LACTIC ACID BACTERIA AS POTENTIALLY CONTROL AGENTS OF Batrachochytrium dendrobatidis

NIEDERLE, M.V.; ALE, C.E.; ACEVEDO, M.A.; NADER-MACIAS, M.E.F.; TOLEDO, L.F.; PASTERIS, S.E.

Tucumán

Simposio; V SIMPOSIO INTERNACIONAL DE BACTERIAS LACTICAS; 2016

CERELA-CONICET

Chytridiomycosis (CM) is a worldwide emerging infectious disease that produces global amphibian declines in both wild and captive species, some of them endangered, Batrachochytrium dendrobatidis (Bd) being the etiological agent. Nowadays, probiotics represents a novelty approach to prevent CM and include a reduced spectrum of autochthonous skin-microorganisms in which lactic acid bacteria (LAB) are not involved. Moreover, Lithobates catesbeianus-bullfrog (LC) is a Bd carrier that promoted the Bd dissemination. Our research group had informed that LAB are members of the autochthonous microbiota of LC and had demonstrated that some species showed beneficial properties against Red Leg Syndrome-related pathogens. Taking into consideration that LAB could co-evolutioned with Bd and antimicrobial peptides from LC skin, we directed the research to evaluate the capability of the LAB and presumptive LAB microorganisms as potentially control agents of CM. 117 isolates from an LC hatchery including L. lactis CRL 1584 and CRL 1827, E. gallinarum CRL 1826 and LAB (Gram+, catalase-, cocci and bacilli) were tested against Bd CLFT 001 and CLFT 024/02 (isolated in Brazil). The anti-Bd activity was evaluated by co-culture assays: bacteria were previously grown in H broth (1% tryptone + 1% glucose) and later added in a straight line (10 µL, 109 CFU/mL) over H soft agar (0,9%), pre-inoculated with Bd strains (500 µL of 7 days-cultures, O.D.490 nm 0,2). The plates were incubated for 10 days, at 20°C. Bacterial surface properties were also determined by using standardized protocols: autoaggregation (4 h) and hydrophobicity (xylene, ethyl acetate and chloroform). Exopolysaccharides (EPS) production was screened by a qualitative technique in BHI agar + Congo Red. All the LAB/presumptive LAB grew under the Bd conditions. The results indicate that 18.5% of bacteria showed anti-Bd activity, being CLFT 001 the most sensitive (55.55%) with a predominantly weak inhibition (lower growth around the bacterial line). Only 50% of the isolates inhibited the two Bd strains. 66.66% of bacteria inhibited completely the CLFT 024/02 growth (strong inhibition). With respect to the surface characteristics, 11.57% LAB/presumptive LAB were hydrophobic, mainly those isolated from ventral skin. Only 3.15% showed to be autoaggregative at ≤ 2h and 25.26% produced EPS. The results obtained in this work are the first approach to characterize the potentially probiotic of LAB/presumptive LAB isolated from LC skin for their application to prevent CM in situ or during ex situ breeding of threatened amphibian species.