Kinetics, detergent compatibility and feather-degrading capability of alkaline protease from Bacillus subtilis AKAL7 and Exiguobacterium indicum AKAL11 produced with fermentation of organic municipal solid wastes

Evaluating the industrial potential of naturally occurring proteases: A focus on kinetic and thermodynamic parameters

Thermodynamic and kinetic parameters, such as enthalpy, entropy, and free energy, are crucial in evaluating enzyme stability and activity. These parameters, including the free energy of activation (ΔG#) and the Gibbs free energy of inactivation (ΔG*), are important for predicting energy requirements and reaction rates. However, relying solely on these parameters is insufficient in selecting an enzyme for industrial processes. Numerous studies have explored the measurement of thermodynamic parameters for proteases. Unfortunately, some of the definitions and calculations of key parameters such as ΔG#, ΔG*, and substrate-binding free energy have contained significant errors. In this study, these mistakes have been addressed and corrected. Additionally, a new parameter called δ, defined as the difference between ΔG* and ΔG#, has been introduced for the first time. It is argued that δ provides a more reliable measure for predicting the potential industrial application of enzymes. The highest calculated value for δ was found to be 39.6 kJ·mol-1 at 55 °C. Furthermore, this study also presents a comprehensive collection and determination of all thermodynamic and kinetic parameters for proteases, providing researchers and professionals in the field with a valuable resource to compare and understand the relationships between these parameters and the industrial potential of enzymes.

Study on active capacity and detergent application potential of low-temperature alkaline serine protease produced by new strain Exiguobacterium indicum 1.2.3

Microorganisms have long captivated researchers for their potential to produce enzymes with diverse industrial applications. Efficient production of proteases from new strains is crucial as these enzymes play a vital role in breaking down protein bonds, enabling their use in industrial applications. Therefore, a novel Exiguobacterium indicum 1.2.3 was isolated (Istanbul, Turkiye) and characterized in this study. This strain produced alkaline serine protease, which works in lower temperatures (20-40 °C) with casein as a specific substrate. The protease was utterly stable for 3 h at 30 °C. The enzyme was also highly stable in the pH range of 8-11. The optimum activity was obtained at pH 10. The crude enzyme activity was enhanced by various metal ions and retained 147%, 125%, 124%, and 117% of its activity within 1 mM Ca2+, Mn2+, Cu2+, and Mg2+, respectively. The crude enzyme was inactive with phenylmethylsulfonyl fluoride, indicating a serine residue on the active side. The enzyme exhibited a significant proteolytic effect in the presence of surfactants and oxidizing agents. The addition of Tween 80, Triton X-100, and sodium perborate improved enzymatic activity up to 135%, 109%, and 105%, respectively. According to the washing results, the crude enzyme effectively removed the blood on different types of standard pre-stained textiles at 30 °C. In conclusion, Exiguobacterium indicum 1.2.3 is a promising candidate for protease production, with its diverse applications spanning various industrial sectors, particularly detergents.

Biochemical Characterization and Application of a Detergent Stable, Antimicrobial and Antibiofilm Potential Protease from Bacillus siamensis

Proteases are important enzymes that are engaged in a variety of essential physiological functions and have a significant possible use in industrial applications. In this work, we reported the purification and biochemical characterization of a detergent stable, antimicrobial, and antibiofilm potential protease (SH21) produced by Bacillus siamensis CSB55 isolated from Korean fermented vegetable kimchi. SH21 was purified to obtain homogeneity via ammonium sulfate precipitation (40-80%), Sepharose CL-6B, and Sephadex G-75 column. By analyzing the SDS-PAGE and zymogram, it was determined that the molecular weight was around 25 kDa. The enzyme activity was almost completely inhibited in the presence of PMSF and DFP, which indicated that it was a member of the serine protease family. SH21 showed excellent activity with a broad range of pH and temperature, with its maximum pH of 9.0 and temperature of 55 °C. The enzyme had estimated K_m and V_max values of 0.197 mg/mL and 1.22 × 10³ U/mg, respectively. In addition, it preserved good activity in the presence of different organic solvents, surfactants, and other reagents. This enzyme showed good antimicrobial activity that was evaluated by MIC against several pathogenic bacteria. Furthermore, it exhibited strong antibiofilm activity as determined by MBIC and MBEC assay and degraded the biofilms, which were analyzed by confocal microscopic study. These properties established that SH21 is a potent alkaline protease that can be used in industrial and therapeutic applications.

Kinetic and thermodynamic investigations of surfactants adsorption from water by carbide-derived carbon

The objective of the study is to investigate the potential of carbide-derived carbon (CDC) for the adsorptive removal of nonionic t-octylphenoxy poly ethoxy ethanol (TX-100), anionic sodium dodecylbenzene sulfonate (SDBS) and cationic 1-hexadecylpyridinium bromide (HDPB) surfactants from water. The CDC was characterized using TEM, SEM, FTIR, BET, EDS, XPS methods and zeta potential measurements. The effects of adsorption parameters included initial surfactant concentration, contact time, temperature, and pH of the feed solution were evaluated. The adsorption capacity and mechanism were determined by modeling the isotherm, kinetic and thermodynamic data. The kinetics results demonstrated that the adsorption of the surfactant by CDC obeys the pseudo 2^nd order model. The thermodynamic results have shown that surfactants adsorption by CDC is an endothermic and spontaneous process. The Sips model agreed with the adsorption isotherm data of SDBS with R² of 0.987, while both Freundlich and Redlich-Peterson models comply well with adsorption data for TX-100 and HDPB. The hydrophobic and electrostatic interactions were found the dominant mechanisms of the adsorption of the surfactant by CDC. The adsorption capacities of CDC were found to be 442.4, 462.0 and 578.4 mg/g for SDBS, HDPB and TX-100, respectively.