Prospecting of new isolates producers of pectinolitic enzymes were performed with cultivation of substrates of rice, soybean and corn bran. Pectinolitic enzymes were observed in cultures of the isolates NFC 1, NFC 2, NFC 4, NFC 5 and NFC 6 identified as belonging to the genus Aspergillus sp. Isolates NFR 1, NFR 2 and NFS1 were identified as belonging to the genus Rhizopus and NFC 3 belonging to the genus Cladosporium; however, pectinolitic enzymes production was not observed. The polygalacturonase (PG) production in submerged fermentation of Aspergillus NFC 2 in culture medium proposed (SM) at 28 and 37°C was quantified by agar diffusion and spectrophotometric methods. The highest PG production was obtained at 28°C by greater formation of halo degradation pectin and the activity measured by spectrophotometric methods. The activity of PG obtained was 7 U.mL-1 with volumetric productivity greater in the first 24 h of fermentation both at 28 and 37°C. A decrease in PG synthesis occurred after 48 to 120 h. The study allowed, by means of rapid microbiological tests, the selection of new isolates fungi for PG production and the definition of crucial stages for cultivation in liquid medium.
Key words: Filamentous fungi, Aspergillus sp, pectinolytic enzymes, polygalacturonase, submerged fermentation.
ANOVA, Analysis of variance; DNA, deoxyribonucleic acid; DNS, dinitrosalicylic acid; NFC, new fungal strain of corn; NFR, new fungal strain of rice; NFS, new fungal strain of soy; PCR, polymerase chain reaction; PDA, potato dextrose agar; PG, polygalacturonase; pH, hydrogen potential; PL, pectin lyase; PME, pectin metilesterase; SM, culture medium proposed.