Stable release of enhanced organic solvent tolerant amylase from Bacillus amyloliquefaciens AMY02 under sub-merged fermentation

552-559This study has been performed to isolate a potential strain able to release the prolific amylase under non-aqueous conditions to meet the current demand in industries to substitute the amylase produced in aqueous media. A bacterial strain that produces organic solvent-stable amylase in the media containing 15% benzene was isolated from the soil. The recovered strain was identified to be Bacillus amyloliquefaciens AMY02by 16S rRNA sequencing. Under sub-merged fermentation, the optimized amylase release by this strain was found with the condition having starch (carbon source), pH 7.0, the temperature at 30°C for 48 h (incubation time). This optimized condition promoted the amylase production to be 2.04-fold higher than the culture was kept under standard condition with the basic media composition. Further, the stability of the enzyme in the presence of 20% organic solvents was assessed by incubating for 2 weeks. The enzyme was found to be active and stable in the presence of benzene, chloroform, o-xylene, and toluene. The higher organic solvent stability of this amylase production by B. amyloliquefaciens under sub-merged fermentation can be an alternative catalyst in non-aqueous media for industrial applications

Stable release of enhanced organic solvent tolerant amylase from Bacillus amyloliquefaciens AMY02 under sub-merged fermentation

This study has been performed to isolate a potential strain able to release the prolific amylase under non-aqueous conditions to meet the current demand in industries to substitute the amylase produced in aqueous media. A bacterial strain that produces organic solvent-stable amylase in the media containing 15% benzene was isolated from the soil. The recovered strain was identified to be Bacillus amyloliquefaciens AMY02by 16S rRNA sequencing. Under sub-merged fermentation, the optimized amylase release by this strain was found with the condition having starch (carbon source), pH 7.0, the temperature at 30°C for 48 h (incubation time). This optimized condition promoted the amylase production to be 2.04-fold higher than the culture was kept under standard condition with the basic media composition. Further, the stability of the enzyme in the presence of 20% organic solvents was assessed by incubating for 2 weeks. The enzyme was found to be active and stable in the presence of benzene, chloroform, o-xylene, and toluene. The higher organic solvent stability of this amylase production by B. amyloliquefaciens under sub-merged fermentation can be an alternative catalyst in non-aqueous media for industrial applications

Encapsulation of fungal extracellular enzyme cocktail in cellulose nanoparticles: enhancement in enzyme stability

We demonstrated the nano-immobilization of fungal enzymes through their encapsulation in cellulose nanoparticles (CNPs). An extracellular enzyme cocktail (a mixture of amylase, protease, lipase, and cellulose) was produced from Aspergillus niger and Phanerochaete chrysosporium through submerged fermentation. The process of encapsulation was carried out through a microemulsion nanoprecipitation method in the presence of a lipid, a surfactant, and a co-surfactant. The morphology of CNPs was determined by field-emission scanning electron microscopy and transmission electron microscopy; CNPs were less than 100 nm in diameter. Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy demonstrated the successful encapsulation of the fungal enzyme cocktail and revealed C and O as its major components. FTIR peaks of CNPs with encapsulated enzymes occurred at 3421.80, 2828.91, 1649.29, 1450.24, and 1061.61 cm−1 as well as in the range of 1050–1150 cm−1. Encapsulated enzymes showed excellent stability with a peak at −70.91 mV in zeta potential studies. Thermogravimetric analysis proved that the CNP-encapsulated enzymes had an initial weight loss at 250C. The encapsulated fungal enzyme cocktail exhibited higher catalytic performance and stability than the free enzymes. The encapsulated fungal enzyme cocktail derived from A. niger at the concentration of 100 µg/mL, showed the highest amylase activity with a clear zone of 2.5 cm. Overall, the results of this research reveal the enhancement in the activity of fungal extracellular enzyme cocktail through nanoencapsulation

Lignin derived nanoparticle intercalation on nitrogen-doped graphene quantum dots for electrochemical sensing of cardiac biomarker

Lignin-scribed graphene (LSG) conjugated with nitrogen-doped graphene quantum dots (N-GQDs) and lignin derived silver nanoparticles (Ag NPs) was developed through a hydrothermal process for the electrochemical sensing of Troponin I, a cardiac biomarker for Acute Myocardial Infarction (AMI). A nanocomposite with optimal conduction mechanism was developed by varying the N-GQDs doped amount intercalated on the surface of LSG. The nanocomposite was characterised by morphological, physical, and structural examinations. The Ag NPs and N-GQDs were found uniformly distributed on the LSG surface, with selective capture of the biotinylated aptamer probe on the bio-electrode indicative of the specific interaction with Troponin I, resulting in an increment in the charge transfer resistance following hybridisation analysis. The detection limit, as determined through impedance spectroscopy, was 1 fM or 30 fg/mL, with high levels of linearity, selectivity, repeatability, and stability of the sensor. This nanocomposite opens a new avenue for array-based medical diagnostics

A quadruplet 3-D laser scribed graphene/MoS2, functionalised N2-doped graphene quantum dots and lignin-based Ag-nanoparticles for biosensing

Troponin I is a protein released into the human blood circulation and a commonly used biomarker due to its sensitivity and specificity in diagnosing myocardial injury. When heart injury occurs, elevated troponin Troponin I levels are released into the bloodstream. The biomarker is a strong and reliable indicator of myocardial injury in a person, with immediate treatment required. For electrochemical sensing of Troponin I, a quadruplet 3D laserscribed graphene/molybdenum disulphide functionalised N2-doped graphene quantum dots hybrid with ligninbased Ag-nanoparticles (3D LSG/MoS2/N-GQDs/L-Ag NPs) was fabricated using a hydrothermal process as an enhanced quadruplet substrate. Hybrid MoS2 nanoflower (H3 NF) and nanosphere (H3 NS) were formed independently by varying MoS2 precursors and were grown on 3D LSG uniformly without severe stacking and restacking issues, and characterized by morphological, physical, and structural analyses with the N-GQDs and AgNPs evenly distributed on 3D LSG/MoS2 surface by covalent bonding. The selective capture of and specific interaction with Troponin I by the biotinylated aptamer probe on the bio-electrode, resulted in an increment in the charge transfer resistance. The limit of detection, based on impedance spectroscopy, is 100 aM for both H3NF and H3 NS hybrids, with the H3 NF hybrid biosensor having better analytical performance in terms of linearity, selectivity, repeatability, and stability