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

MICAELA B. RUIZ; JUAN M. BUSSO; GABINA V. EGUIZABAL; ABEL G. LOPEZ

Berlin

Conferencia; 5th Annual ISWE Conference, Non-Invasive Hormone Monitoring Conference.; 2015

ISWE

Measuring fecal glucocorticoids have potential to improve wildlife conservation, but there are methodological concerns. Feces require storage methods to avoid steroid degradation by fecal microorganisms. Freezing is recommended; however, it is a costly method under non-controlled environmental conditions. This study aimed at determining if thymol reduces the proliferation of microorganisms in feces from Tamandua tetradactyla and affects hormone measurements. Fresh feces were collected from each animal (n=5), divided into fractions (5.5g each) and evaluated at 0, 24, 48 and 72 h post-excretion. Treatment consisted of an ethanol solution (500 µL; 80% ethanol) of thymol (5mg g-1 feces). Control consisted of 500 µL of the ethanol solution. Additionally, negative control for hormone measurements consisted of samples without ethanol solution. All samples were kept in sealed glass Petri dishes at 22±2ºC. Total aerobic 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 four of the five studied groups of microorganisms, with a significant reduction of up to three orders of magnitude being observed in the colony forming units per gram of feces at 24, 48 and 72 h. By contrast, SFB show no reduction induced by thymol. Unexpectedly, when analyzing the effect of post-excretion time on hormone measurements, treatments show no differences across time periods. More studies should evaluate if feces could be maintained without freezing up to 72h post-excretion. Thymol affected hormone measurements, however, values detected 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 might be useful to control microbial activity in feces from other species; however, other solvents should be evaluated to avoid inaccuracy in hormone measurements.