Switchable deep eutectic solvent driven micellar extractive fermentation of ultrapure fibrin digesting enzyme from Bacillus subtilis

Switchable hydrophilicity solvent-assisted solidified floating organic drop microextraction for separation and determination of arsenic in water and fish samples

The aim of the current study was to separate and determine arsenic in water and fish samples using a novel and green solidified floating organic drop microextraction (SFODME), which is based on switchable hydrophilicity solvent (SHS)-assisted procedure followed by hydride generation atomic absorption spectrometry (HG-AAS). The 4-((2-hydroxyquinoline-7-yl)diazenyl)-N-(4-methylisoxazol-3-yl)benzene sulfonamide (HDNMBA) and tertiary amine (4-(2-aminoethyl)-N,N-dimethylbenzylamine (AADMBA) were used as ligand and SHS, respectively. The use of SHS promotes quantitative extraction of arsenic complexes into an extraction solvent (1-undecanol). Some factors that impact extraction recovery were studied. Under optimal conditions, the limit of detection (LOD) and limit of quantification (LOQ) were 0.005 μg L-1 and 0.015 μg L-1, respectively. The calibration graph was linear up to 900.0 μg L-1 arsenic, with the enrichment factor is 267. The proposed SHS-SFODME methodology for arsenic quantification in water and fish samples was successfully implemented. The environmental friendliness and safety of proposed method were approved by the Analytical Greenness Calculator (AGREE) and the Blue Applicability Grade Index (BAGI) tools.

Sustainable production and preparative purification of thermostable alkaline α-amylase by Bacillus simplex (ON754233) employing natural deep eutectic solvent-based extractive fermentation

Using PEG-based deep eutectic solvents (PDES), the current study proposes extractive fermentation as a sustainable process integration for the production and purification of α-amylase from Bacillus simplex (ON754233). Glucose: PEG 400 outperformed five PDES in terms of tie lie length (58) and slope value (1.23) against sodium sulphatt. Apple cider pomace was used as a low-cost, sustainable carbon source to produce-amylase, with a maximum enzyme production of 2200.13 U/mL. PDES concentration (20% w/v), salt (12.75 w/v), and apple waste (2.75 g/mL) were all optimized using response surface methodology. When scaled upto 3 L benchtop bioreactor, extractive fermentation was proved to be better technology with maximum recovery of 92.4% with highest partition coefficient (3.59). The partially purified enzyme was further purified using a Sephadex G 100 followed by DEAE-Sephadex anion exchange chromatography with a purity fold of 33. The enzyme was found to be thermostable at the temperature (60 °C), remains alkaline (pH 8), and the activity was stimulated in the presence of Mg2+ ions. With SDS PAGE electrophoresis, the molecular weight was found to be around 140 kDa. Finally, the enzyme kinetics parameters were evaluated with observed Km (0.00396 mM) and Vmax (37.87 U/mL). Thus scaling up extractive fermentation entails increasing production capacity with improved extraction efficiency using green solvents.

Simultaneous production and sustainable eutectic mixture based purification of narringinase with Bacillus amyloliquefaciens by valorization of tofu wastewater

The current investigation is being executed for sustainable one-pot production and purification of naringinase using natural deep eutectic solvent-based extractive fermentation. Five natural deep eutectic solvents were prepared and their physicochemical properties were determined as a function of temperature. Tofu wastewater was used as a low-cost substrate for naringinase production and simultaneous in-situ purification of the enzyme was accomplished by employing NADES. Optimal conditions of influential factors like concentrations of NADES (74.5% w/w), Na₂SO₄ (15% w/v) and tofu wastewater (1.5% w/w) resulted in an effective yield of naringinase (249.6 U/ml). Scale-up of naringinase production with a 3 l custom made desktop bioreactor was accomplished and effective regeneration of NADES was established. NADES exhibits selectivity during extraction even after the fifth cycle proving it to be tailor-made. The resulting active enzyme was quantified by size exclusion chromatography (736.85 U/mg). Ultrapure enzyme fraction was obtained with anion exchange chromatography yielding maximum purity of (63.2 U/ml) and specific naringinase activity of (3516 U/mg). The in-vitro debittering activity of the resulting ultrapure enzyme fraction was determined with grape juice resulting in naringin and limonin removal of [23.4% (w/w)] and [64.3% (w/w)] respectively.