Abstract

Sonagnon H. S. Kouhoundé, Marius K. Somda, Innocent Y. Bokossa, Lamine S. BabaMoussa, Frank Delvigne, Alfred S. Traore and Philippe Thonart

Polygalacturonases (PGs) are known for their application in the clarification and extraction of fruit juice and wine. In this study, PG activity was investigated in 125 strains of microorganisms comprising of bacteria and yeast previously isolated from the microbiota of fermented cassava. In order to investigate PG activity, these purified strains were grown on agar media containing apple pectin or polygalacturonic acid (PGA) at 0.5 to 1%. A screening test performed at the end of cultivation revealed PG activity in each producing strain, allowed the detection of Saccharomyces cerevisiae KSY4, Saccharomyces cerevisiae KSY5, Saccharomyces cerevisiae KSY9, Bacillus sp. KSB30 and Bacillus sp. KSB32, which were identified using phenotypic test. Screening assays carried out on Petri dishes showed limitations, the depolymerization reactions were carried out using two substrates (pectin and PGA) at different concentrations with each extract from strain isolated which exhibited PG activity. The results show that at pH 5 at 30°C/25 min, Bacillus sp. KSB32 exhibited a PG production of 2.33 U/ml on pectin (5 g/l) versus 1.35 U/ml on PGA. An increase in PG production, reaching 3.24 U/ml was concomitant with the pectin concentration. These results conclude that PG activity is function of nature and substrate concentration