SCREENING OF BIOPOLYMER PRODUCTION BY NATURE FUNGAL ISOLATES FROM MANAUS (BRAZIL)

FARIÑA JI; CAMELINI CM; FISCHBORN A; BENTOLILA L; DE JESÚS MA; SALES-CAMPOS C

Bs. As.

Congreso; II Workshop on Bio-degradable Polymers and Biocomposites III Workshop BIOPURFIL, Bio-based Polyurethane Composites with Natural Fillers; 2015

INTEMA (UNMP) ITPN (UBA)

INTRODUCTION. Over the latest years, filamentous fungi have been efficiently employed in different environmentally valuable strategies such asbioremediation of soils and effluents, lignin and recalcitrant substances degradation, or for the production of fungal biomass and metabolites of commercial interest. Lignocellulolytic fungi can frequently exhibit the abilityto produce exopolysaccharides (EPSs), which may play a role during biodegradation. During the last decades the search for new biopolymers with potential applicationat industrial, environmental, medical or pharmaceutical level has awaken a growing interest in the international scientific community. Brazilian megadiversity, and especially the Amazonas region, offers natural resources that have not yet been exploited or even explored. In this context, fungal diversity represents a genetic heritage that deserves attention and preservation for a better and sustainable exploitation. This latter goal could be achieved by the use of microbiotechnology tools which would allow us to preserve and cultivate selected fungi under laboratory conditions, as well as to obtain desired fungal products without devastating Nature mycoflora.Therefore, in this work, the ability of fungal specimens from Manaus (Amazonas) was evaluated at shake-flask scale for the production of EPSs under submerged culture conditions. MATERIALS AND METHODS. Nine different fungal strains isolated in Manaus (AM) including genera such as Boletus, Flammulina, Lentinus, Pleurotus, Schizophyllum and Sclerotium, were tested on their ability to produce EPSs when cultured in liquid medium. Results were comparatively assessed with those from the high EPS-producer S. rolfsii ATCC 201126 (isolated from rotten red pepper). Production of EPSs was tested by culturing in 250-mL Erlenmeyerflasks containing 50 mL of MOPT production medium, in g/L: sacarosa, 150; NaNO3, 2.25; K2HPO4·3H2O, 2; yeast extract, 1; citric acid·H2O, 0.7; KCl, 0.5; MgSO4·7H2O, 0.5; FeSO4·7H2O, 0.05; initial pH 4.5. Production of EPS was tested after cultivation at 30ºC and 220 rpm for 72 h. Inocula were prepared from active cultures on Czapek malt agar plates by homogenization of mycelium-covered plugs. For every isolate, EPS production and mycelial growth were measured by gravimetric estimation. After EPS recovery by filtration, residual sugars were also determined in the filtrate by the DNSA method. RESULTS AND DISCUSSION. Most of the tested isolates showed good growth in MOPT culture medium. The highest biomassvalues (27.2, 37.8 and 31.5 g/L) corresponded to the four Sclerotium tested isolates, including the control strain S. rolfsii ATCC 201126 (35.5 g/L). With regard to EPS production, again the Sclerotium strains led to the highest values (25.5-40.0 g EPS/L) being S. rolfsii 2745 (from rotten tomato) the most promising EPS-producer. For the other fungi, mycelial growth was lower and ranged between 3.6 and 6.8 g/L, whilst EPS production reached values of 4.1-5.5 g/L. Consumption of C-source was low, as usually found for S. rolfsii ATCC 201126, but in the case of the S. rolfsii 2745, the higher utilization of sugars may related to the highest EPS production obtained. These results thus confirmed the ability of different fungal specimens from Amazonas to produce EPSs, but particularly highlighted the marked ability of Sclerotium species for biopolymer production.