Acinetobacter - A Hard to Treat Resilient ICU Pathogen

Objective: To isolate Acinetobacter sp and identify MDR (multidrug resistant) and XDR (extensively drug resistant) isolates from intensive care unit in a tertiary care hospital, Lahore. Methodology: This cross-sectional research was performed retrospectively in a tertiary care hospital, Lahore from January 2022-December 2022. It consisted of 435 specimens from ICU patients processed for culture and sensitivity in microbiology section of Pathology Laboratory, SMCH. The specimens included blood, pus, urine, cerebrospinal fluid, and other body cavity fluids, sputum, bronchial aspirates, wound swabs, ETT, etc. The specimens were cultured on Blood agar (Oxoid UK) and Mac Conkey agar (Oxoid UK) but CLED agar (Oxoid UK) was used for urine.  After overnight incubation at 37°C, Acinetobacter sp were identified by morphology and biochemical reactions using Analytical profile index (API) 20 NE (Biomerieux, France). Results: One hundred and seventy-five cases revealed Gram negative bacteria (GNB) and 31 (17.71%) of the GNB were Acinetobacter sp. Fifteen isolates of Acinetobacter sp were obtained from respiratory secretions,7 from pus, 6 from urine, 2 from ETT, and 1 isolate from blood sample. A total of 31 isolates were obtained. Thirteen (41.9%) Acinetobacter isolates were MDR and 9 (29.0%) turned out to be XDR. The remaining 9 isolates exhibited satisfactory susceptibility. Conclusion: Acinetobacter sp. is responsible for a significant bulk of drug resistant ICU associated infections and is increasingly developing resistance as evident by 41.9% MDR and 29.0% XDR isolates

Lewatit-immobilized lipase from Bacillus pumilus as a new catalyst for biodiesel production from tallow: response surface optimization, fuel properties and exhaust emissions

Biodiesel is currently regarded as a sustainable and renewable alternative to depleting fossil fuels such as petro-diesel. Biodiesel production on a large scale could have a positive impact on the energy sector and the environment by lowering greenhouse gas emissions. Disadvantages of biodiesel include utilization of high-cost edible oils for production of biofuels, generation of wastewater and inability to recycle catalysts after alkaline-catalyzed methanolysis. The objectives of the current study were to utilize low-cost, inedible tallow to produce biodiesel from Lewatit-immobilized lipase produced from Bacillus pumilus and to measure the fuel properties and exhaust emissions of the resulting fatty acid methyl esters. Response surface methodology was used to optimize reaction conditions and alkaline (potassium hydroxide; KOH) catalysis was performed for comparison. A conversion of 96% was achieved by two step chemical-mediated transesterification, whereas conversion was 67% for the single step lipase-mediated method. Acid pre-treatment was needed in the case of KOH-catalyzed transesterification to reduce the acid value of tallow from 17.6 to 1.3 mg KOH/g, whereas the Lewatit-immobilized lipase was able to efficiently catalyse both transesterification of glycerides and esterification of free fatty acids. To the best of our knowledge, the lipase from B. pumilus has not yet been studied for biodiesel production from tallow. Fuel properties of the resulting optimized biodiesel were within the limits prescribed in ASTM D6751 and EN 14214. In addition, exhaust emissions studies revealed reduced CO and PM relative to petro-diesel. In both cases, reductions were greater as the percentage of biodiesel increased in blends with petro-diesel. However, NOx emissions were elevated versus petrodiesel in blends that contained 50% or more of biodiesel. This research reveals new ways for utilization of waste animal fats for biodiesel production as well as a new efficient lipase source that yields more products and provides environmental and economic security

Fe3O4-PDA-lipase as surface functionalized nano biocatalyst for the production of biodiesel using waste cooking oil as feedstock: characterization and process optimization

Synthesis of surface modified/multi-functional nanoparticles has become a vital research area of material science. In the present work, iron oxide (Fe3O4) nanoparticles prepared by solvo-thermal method were functionalized by polydopamine. The catechol groups of polydopamine at the surface of nanoparticles provided the sites for the attachment of Aspergillus terreus AH-F2 lipase through adsorption, Schiff base and Michael addition mechanisms. The strategy was revealed to be facile and efficacious, as lipase immobilized on magnetic nanoparticles grant the edge of ease in recovery with utilizing external magnet and reusability of lipase. Maximum activity of free lipase was estimated to be 18.32 U/mg/min while activity of Fe3O4-PDA-Lipase was 17.82 U/mg/min (showing 97.27% residual activity). The lipase immobilized on polydopamine coated iron oxide (Fe3O4_PDA_Lipase) revealed better adoptability towards higher levels of temperature/pH comparative to free lipase. The synthesized (Fe3O4_PDA_Lipase) catalyst was employed for the preparation of biodiesel from waste cooking oil by enzymatic transesterification. Five factors response surface methodology was adopted for optimizing reaction conditions. The highest yield of biodiesel (92%) was achieved at 10% Fe3O4_PDA_Lipase percentage concentration, 6:1 CH3OH to oil ratio, 37 °C temperature, 0.6% water content and 30 h of reaction time. The Fe3O4-PDA-Lipase activity was not very affected after first four cycles and retained 25.79% of its initial activity after seven cycles. The nanoparticles were characterized by FTIR (Fourier transfer infrared) Spectroscopy, XRD (X-ray diffraction) and TEM (transmission electron microscopy), grafting of polydopamine on nanoparticles was confirmed by FTIR and formation of biodiesel was evaluated by FTIR and GC-MS (gas chromatography-mass spectrometry) analysis