Isolation of Cellulolytic and Hemicellulolytic Bacterias from an Argentinean Termite

FELICE, F; BEN GERRERO, E; SALVADOR, R.; CAMPOS, E.; ARNEODO, J. D.; TALIA, P.

Córdoba

Congreso; XI Congreso Argentino de Microbiología General; 2015

In the last few years, the production of lignocellulosic bioethanol has been gaining attention in many science and engineering disciplines.This is mainly due to the climate change, the need to reduce emissions of greenhouse gases and the variability of petroleum cost.Many invertebrates have the capability to degrade cellulose. In higher termites, lignocellulose digestion is performed by endogenous and bacterial endosymbiont bacterial enzymes present in the digestive tract. In this context, our group has been working to isolate microorganisms that degrade cellulose efficiently.The objectives of this study are to isolate and evaluate bacteria with cellulolytic activity present in Argentinean termite guts.Adults Nasutitermes aquilinus (Isoptera) were sterilized superficially with 70% ethanol. Then, the insect guts were extracted and the rest of the body was discarded. Serial dilutions of termite guts were incubated with minimal media (MM) and a piece of filter paper (Whatman N°1; 2.5 cm x 1.0 cm), as the only carbon source for 10 days at 37°C, in order to promote growth of microorganisms with the ability to use cellulose. A total of 100 µL of each liquid culture was streaked out on agar plates containing MM supplemented with 1% carboxymethylcelullose (CMC) and 0.05% trypan blue (TB), 1% xylan and 0.005% TB and 0.001% 4-Methylumbelliferyl β- D -glucopyranoside(MUG). After 24 h of incubation at 37°C and successive re-streaking, 10 bacterial isolates were obtained. Positive colonies were determined by a clear zone around the colony on all media containing the TB. The cellulolytic and hemicellulolytic activities of each isolate were evaluated with dinitrosalicilic acid assays (DNA) andparanitrofenyl-β-D-glucopyranoside(pNPβG). To identify bacterial genera, we extracted total DNA from each positive colony and then amplified, cloned and sequenced the partial 16S rRNA gene.Stenotrophomonas, Cellulomonas, Afipia, Cohnella, Staphylococcus and Paenibacillus were identified by sequence analysis of the 16S rRNA.The highest endoglucanase and xylanase activities were observed in Cellulomonas (Endoglucanase: 3.127 ± 0.100UI/g; Xylanase: 1.419 ± 0.031 UI/g) and Cohnella (Endoglucanase: 3.042 ± 0.371 UI/g; Xylanase: 1.559 ± 0.017 UI/g).The evaluation of bacterial isolates obtained from N. aquilinus gut extracts showed that this guts havetheir high cellulolytic enzyme production and their ability to degrade cellulose and hemicellulose. Therefore, these extracts bacteria could be auseful tool to degrade lignocellulosic biomass into simple components for bioethanol production.