Enhanced production of polygalacturonase in solid-state fermentation: selection of the process conditions, isolation and partial characterization of the enzyme

Abstract

Polygalacturonase (PG) production by Penicillium chrysogenum during solid-state fermentation was accompanied by decomposition of orange peels. A leaching procedure was developed through the selection of solvent, time and intensity of stirring. A maximum PG activity was observed after 48 h peel inoculation. Further cultivation decreased the enzyme activity significantly, up to 60% of the maximum PG activity. During fermentation, a rapid acidification of the solid medium which inhibited the pectinolytic enzyme, was observed. Buffering agents with different pH values and different ionic strengths were examined to identify the most suitable medium to avoid this problem. Buffer addition counteracted acidification and enhanced active protein production, which was observed for all of the applied pH values (6.5-8.0) of the buffering agent. The most satisfactory results were obtained when using the highest pH at 8.0. The protein content and PG activity increased from 3.5 mg/g and 1.09 U/g to 7.7 mg/g and 7.11 U/g during cultivation, with uncontrolled and pH-controlled medium, respectively. Measurements at wide pH and temperature ranges indicated an optimum for PG activity at pH 5.0 and 43°C; however, high thermal stability corresponded to lower temperatures, and a temperature of 37°C is thus recommended. Under these conditions, the operational stability was determined to be t1/2=570 h.

Application and optimization of solid-state fermentation process for enhancing polygalacturonase production by Penicillium expansum

“…Natural pH and 6.0 were found to be suitable for enhancing polygalacturonase production (Figure 2a), which is supported by the finding of Patil et al [3] Zasłona and Trusekhołownia [7] have reported that the most promising production was obtained when the pH was 8.0. But Sethi et al [9] reported that pH 5.0 was optimum for the production of pectinase by Aspergillus terreus NCFT 4269.10.…”

“…Sethi et al [9] and Maller et al [23] have also reported that A. terreus and A. niveus produced pectinase optimally at 4 d of incubation, which is in agreement with current finding in this research. But the maximum polygalacturonase activity was observed after 3 d by using Penicillium variotii [3] and Penicillium chrysogenum [7] , and at 5 d by using Penicillium atrovenetum [24] , respectively. The reason might be that the natural substrate induced the enzyme production at various phase for different strains.…”

“…These advantages achieved special economic interest from those industries with abundance of biomass and agro-industrial residues [6,7] , in particular fruits processing industry. Various agro-industrial residues such as mango peel [8] , banana peel [9] , orange peel [10] , grape pomace [11] , coffee beans [12] , papaya peel [13] , wheat bran [4] and apple pomace [14] have been considered as preferable SSF substrates (carbon and energy sources) to produce polygalacturonase due to their availability and low-cost.…”

“…[16] . In recent years, Penicillium, as a genus of ascomycetous fungi, has demonstrated great potential of producing polygalacturonase and received extensive attention in polygalacturonase biosynthesis [7] . This study attempted to apply Penicillium expansum 3.5425 in SSF with wheat bran and apple pomace as carbon substrates to produce polygalacturonases.…”

Purification and characterization of polygalacturonase from Aspergillus fumigatus MTCC 2584 and elucidating its application in retting of Crotalaria juncea fiber

“…The pH optima of purified PGs determines its possible application like fruit juice clarification, retting of natural fibers etc. It has been observed that most of the fungal PGs have pH optima 3–6 (Patil et al 2012 ; Yadav et al 2012 ; Kant et al 2013 ; Martins et al 2013 ; Castruita-Domínguez et al 2014 ; Ortega et al 2014 ; Chen et al 2014 ; Zhou et al 2015 ; Zaslona and Trusek-Holownia 2015 ; Pan et al 2015 ).…”