Cold-Active Lipases and Esterases: A Review on Recombinant Overexpression and Other Essential Issues

Cold environments characterised by diverse temperatures close to or below the water freezing point dominate about 80% of the Earth’s biosphere. One of the survival strategies adopted by microorganisms living in cold environments is their expression of cold-active enzymes that enable them to perform an efficient metabolic flux at low temperatures necessary to thrive and reproduce under those constraints. Cold-active enzymes are ideal biocatalysts that can reduce the need for heating procedures and improve industrial processes’ quality, sustainability, and cost-effectiveness. Despite their wide applications, their industrial usage is still limited, and the major contributing factor is the lack of complete understanding of their structure and cold adaptation mechanisms. The current review looked at the recombinant overexpression, purification, and recent mechanism of cold adaptation, various approaches for purification, and three-dimensional (3D) crystal structure elucidation of cold-active lipases and esterase.     

Minocycline Attenuates Lipopolysaccharide-Induced Locomotor Deficit and Anxiety-like Behavior and Related Expression of the BDNF/CREB Protein in the Rat Medial Prefrontal Cortex (mPFC)

Neuroinflammation following lipopolysaccharide (LPS) administration induces locomotor deficits and anxiety-like behaviour. In this study, minocycline was compared to memantine, an NMDA receptor antagonist, for its effects on LPS-induced locomotor deficits and anxiety-like behaviour in rats. Adult male Sprague Dawley rats were administered either two different doses of minocycline (25 or 50 mg/kg/day, i.p.) or 10 mg/kg/day of memantine (i.p.) for 14 days four days prior to an LPS (5 mg/kg, i.p.) injection. Locomotor activity and anxiety-like behaviour were assessed using the open-field test (OFT). The phosphorylated tau protein level was measured using ELISA, while the expression and density of brain-derived neurotrophic factor (BDNF) and cAMP response element-binding (CREB) protein in the medial prefrontal cortex (mPFC) were measured using immunohistochemistry and Western blot, respectively. Minocycline treatment reduced locomotor deficits and anxiety-like behaviour associated with reduced phosphorylated tau protein levels, but it upregulated BDNF/CREB protein expressions in the mPFC in a comparable manner to memantine, with a higher dose of minocycline having better benefits. Minocycline treatment attenuated LPS-induced locomotor deficits and anxiety-like behaviour in rats and decreased phosphorylated tau protein levels, but it increased the expressions of the BDNF/CREB proteins in the mPFC.     

Removal of leachate pollutants using flocculation method at simultaneous factors of optimum pH and Tacca leontopetaloides biopolymer flocculant (TBPF) dosage via face-centred central composite design

The effect of the interaction factor between pH and dosage is important in leachate wastewater treatment. This study aims to remove leachate pollutants such as turbidity, total suspended solid (TSS), chemical oxygen demand (COD) and colour using simultaneous factors of plant-based Tacca leontopetaloides biopolymer flocculant (TBPF) dosage and leachate pH. The flocculation process was carried out through jar test by applying the perikinetic theory and statical analysis (face-centred central composite design). The results found that the optimum leachate pH and TBPF dosage were pH 3 and 150 mg/L, respectively. The highest removal of leachate pollutants reached up to 69% with a second-order perikinetic model; R² = 0.9545 and k = 9 × 10⁻⁶ L/mg/min were obtained. Simultaneous interaction factors between leachate pH and TBPF dosage on turbidity and TSS removal were found significant and hence can be applied in the actual leachate wastewater treatment industry, particularly at the primary stage using the proposed model.     

Production of N-methyldiethanolamine di-ester via heterogeneous transesterification of palm methyl ester over modified calcium oxide catalyst by metal oxides

The production cycle of the heterogeneous catalyzed-transesterification of methyl ester and alkanolamine for the production of esterquats precursor can be considered as a cleaner and sustainable process. This process is an important alternative route as opposed to the conventional homogeneous catalysis as it can eliminates the formation of wastewater, consumes less toxic chemical and reduce the production cost through catalyst reuse. Calcium oxide (CaO)-based catalysts which include pure CaO and modified CaO by other metal oxides were employed in this study for the production of alkanolamine ester, a precursor of esterquats. The basicity and textural properties of these catalysts were characterized using TPD-CO₂ and N₂ physisorption, respectively. Transesterification activity of CaO-based catalysts successfully showed a high di-ester yield of more than 85% at 160°C, 80 mbar, 4 wt% of catalyst dosage, 6 h reaction time, methyl palmitate to N-methyldiethanolamine mole ratio of 2:1 and agitation speed of 150 rpm. ZnO/CaO catalyst rendered the best durability characteristic as it exhibited constant activities for three subsequent runs with 85% di-ester yield. ZnO/CaO showed high catalytic activity similar to pure CaO catalyst with low leaching of Ca active phase and better reusability than that of pure CaO catalyst, that shows loss of its activity after the first cycle.