Munazza Gull

Pyrolysis, kinetics analysis, thermodynamics parameters and reaction mechanism of Typha latifolia to evaluate its bioenergy potential

This work was focused on understanding the pyrolysis of Typha latifolia. Kinetics, thermodynamics parameters and pyrolysis reaction mechanism were studied using thermogravimetric data. Based on activation energies and conversion points, two regions of pyrolysis were established. Region-I occurred between the conversion rate 0.1-0.4 with peak temperatures 538K, 555K, 556K at the heating rates of 10Kmin-1, 30Kmin-1, and 50Kmin-1, respectively. Similarly, the Region-II occurred between 0.4 and 0.8 with peak temperatures of 606K, 621K, 623K at same heating rates. The best model was diffusion mechanism in Region-I. In Region-II, the reaction order was shown to be 2nd and 3rd. The values of activation energy calculated using FWO and KAS methods (134-204kJmol-1) remained same in both regions reflecting that the best reaction mechanism was predicted. Kinetics and thermodynamic parameters including E, ΔH, ΔS, ΔG shown that T. latifolia biomass is a remarkable feedstock for bioenergy.

Bioenergy potential of Wolffia arrhiza appraised through pyrolysis, kinetics, thermodynamics parameters and TG-FTIR-MS study of the evolved gases

This study evaluated the bioenergy potential of Wolffia arrhiza via pyrolysis. The biomass was collected from the pond receiving city wastewater. Oven dried powdered biomass was exposed to thermal degradation at three heating rates (10, 30 and 50° C min-1) using Thermogravimetry-Differential Scanning Calorimetry analyzer in an inert environment. Data obtained were subjected to the isoconversional models of Kissenger-Akahira-Sunose (KSA) and Flynn-Wall-Ozawa (FWO) to elucidate the reaction chemistry. Kinetic parameters including, Ea (136-172 kJmol-1) and Gibbs free energy (171 kJmol-1) showed the remarkable bioenergy potential of the biomass. The average enthalpies indicated that the product formation is favored during pyrolysis. Advanced coupled TG-FTIR-MS analyses showed the evolved gases to contain the compounds containing CO functional groups (aldehydes, ketones), aromatic and aliphatic hydrocarbons as major pyrolytic products. This low-cost abundant biomass may be used to produce energy and chemicals in a cost-efficient and environmentally friendly way.

Domain wise docking analyses of the modular chitin binding protein CBP50 from Bacillus thuringiensis serovar konkukian S4

This paper presents an in silico characterization of the chitin binding protein CBP50 from B. thuringiensis serovar konkukian S4 through homology modeling and molecular docking. The CBP50 has shown a modular structure containing an N-terminal CBM33 domain, two consecutive fibronectin-III (Fn-III) like domains and a C-terminal CBM5 domain. The protein presented a unique modular structure which could not be modeled using ordinary procedures. So, domain wise modeling using MODELLER and docking analyses using Autodock Vina were performed. The best conformation for each domain was selected using standard procedure. It was revealed that four amino acid residues Glu-71, Ser-74, Glu-76 and Gln-90 from N-terminal domain are involved in protein-substrate interaction. Similarly, amino acid residues Trp-20, Asn-21, Ser-23 and Val-30 of Fn-III like domains and Glu-15, Ala-17, Ser-18 and Leu-35 of C-terminal domain were involved in substrate binding. Site-directed mutagenesis of these proposed amino acid residues in future will elucidate the key amino acids involved in chitin binding activity of CBP50 protein.

Bioenergy potential of Eichhornia crassipes assessed via thermodynamics and kinetics analyses

BACKGROUND Eichhornia crassipes is an aquatic plant well known for its role in soil reclamation due to the containment of valuable nutrients. Moreover, its biomass is an abundant and low-cost biological resource. Pyrolysis of a biomass offers one of the cleanest methods to harness the bioenergy stored in the biomass. OBJECTIVE The present study was focused on evaluating the bioenergy potential of Eichhornia crassipes via pyrolysis. METHODS Biomass of E. crassipes was collected from a municipal wastewater pond. Oven dried powdered biomass of E. crassipes was subjected to pyrolysis at three heating rates including 10, 30 and 50 °C min-1 in a simultaneous Thermogravimetry-Differential Scanning Calorimetry analyzer under an inert environment containing nitrogen. Data obtained were subjected to isoconversional models of Kissenger-Akahira-Sunose (KSA) and Flynn-Wall-Ozawa (FWO) to understand the reaction chemistry. RESULTS Kinetic parameters have shown that the pyrolysis followed first-order reaction kinetics. The average values of activation energies (129.71-133.03 kJ mol-1) and thermodynamic parameters including high heating values (18.12 MJ kg-1), Gibbs free energies (171-180 kJ mol-1) and enthalpy of reaction (124-127 kJ mol-1) have shown the remarkable bioenergy potential of this biomass. CONCLUSION This low-cost biomass may be used to produce liquids, gases, and biochar in a costefficient and environmentally friendly way via pyrolysis or co-pyrolysis in the future.

Synthesis, Electrochemical and Antimicrobial Activity of Colloidal Copper Nanoparticles

The colloidal dispersion of copper nanoparticles (CuNPs), prepared by reducing Cu2+ ions using ascorbic acid, was characterized and used for electrochemical and antimicrobial activity investigations. By depositing CuNPs onto the glassy carbon electrode (GCE) surface the CuNPs/GCE was constructed, which was used to study electrochemical behavior of CuNPs and to carry out direct electrochemical detection of trichloroacetic acid (TCA) and 2-chlorophenol (2-CP) in neutral medium. Excellent electrocatalytic ability of CuNPs, assessed by cyclic voltammetry (CV), for the reduction of TCA and 2-CP was detected. The electrochemical impedance analysis (EIS) of the GCE and CuNPs modified GCE evidenced higher charge transfer activity across the modified electrode surface. The antibacterial activity tests of as-synthesized CuNPs on the selected pathogenic strains of Salmonella group B (7.9±0.912), Klebsiella pneumonia (8.33±1.561), Escherichia Coli (15.65±1.612), Enterococcus faecalis (5.4±0.612), Staphylococcus aureus (12.6±1.531) and yeast Candida albicans (11.4.3±1.512), respectively, were performed. The results indicated that the use of CuNPs can be pursued as an alternative strategy (to antibiotics) for averting infections by controlling bacterial adhesion and bacterial bio-film formation against microbial infections.

Heterologous Expression of the Antifungal β-chitin Binding Protein CBP24 from Bacillus thuringiensis and its Synergistic Action with Bacterial Chitinases

The genome sequence analysis of Bacillus thuringiensis serovar konkukian S4 has shown to contain two chitinases (Chi74, Chi39) and two chitin-binding proteins (CBP50 and CBP24). The Chi74, Chi39 and CBP50 have been characterized previously. The chitin-binding protein CBP24 was cloned and heterologously expressed in Escherichia coli. The recombinant protein was purified using a Ni-NTA purification system. The purified protein was used to study its substrate binding activity using crystalline chitin variants as substrates. The Bmax and Kd values have shown that it preferably binds to β-type of the crystalline chitin at a range of pH with peak activity between 5.5-7.5. To elucidate the role of CBP24 in the chitin degradation system of S4, the purified chitinases Chi74, Chi39 along with the ChiA from Serratia proteamcualans were used in different combinations with the CBP24 and chitinolytic activity was assayed. It was shown that the CBP24 acts synergistically with chitin degradation activity of bacterial chitinases non-specifically. Moreover, the CBP24 has shown antifungal activity against plant pathogenic fungi Fusarium oxysporum and Rhizoctonia solani. The present study will lead us to develop a technology for environmental friendly conversion of chitin to valuable products.

Heterologous synthesis and recovery of advanced biofuels from bacterial cell factories

BACKGROUND Microbial engineering to produce advanced biofuels is currently the most encouraging approach in renewable energy. Heterologous synthesis of biofuels and other useful industrial chemicals using bacterial cell factories has radically diverted the attentions from the native synthesis of these compounds. However, recovery of biofuels from the media and cellular toxicity are the main hindrances to successful commercialization of advanced biofuels. Therefore, membrane transporter engineering is gaining increasing attentions from all over the world. OBJECTIVE The main objective of this review is to explore the ways to increase the microbial production of biofuels by counteracting the cellular toxicity and facilitating their easier recovery from media. CONCLUSION Microbial synthesis of industrially viable compounds such as biofuels has been increased due to genomic revolution. Moreover, advancements in protein engineering, gene regulation, pathway portability, metabolic engineering and synthetic biology led the focus towards the development of robust and cost-effective systems for biofuel production. The most convenient way to combat cellular toxicity and to secrete biofuels is the use of membrane transport system. The use of membrane transporters is currently a serious oversight as do not involve chemical changes and contribute greatly to efflux biofuels in extracellular milieu. However, overexpression of transport systems can also be detrimental to cell, so, in future, structure-based engineering of transporters can be employed to evaluate optimum expression range, to increase biofuel specificity and transport rate through structural studies of biofuel molecules.

Diversity, Physiochemical and Phylogenetic Analyses of Bacteria Isolated from Various Drinking Water Sources

Objective: To evaluate the indigenous bacterial strains of drinking water from the most commercial water types including bottled and filtered water that are currently used in Saudi Arabia. Methods: Thirty randomly selected commercial brands of bottled water were purchased from Saudi local markets. Moreover, samples from tap water and filtered water were collected in sterilized glass bottles and stored at 4°C. Biochemical analyses including pH, temperature, lactose fermentation test (LAC), indole test (IND), methyl red test (MR), Voges-Proskauer test (VP), urease test (URE), catalase test (CAT), aerobic and anaerobic test (Ae/An) were measured. Molecular identification and comparative sequence analyses were done by full length 16S rRNA gene sequences using gene bank databases and phylogenetic trees were constructed to see the closely related similarity index between bacterial strains. Results: Among 30 water samples tested, 18 were found positive for bacterial growth. Molecular identification of four selected bacterial strains indicated the alarming presence of pathogenic bacteria Bacillus spp. in most common commercial types of drinking water used in Saudi Arabia. Conclusion: The lack of awareness about good sanitation, poor personal hygienic practices and failure of safe water management and supply are the important factors for poor drinking water quality in these sources, need to be addressed.

Antimicrobial Activity and Biochemical Profiling of Selected Medicinal Plants Against Blood Cancer Clinical Isolates

1Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia. 2Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia. 3Department of Botany, Faculty of Science, Govt: College University (Women) Faisalabad, Pakistan. 4Department of Bioinformatics & Biotechnology, Government College University Faisalabad, 38000, Pakistan.