Why is it important to understand substrates if we are to optimize exogenous enzyme efficacy?

Recombinant Fungal Aspartic Endopeptidases: Insights into Protein Hydrolysis and Combined Effect with Pepsin for Animal Feed Application

Protein hydrolysis under acidic conditions can improve the product quality, nutrient availability, and cost efficiency, particularly when neutral or alkaline enzymes are ineffective. Six fungal aspartic endopeptidases (FAPs) were recombinantly expressed as active enzymes in Komagataella phaffi, with peak activity between 30-50 °C and pH 3.0-4.0. Despite FAP1 yielding a higher degree of hydrolysis for soy protein isolate (SPI) than FAP4, mass spectrometry analysis revealed similar cleavage preferences for the two peptidases. FAP1 and FAP4 experienced competitive product inhibition (Ki: 2.8 mg mL-1, Km: 3.2 mg mL-1 for FAP1 and Ki: 9.67 mg mL-1, Km: 6.58 mg mL-1 for FAP4). These findings suggest that Ki and Km values, when studied in isolation, do not always predict a peptidase's hydrolytic efficacy. Among the FAPs, FAP6 notably increased soluble protein content in animal feed by ∼3-fold. FAP1, when combined with pepsin, had a positive effect on the hydrolysis of SPI. These results underscore the potential of FAPs to hydrolyze proteins─specifically, animal feed proteins─in acidic environments.

Purification and characterization of a fungal aspartic peptidase from Trichoderma reesei and its application for food and animal feed protein hydrolyses

BACKGROUND

Various neutral and alkaline peptidases are commercially available for use in protein hydrolysis under neutral to alkaline conditions. However, the hydrolysis of proteins under acidic conditions by applying fungal aspartic peptidases (FAPs) has not been investigated in depth so far. The aim of this study, thus, was to purify a FAP from the commercial enzyme preparation, ROHALASE® BXL, determine its biochemical characteristics, and investigate its application for the hydrolysis of food and animal feed proteins under acidic conditions.

RESULTS

A Trichoderma reesei derived FAP, with an apparent molecular mass of 45.8 kDa (sodium dodecyl sulfate-polyacrylamide gel electrophoresis; SDS-PAGE) was purified 13.8-fold with a yield of 37% from ROHALASE® BXL. The FAP was identified as an aspartate protease (UniProt ID: G0R8T0) by inhibition and nano-LC-ESI-MS/MS studies. The FAP showed the highest activity at 50°C and pH 4.0. Monovalent cations, organic solvents, and reducing agents were tolerated well by the FAP. The FAP underwent an apparent competitive product inhibition by soy protein hydrolysate and whey protein hydrolysate with apparent K_i -values of 1.75 and 30.2 mg*mL^-1 , respectively. The FAP showed promising results in food (soy protein isolate and whey protein isolate) and animal feed protein hydrolyses. For the latter, an increase in the soluble protein content of 109% was noted after 30 min.

CONCLUSION

Our results demonstrate the applicability of fungal aspartic endopeptidases in the food and animal feed industry. Efficient protein hydrolysis of industrially relevant substrates such as acidic whey or animal feed proteins could be conducted by applying fungal aspartic peptidases. © 2022 Society of Chemical Industry.

Impact of an indigenously produced multi-enzyme complex from Bacillus subtilis KT004404 on growth and blood parameters in broiler chicken

A 42-days experiment was conducted on a day old birds (n = 400) to evaluate the effect of enzyme supplements in feed on the growth, blood parameters, phosphorous content in bones, and nitrogen retention. Different treatments included: control (C) without enzyme supplement, while the other three groups included enzyme mixture T1 and T2 with two commercially available enzyme mix, and T3 with indigenously produced multi-enzyme complex from Bacillus subtilis KT004404. Birds that were fed with indigenously produced multi-enzyme complex showed significant weight gain as compared to other groups. The total feed intake of the birds fed with enzyme supplements was higher than the birds in the control group. The feed conversion ratio was significantly improved (p < 0.05) in treatment groups (T1, T2, T3) as compared to the control. The blood parameters which were analyzed included uric acid, triglycerides, total cholesterol, and serum proteins i.e. globulin and albumin. Birds fed with the enzyme in the group T1, T2 and T3 exhibited higher (p < 0.05) body weight gain. Tibia ash content was significantly higher (p < 0.05) in T1, T2, and T3 as compared to the control. The results of the current study indicate that supplementing poultry feed with the exogenous multi-enzyme produced from Bacillus subtilis KT004404 improved the growth of the birds, feed utilization, and exhibited beneficial effects on the blood parameters, phosphorous and nitrogen retention in broiler chicken.