Production of Polygalacturonases by Aspergillus section Nigri Strains in a Fixed Bed Reactor

Abstract

Polygalacturonases (PG) are pectinolytic enzymes that have technological, functional and biological applications in food processing, fruit ripening and plant-fungus interactions, respectively. In the present, a microtitre plate methodology was used for rapid screening of 61 isolates of fungi from Aspergillus section Nigri to assess production of endo- and exo-PG. Studies of scale-up were carried out in a fixed bed reactor operated under different parameters using the best producer strain immobilised in orange peels. Four experiments were conducted under the following conditions: the immobilised cells without aeration; immobilised cells with aeration; immobilised cells with aeration and added pectin; and free cells with aeration. The fermentation was performed for 168 h with removal of sample every 24 h. Aspergillus niger strain URM 5162 showed the highest PG production. The results obtained indicated that the maximum endo- and exo-PG activities (1.18 U·mL−1 and 4.11 U·mL−1, respectively) were obtained when the reactor was operating without aeration. The microtitre plate method is a simple way to screen fungal isolates for PG activity detection. The fixed bed reactor with orange peel support and using A. niger URM 5162 is a promising process for PG production at the industrial level.

Optimization of phytase production by Aspergillus japonicus Saito URM 5633 using cassava bast as substrate in solid state fermentation

“…Screening is often the first step to select microorganisms with characteristics intended for Industrial applications, which allows the characterization and selection of fungal strains with optimal enzyme production (Maciel et al, 2013).…”

Pectinolytic complex production by Aspergillus niger URM 4645 using yellow passion fruit peels in solid state fermentation

“…This allows for the characterization and selection of fungal strains with optimum enzyme production. In addition, the information obtained adds value to these microbial resources preserved in culture collections (Maciel et al, 2013).…”

“…Moreover, Maller et al (2011) concluded that agro-industrial residues, such as orange and lemon peels, induced production of high levels of PG by A. niveus. The use of orange peels can be highly economical at the industrial scale for PG production (Maciel et al, 2013). A. niger URM 4645, when cultured using yellow passion fruit peels without the addition of nutrient solution, produced endo-PG, exo-PG, PL, and PE.…”

“…Pectinases or pectinolytic enzymes are naturally produced by plants, filamentous fungi, bacteria, and yeasts (Maciel et al, 2013). Conversion of pectin to soluble sugars is possible through enzymatic reactions catalyzed by pectinolytic enzymes that are common in fungi, such as pectin lyase (PL) (EC 4.2.1.10), pectin methylesterase (PE) (EC 3.2.1.11), and polygalacturonases (PG) (EC 3.2.1.15) (Holck et al, 2011).…”

“…The microbial production of pectinolytic enzymes can be achieved by solid state fermentation (SSF) or submerged fermentation (SMF) (Maciel et al, 2013). Agroindustrial residues or wastes are generally considered suitable substrates for enzyme production by SSF (Pandey, 2003;Patil and Dayanand, 2006).…”