Production and chromatographic behaviour of polygalacturonase from Pleurotus ostreatus on immobilized metal chelates

Yellow laccase produced by Trametes versicolor K1 on tomato waste: A comparative study with the blue one produced on semi-synthetic medium

Laccase production by fungal growth on agrifood waste is still poorly studied. Trametes versicolor K1 isolated from palm bark produced a yellow non glycosylated laccase from tomato waste based medium (TMT) and a blue glycosylated laccase on glucose medium (GLU). Lignocellulosic biomass, such as pinecones (PIN), palm leaves (PLM), olive pomace (OLV), and alfa stems (ALF) have also been used as growth medium for T. versicolor K1. In these conditions, very low or no laccase production was observed. When peptone was supplied in TMT medium, the laccase activity increased from 4170 U/L to 8618 U/L. By increasing the culture volume up to 1 L, laccase production on TMT was 9929 U/L. The yellow laccase (TmtLac) was purified from the supernatant TMT medium and has shown similar characteristics with the blue laccase (GluLac) purified from the GLU medium. Their apparent protein size was 63 kDa. Catalytic activities of the yellow form were not very different from those of the blue form, but specific activity of the purified yellow laccase produced on tomato waste was much higher. The K_m and V_m values for four substrates, ABTS, DMP, guaiacol, and pyrogallol were almost similar for both isoenzymes. The optimum pH and temperature were respectively 4.0 and 50 °C. Although the level of glycosylation is clearly different, the thermostability of TmtLac and GluLac are quite similar. TmtLac is even slightly more tolerant at 60 °C for 24 h than GluLac. Moreover TmtLac showed greater stability at alkaline pH after 24 h compared to that of GluLac.We demonstrate that activity of the yellow TmtLac is not significantly affected compared to the blue laccase and that tomato waste is a simple and interesting lignocellulosic substrate to the laccase producer Trametes sp.

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 (Y_E/X) is of higher value in smf vs. ssf system (Y_E/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.

Purification and Partial Characterization of Peroxidases from Three Food Waste By-Products: Broad Bean Pods, Pea Pods, and Artichoke Stems

In this study, peroxidases (PODs) from three waste by-products: broad bean pods (BBP), pea pods (PP), and artichoke stems (ARS) were purified and their optimal conditions were determined for the first time. The purification process resulted in 4.32, 7.21, and 8.9% of POD recoveries for PP, ARS, and BBP, respectively. They were purified 2.12-, 32.97-, and 10-fold with specific activities of 27.26, 266.43, and 27 U/mg of protein, respectively. Analysis of their optimal conditions showed that POD purified from BBP and PP exhibited the highest activity at 60 °C temperature and pH 6 and 8 with strong affinity with catechol substrate (Km of 0.356 and 0.189 mM; Vmax of 0.08 and 0.041 μM/min for BBP and PP, respectively). The highest activity of ARS POD was obtained under the following conditions: temperature at 50 °C, pH from 6 to 8, and guaiacol as substrate (Km 0.375 mM; Vmax 0.012 μM/min). Apart from giving the opportunity for recycling the food industry wastes, the studied waste by-products could represent an alternative source of PODs that could find several applications in the biotechnological, chemical, and food industries.

Multiple Parameter Optimizations for Enhanced Biosynthesis of Exo-polygalacturonase Enzyme and its Application in Fruit Juice Clarification

The present study investigated the potential of several indigenous fungal strains to produce industrially important exo-polygalacturonase (exo-PG) utilizing locally available agro-industrial wastes in solid-state fermentation (SSF). Amongst various substrates employed, wheat bran supported the highest biosynthesis of exo-PG. Different process variables such as, fermentation duration, moisture level, pH and temperature were optimized using one-variable-at-a-time (OVAT) statistical approach. Results revealed that an initial medium pH of 3.0 at 35 °C together with MnSO4, glycine and pectin have progressive influence on exo-PG synthesis by P. notatum, while C. versicolor displayed utmost enzyme activity at pH 5.0, temperature 30 °C, moisture 50 % using CaCO3, (NH4)2SO4, and lactose as nutritional sources. The enzymatic cocktail treatment achieved a significantly improved clarity by reducing the turbidities, viscosities and absorbance’s of three fruit juices. Scaling up of various fermentation parameters might have potential to produce enhanced activities of exo-PG for different industrial sectors, particularly in food industry.

Optimization of production and reaction conditions of polygalacturonase from Byssochlamys fulva

In the present study, the optimization of production and reaction conditions of polygalacturonase produced by a fungus Byssochlamys fulva MTCC 505 was achieved. The production of polygalacturonase with a considerable activity of 1.28 IU/ml was found when the culture was shaken at 30°C for 5 days in 100 ml of medium containing (w/v) 10 g/l pectin, 2 g/l NaNO₃, 1 g/l KH₂PO₄, 0.5 g/l KCl, 0.5 g/l MgSO₄. 7H₂O, 0.001 g/l FeSO₄. 7H₂O, 0.001 g/l CaCl₂. The best carbon and nitrogen source for this enzyme were pectin (1%) and Ca(NO₃)₂ (0.1%), respectively. The enzyme gave maximum activity at incubation time of 72 h, temperature of 30°C and pH 4.5. During the optimization of reaction conditions, the enzyme showed maximum activity in sodium citrate buffer (50 mM) of pH 5.5 at 50°C reaction temperature for 15 minutes of incubation. The enzyme showed greater affinity for polygalacturonic acid as substrate (0.5%). Km and Vmax values were 0.15 mg/ml and 4.58 μmol/ml/min. The effect of various phenolics, thiols, protein inhibitors and metal ions on the enzyme activity was investigated. The enzyme was quite stable at 4°C and 30°C. At 40°C the half life of the enzyme was 6 h and at 60°C it was 2 h.

Biotechnological potential of pectinolytic complexes of fungi

Plant cell wall-degrading enzymes, such as cellulases, hemicellulases and pectinases, have been extensively studied because of their well documented biotechnological potential, mainly in the food industry. In particular, lytic enzymes from filamentous fungi have been the subject of a vast number of studies due both to their advantages as models for enzyme production and their characteristics. The demand for such enzymes is rapidly increasing, as are the efforts to improve their production and to implement their use in several industrial processes, with the goal of making them more efficient and environment-friendly. The present review focuses mainly on pectinolytic enzymes of filamentous fungi, which are responsible for degradation of pectin, one of the major components of the plant cell wall. Also discussed are the past and current strategies for the production of cell wall-degrading enzymes and their present applications in a number of biotechnological areas.