77 ng/g dry feces; p=0.05). Thymol mightbe useful to control microbial activity in feces from other species; however,other solvents should be evaluated to avoid inaccuracy in hormone measurements.