Chemoenzymatic lignin valorization: Production of epoxidized pre-polymers using Candida antarctica lipase B

Magnetic whole-cell biocatalyst based on intracellular lipases of Candida catenulata as promising technology for green synthesis of epoxy fatty acids

This study focuses on the development a green synthesis of epoxy fatty acids (EFAs) which are commonly used as the plasticizer in polymer industries. The intracellular lipases of Candida catenulata cells as a whole-cell biocatalyst (WCB) were examined in the bio-epoxidation of free fatty acids (FFAs) with hydrogen peroxide. The FFAs in soybean soap stock, an industrial by-product of vegetable oil factories, was used as the feedstock of the process. To remove phosphates from soap stock a degumming process was tested before the bio-epoxidation reaction and results revealed that the EFAs yield was improved using the degummed fatty acids (DFAs). The attachments of magnetic Fe3O4 nanoparticles to the surface of WCBs facilitated the recovery of the biocatalyst, and were improved stabilities. The activation energy for the magnetic whole-cell biocatalysts (MWCB) was 48.54 kJ mol-1, which was lower than the WCB system (51.28 kJ mol-1). The EFA yield was about 47.1 % and 33.8 % after 3 h for the MWCBs and 2 h for the WCBs, respectively. The MWCBs displayed acceptable reusability in the repetitious bio-epoxidation reaction with maintaining 59 % of the original activity after 5 cycles whereas the performance of the WCBs was 5.9 % at the same conditions. The effects of influential factors such as reaction time, molar ratio of H2O2 to CC, and batch and semi-batch operations were investigated for both biocatalyst systems. The quality of EFAs was characterized by FTIR and GC-MS analyses.

The Biomodified Lignin Platform: A Review

A reliance on fossil fuel has led to the increased emission of greenhouse gases (GHGs). The excessive consumption of raw materials today makes the search for sustainable resources more pressing than ever. Technical lignins are mainly used in low-value applications such as heat and electricity generation. Green enzyme-based modifications of technical lignin have generated a number of functional lignin-based polymers, fillers, coatings, and many other applications and materials. These bio-modified technical lignins often display similar properties in terms of their durability and elasticity as fossil-based materials while also being biodegradable. Therefore, it is possible to replace a wide range of environmentally damaging materials with lignin-based ones. By researching publications from the last 20 years focusing on the latest findings utilizing databases, a comprehensive collection on this topic was crafted. This review summarizes the recent progress made in enzymatically modifying technical lignins utilizing laccases, peroxidases, and lipases. The underlying enzymatic reaction mechanisms and processes are being elucidated and the application possibilities discussed. In addition, the environmental assessment of novel technical lignin-based products as well as the developments, opportunities, and challenges are highlighted.

Machine learning aided experimental approach for evaluating the growth kinetics of Candida antarctica for lipase production

A hybrid machine learning (ML) aided experimental approach was proposed in this study to evaluate the growth kinetics of Candida antarctica for lipase production. Different ML models were trained and optimized to predict the growth curves at various substrate concentrations. Results on comparison demonstrate the superior performance of the Gradient boosting regression (GBR) model in growth curves prediction. GBR-based growth kinetics was found to be matching well with the results of the conventional experimental approach while significantly reducing the experimental effort, time, and resources by ∼ 50%. Further, the activity and enzyme kinetics of lipase produced in this study was investigated on hydrolysis of p-nitrophenyl butyrate resulting in a maximum lipase activity of 24.07 U at 44 h. The robustness and significance of developed kinetic models were ensured through detailed statistical analysis. The application of the proposed hybrid approach can be extended to any other microbial process.

A Review on the Lignin Biopolymer and Its Integration in the Elaboration of Sustainable Materials

Lignin is one of the wood and plant cell wall components that is available in large quantities in nature. Its polyphenolic chemical structure has been of interest for valorization and industrial application studies. Lignin can be obtained from wood by various delignification chemical processes, which give it a structure and specific properties that will depend on the plant species. Due to the versatility and chemical diversity of lignin, the chemical industry has focused on its use as a viable alternative of renewable raw material for the synthesis of new and sustainable biomaterials. However, its structure is complex and difficult to characterize, presenting some obstacles to be integrated into mixtures for the development of polymers, fibers, and other materials. The objective of this review is to present a background of the structure, biosynthesis, and the main mechanisms of lignin recovery from chemical processes (sulfite and kraft) and sulfur-free processes (organosolv) and describe the different forms of integration of this biopolymer in the synthesis of sustainable materials. Among these applications are phenolic adhesive resins, formaldehyde-free resins, epoxy resins, polyurethane foams, carbon fibers, hydrogels, and 3D printed composites.

Harnessing the Power of Enzymes for Tailoring and Valorizing Lignin

Lignin, a structural component of lignocellulosic plants, is an alternative raw material with enormous potential to replace diminishing fossil-based resources for the sustainable production of many chemicals and materials. Unfortunately, lignin's heterogeneity, low reactivity, and strong intra- and intermolecular hydrogen interactions and modifications introduced during the pulping process present significant technical challenges. However, the increasing ability to tailor lignin biosynthesis pathways by targeting enzymes and the continued discovery of more robust biocatalysts are enabling the synthesis of novel valuable products. This review summarizes how enzymes involved in lignin biosynthesis pathways and microbial enzymes are being harnessed to produce chemicals and materials and to upgrade lignin properties for the synthesis of a variety of value-added lignin industrial products.

Novozym 435: the “perfect” lipase immobilized biocatalyst?

Novozym 435 (N435) is a commercially available immobilized lipase produced by Novozymes with its advantages and drawbacks.