Polygalacturonase production enhancement by Piriformospora indica from sugar beet pulp under submerged fermentation using surface methodology

This study proposed a novel and cost-effective approach to enhance and optimize the polygalacturonase from P. indica. In current investigation, the impact of ammonium sulfate, sugar beet pulp (SBP) and glucose as variables on induction of polygalacturonase from P. indica was optimized using the central composite design (CCD) of response surface methodology (RSM) under SmF. Additionally, partial polygalacturonase purification and in situ analysis were performed. The optimal reaction conditions, which resulted in the highest enzyme activity were observed as the following conditions: ammonium sulfate (4 g/L), SBP (20 g/L), glucose (60 g/L). Under the optimized condition, the maximum enzyme activity reached to 19.4 U/ml (127 U/mg) which increased by 5.84 times compared to non-optimized conditions. The partial purified polygalacturonase molecular weight was estimated 60 KDa. In line with the bioinformatic analysis, exo-polygalacturonase sequence of P. indica showed similarity with Rhizoctonia solani′s and Thanateporus cucumeris. These results indicated that SBP act as a cheap and suitable inducer of polygalacturonase production by P. indica in a submerged cultivation. The outcome of this study will be useful for industries to decrease environmental pollution with cost-effective approaches.

OPTIMISATION OF MICROWAVE PRETREATMENT CONDITIONS OF ORANGE AND PLANTAIN PEELS FOR POLYGALACTURONASE PRODUCTION BY ASPERGILLUS AWAMORI CICC 2040

This study investigated the optimisation of microwave pretreatment of orange and plantain peels for polygalacturonase (PG) production, by Aspergillus awamori CICC 2040, using response surface methodology. The microwave pretreatment factors interacted were particle size (PS) (<0.4250, 0.4250<PS<0.8025, and 0.8025<PS<1.1800 mm), microwave power (240, 480 and 720 W) and time (2.50, 6.25, and 10.00 min.). These factors were interacted to determine combinations for maximum polygalacturonase activity (MPA). Pretreated orange and plantain peel powders were inoculated with 106 spores/mL Aspergillus awamori CICC 2040, incubated at 28oC for 5 days, and crude polygalacturonase was extracted and its activity determined. Same microwave pretreatment combination, 0.8025<PS<1.1800 mm, 720 W and 10.00 min, gave MPA for orange and plantain peels. The MPA from orange and plantain peels was 26.21 and 26.72 U/mL, respectively. F and p values obtained for orange peel powder were 35.42 and 0.00, respectively while those obtained for plantain peel powder were 5.71 and 0.006, respectively. R2 and R2 (adjusted) of 96.96 and 94.22%, respectively were obtained for PG activity produced using orange peel powder while 90.71 and 79.04% were recorded for PG activity produced using plantain peel powder. Optimised microwave pretreatment conditions of orange and plantain peels for MPA from Aspergillus awamori CICC 2040 were established. Keywords: Aspergillus awamori, Fruit peel, Microwave, Optimisation, Polygalacturonase, Pretreatment,

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

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

An analysis of exo-polygalacturonase bioprocess in submerged and solid-state fermentation by Pleurotus ostreatus using pomelo peel powder as carbon source

Background As there has been an increasing trend in the effective utilization of plant and crop residues for microbial transformation into a desired product, an attempt was made to compare of exo-polygalacturonase production using logistic and Luedeking-Piret kinetic model by Pleurotus ostreatus in submerged (smf) or solid-state fermentation (ssf) using pomelo peel powder, an agro-forestry residue as carbon substrate. Results Cultures grown in submerged fermentation produced a peak of exo-polygalacturonase activity as 6160 Ul-1 on the 4th day of culture as compared with 2410 Ul-1 on the 5th day of fermentation by solid-state fermentation. The enzyme yield coefficient (YE/X) is of higher value in smf vs. ssf system (YE/X = 1.05 × 103 vs. 0.622 × 103) indicating the more efficient product yield in smf as compared with ssf. The plots derived fromλ versusζ clearly demonstrate that the secondary product destruction is higher in smf than in ssf. Conclusion P. ostreatus performs much better in submerged fermentation as compared with solid-state fermentation in respect to exo-polygalacturonase production although ssf technique produced a more thermo-stable exo-polygalacturonase in crude extract, which is highly desirable in various industrial applications.

Evaluation of coffee pulp as substrate for polygalacturonase production in solid state fermentation

The purpose of this research is to evaluate the coffee pulp, a by-product of coffee processing, as substrate for polygalacturonase production by solid state fermentation. In addition, it is a way to take advantage of the coffee pulp. Characterization of the coffee pulp revealed a high content of nutrients for fungi growth, such as reducing sugars (5.4% of dry pulp), proteins (9.4% of dry pulp), pectins (20.5% of dry pulp), which are inducers of pectic hydrolases production and source of carbon after degradation, and caffeine (1.4% of dry pulp), among others. The characterization of the cell-wall of coffee pulp revealed, after polysaccharides fractionation, the content in cell-wall pectins (25.5%), hemicelluloses (11.5%) and cellulosic residue (44%). A strain of Aspergillus niger, called van Thiegem, has been selected as a good producer of polygalacturonases (60 U/ml) using the coffee pulp as the growth substrate. During fermentation, reducing sugars, caffeine and phenolic compounds were consumed till almost exhaustion. A partial characterization of the polygalacturonase using high methoxyl pectin as substrate indicates an optimal pH of 4.0 and 45oC as optimal temperature, which are good values for the use of the enzyme in vegetable processing, including coffee processing.