Biochemical analyses of a novel acidophilic GH5 β-mannanase from Trichoderma asperellum ND-1 and its application in mannooligosaccharides production from galactomannans

Discovery and Characterization of Mannan-Specialized GH5 Endo-1,4-β-mannanases: a Strategy for Açaí (Euterpe oleracea Mart.) Seeds Upgrading

The pulp of açaí palm fruits (Euterpe oleracea Mart.) is a valuable export commodity in Brazil. Its production generates 1.6 million tons/year of açaí seeds, a resource largely wasted. The seeds consist mainly of linear β-mannan, offering potential for prebiotic β-mannan-derived oligomers and mannose production. However, the crystalline structures of β-mannan hinder enzymatic hydrolysis. This study aimed to discover and characterize fungal enzymes targeting açaí seed β-mannan using a palm β-mannanase (EgMan5A) as a guide. Recombinant expression, enzyme optimization, kinetics, substrate specificity, and structural modeling were performed. The two fungal enzymes, JaMan5A and SlMan5A, were found to be specific for unsubstituted mannan, showing no activity toward galacto- and glucomannan. Among them, SlMan5A showed the highest activity on açaí seed β-mannan (∼24 U/mg) and other unsubstituted mannan substrates, likely due to its greater thermal robustness. These results provide valuable insights into β-mannan specificity contributing to the sustainable valorization of açaí seeds.

Leveraging protein language model embeddings and logistic regression for efficient and accurate in-silico acidophilic proteins classification

The increasing demand for eco-friendly technologies in biotechnology necessitates effective and sustainable catalysts. Acidophilic proteins, functioning optimally in highly acidic environments, hold immense promise for various applications, including food production, biofuels, and bioremediation. However, limited knowledge about these proteins hinders their exploration. This study addresses this gap by employing in silico methods utilizing computational tools and machine learning. We propose a novel approach to predict acidophilic proteins using protein language models (PLMs), accelerating discovery without extensive lab work. Our investigation highlights the potential of PLMs in understanding and harnessing acidophilic proteins for scientific and industrial advancements. We introduce the ACE model, which combines a simple Logistic Regression model with embeddings derived from protein sequences processed by the ProtT5 PLM. This model achieves high performance on an independent test set, with accuracy (0.91), F1-score (0.93), and Matthew's correlation coefficient (0.76). To our knowledge, this is the first application of pre-trained PLM embeddings for acidophilic protein classification. The ACE model serves as a powerful tool for exploring protein acidophilicity, paving the way for future advancements in protein design and engineering.

Thermophilic β-mannanases from bacteria: production, resources, structural features and bioengineering strategies

β-mannanases are pivotal enzymes that cleave the mannan backbone to release short chain mannooligosaccharides, which have tremendous biotechnological applications including food/feed, prebiotics and biofuel production. Due to the high temperature conditions in many industrial applications, thermophilic mannanases seem to have great potential to overcome the thermal impediments. Thus, structural analysis of thermostable β-mannanases is extremely important, as it could open up new avenues for genetic engineering, and protein engineering of these enzymes with enhanced properties and catalytic efficiencies. Under this scope, the present review provides a state-of-the-art discussion on the thermophilic β-mannanases from bacterial origin, their production, engineering and structural characterization. It covers broad insights into various molecular biology techniques such as gene mutagenesis, heterologous gene expression, and protein engineering, that are employed to improve the catalytic efficiency and thermostability of bacterial mannanases for potential industrial applications. Further, the bottlenecks associated with mannanase production and process optimization are also discussed. Finally, future research related to bioengineering of mannanases with novel protein expression systems for commercial applications are also elaborated.

Improved production of recombinant β-mannanase (TaMan5) in Pichia pastoris and its synergistic degradation of lignocellulosic biomass

Mannan, a highly abundant and cost-effective natural resource, holds great potential for the generation of high-value compounds such as bioactive polysaccharides and biofuels. In this study, we successfully enhanced the expression of constructed GH5 β-mannanase (TaMan5) from Trichoderma asperellum ND-1 by employing propeptide in Pichia pastoris. By replacing the α-factor with propeptide (MGNRALNSMKFFKSQALALLAATSAVA), TaMan5 activity was significantly increased from 67.5 to 91.7 U/mL. It retained higher activity in the presence of 20% ethanol and 15% NaCl. When incubated with a high concentration of mannotriose or mannotetraose, the transglycosylation action of TaMan5 can be detected, yielding the corresponding production of mannotetraose or mannooligosaccharides. Moreover, the unique mechanism whereby TaMan5 catalyzes the degradation of mannan into mannobiose involves the transglycosylation of mannose to mannotriose or mannotetraose as a substrate to produce a mannotetraose or mannopentose intermediate, respectively. Additionally, the production of soluble sugars from lignocellulose is a crucial step in bioethanol development, and it is noteworthy that TaMan5 could synergistically yield fermentable sugars from corn stover and bagasse. These findings offered valuable insights and strategies for enhancing β-mannanase expression and efficient conversion of lignocellulosic biomass, providing cost-effective and sustainable approaches for high-value biomolecule and biofuel production.