Optimisation of alkaline pretreatment conditions of orange and plantain peels for polygalacturonase production by Aspergillus awamori CICC 2040

O.E Adedeji,O.O Ezekiel

doi:10.4314/njb.v37i2.2

Abstract

This study investigated the optimisation of alkaline pretreatment of orange and plantain peels for polygalacturonase (PG) production by Aspergillus awamori CICC 2040 using response surface methodology. The factors evaluated were particle size, PS (< 0.4250, 0.4250 < PS < 0.8025 and 0.8025 < PS < 1.1800 mm), NaOH molarity (0.010, 0.055, and 0.100 M), and time (1.0, 6.5, and 12.0 h). These factors were interacted to determine the most suitable combinations for maximum polygalacturonase activity (MPA). The pretreated orange and plantain peel powders were inoculated with 106 spores/mL Aspergillus awamori CICC 2040 was incubated at 28 oC for 5 days, and crude PG was extracted and its activity determined. The alkaline pretreatment combinations that gave MPA were <0.4250 mm, 0.100 M, and 1.0 h, and 0.8025 < PS < 1.1800 mm, 0.010 M, and 1.0 h for orange and plantain peel powders, respectively. The MPA obtained from the pretreated orange and plantain peel powders were 38.46 and 38.82 U/mL, respectively. Optimised alkaline pretreatment conditions of the orange and plantain peels for MPA, produced by Aspergillus awamori CICC 2040, were established. Keywords: Aspergillus awamori CICC 2040, Peel, Optimisation, Polygalacturonase, Pretreatment

Highlights

Polygalacturonase (PG) (E.C. 3.2.1.15) is a pectinase involved in the degradation of polygalacturonan in plant’s cell walls through the hydrolytic breakdown of glycosidic bonds that bind galacturonic acid moieties (Heerd et al, 2012)
For Orange peel powder (OPP), a maximum PG activity of 38.46 unit of activity per mL (U/mL) was obtained at Run 3 i.e. < 0.425 mm, 0.1 M NaOH and 1 h
A maximum PG activity of 38.82 U/mL was obtained from Run 2 i.e. 0.8025 < PS < 1.1800 mm, 0.01 M, and 1 h for plantain peel powder (PPP)

Summary

Introduction

Polygalacturonase (PG) (E.C. 3.2.1.15) is a pectinase involved in the degradation of polygalacturonan in plant’s cell walls through the hydrolytic breakdown of glycosidic bonds that bind galacturonic acid moieties (Heerd et al, 2012). There has been considerable interest in the use of food wastes and agricultural residues as substrates for the production of bio-products, both from the economic and environmental viewpoints. The utilisation of agricultural residues is increasing due to the high cost of traditional feedstocks (Wadhwa et al, 2015). The environmental concerns of un-utilised wastes stem from the generation of hazardous materials that are released to nature as a result of their degradation. This results in environmental pollution, which has both short and long term effects (Obi et al, 2016).

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Conclusion