Asif Jamal

Combined efficacy of biologically synthesized silver nanoparticles and different antibiotics against multidrug-resistant bacteria.

Biological synthesis of nanoparticles is a growing innovative approach that is relatively cheaper and more environmentally friendly than current physicochemical processes. Among various microorganisms, fungi have been found to be comparatively more efficient in the synthesis of nanomaterials. In this research work, extracellular mycosynthesis of silver nanoparticles (AgNPs) was probed by reacting the precursor salt of silver nitrate (AgNO3) with culture filtrate of Aspergillus flavus. Initially, the mycosynthesis was regularly monitored by ultraviolet-visible spectroscopy, which showed AgNP peaks of around 400–470 nm. X-ray diffraction spectra revealed peaks of different intensities with respect to angle of diffractions (2θ) corresponding to varying configurations of AgNPs. Transmission electron micrographs further confirmed the formation of AgNPs in size ranging from 5–30 nm. Combined and individual antibacterial activities of the five conventional antibiotics and AgNPs were investigated against eight different multidrug-resistant bacterial species using the Kirby–Bauer disk-diffusion method. The decreasing order of antibacterial activity (zone of inhibition in mm) of antibiotics, AgNPs, and their conjugates against bacterial group (average) was; ciprofloxacin + AgNPs (23) . imipenem + AgNPs (21) > gentamycin + AgNPs (19) > vancomycin + AgNPs (16) > AgNPs (15) . imipenem (14) > trimethoprim + AgNPs (14) > ciprofloxacin (13) > gentamycin (11) > vancomycin (4) > trimethoprim (0). Overall, the synergistic effect of antibiotics and nanoparticles resulted in a 0.2–7.0 (average, 2.8) fold-area increase in antibacterial activity, which clearly revealed that nanoparticles can be effectively used in combination with antibiotics in order to improve their efficacy against various pathogenic microbes.

Bacterial succession and degradative changes by biofilm on plastic medium for wastewater treatment

Biofilms contain a diverse range of microorganisms and their varying extracellular polysaccharides. The present study has revealed biofilm succession associated with degradative effects on plastic (polypropylene) and contaminants in sludge. The wet weight of biofilm significantly (p < 0.05) increased; from 0.23 ± 0.01 to 0.44 ± 0.01 g. Similarly, the dry weight of the biofilm increased from 0.02 to 0.05 g. Significant reduction in pathogens (E. coli and feacal coliforms) by MPN technique (>80%) and in chemical parameters (decrease in COD, BOD5 of 73.32 and 69.94%) representing diminution of organic pollutants. Energy dispersive X‐ray spectroscopy (EDS) of plastic revealed carbon and oxygen contents, further surface analysis of plastic by scanning electron microscopy (SEM) revealed emergence of profound bacterial growth on the surface. Fourier transform infrared (FTIR) spectroscopy conforms its biotransformation under aerobic conditions after 8 weeks. New peaks developed at the region 1050 and 969 cm−1 indicating CO and CC bond formation. Thus plastic with 6 weeks old aerobic biofilm (free of pathogens, max. weight, and OD, efficient COD & BOD removal ability) is suggested to be maintained in fixed biofilm reactors for wastewater treatment.

Isolation and Antibiogram of Clostridium tetani from Clinically Diagnosed Tetanus Patients

Clostridium tetani, the etiologic agent of tetanus, produces a toxin that causes spastic paralysis in humans and other vertebrates. This study was aimed for isolation, identification, and determination of antimicrobial susceptibility of C. tetani from clinically diagnosed tetanus patients. Isolation was done from deep-punctured tissues of the foot and arm injuries of 80 clinically diagnosed tetanus patients from the Pakistan Institute of Medical Sciences hospital. We successfully screened out five C. tetani isolates out of 80 samples based on the strain-specific characteristics confirmed through biochemical testing and toxin production. A disc diffusion method was used for antimicrobial susceptibilities and C. tetani isolates showed susceptibility to cefoperazone, chloramphenicol, metronidazole, penicillin G, and tetracycline, but were found to be resistant to erythromycin and ofloxacin. During animal testing, all the infected mice developed symptoms of tetanus. The results showed that identification of C. tetani is possible using biochemical and molecular tools and that the strains of C. tetani isolated had not developed resistance against the antibiotics most often used for the treatment of tetanus.

Polymeric pollutant biodegradation through microbial oxidoreductase: A better strategy to safe environment

The detoxification of xenobiotic organic compounds by various microorganisms through oxidative coupling is facilitated with oxidoreductases. With the help of energy yielding biochemical reactions, these microbes extract energy for their metabolic pathway. They promote the transfer of electrons from a reduced organic substrate to another chemical compound. During such oxidation-reduction reactions, the toxic polymeric substance is finally oxidized into harmless compounds. Enzymatic bioremediation of toxic organic pollutant is a very effective strategy in complex environmental conditions. Oxidoreductases enzymes have a significant potential for the bioremediation of the xenobiotic compounds. Various electron donor complex polymeric substrates containing Phenol and aromatic amines are oxidized by peroxidase in the presence of H2O2 while O2 in the case of dioxygenase. This review attempts to present relevant information on the peroxidases and dioxygenase from various microbial isolates involved in the biodegradation of a wide range of pollutants.

Isolation and Characterization of Coal Solubilizing Aerobic Microorganisms from Salt Range Coal Mines, Pakistan

ABSTRACT Microbial solubilization of coal has been considered as a promising technology to convert raw coal into valuable products. In the present study, initially a total of 50 different aerobic bacterial and fungal isolates have been isolated from soil, coal and water samples of Dulmial Coal Mines, Chakwal, Pakistan, but on the basis of solubilization potential, only four isolates were selected for further study. The intensity of biosolubilization was measured by determining the weight loss of the coal pieces, which was observed to be about 25.93% by Pseudomonas sp. AY2, 36.36% by Bacillus sp. AY3 and 50% by Trichoderma sp. AY6, while Phanerochaete sp. AY5 showed maximum coal solubilization potential i.e. 66.67% in 30 days. UV/Vis spectrum revealed an increase in the pattern of absorbance of all treated samples compared to control referring to solubilization. Fourier transform infrared spectroscopy indicated alterations in the structure of treated coal in comparison to control coal suggesting breakdown in the complex structure of coal. The major absorbance bands in infrared spectroscopy for solubilization product were attributed to carbonyl (1,600 cm−1), hydroxyl (3,450 cm−1), cyclane (2,925 cm−1), ether linkage (1,000–1,300 cm−1), carboxyl (3,300–2,500 cm−1) and side chains of aromatic ring (1,000–500 cm−1). The presence of microorganisms and surface erosion of coal residues compared to control samples were observed by scanning electron microscopy, which suggested that isolated microorganisms were able to survive in coal for a longer period of time. Therefore, the present study concluded that microorganisms isolated from coal mines have excellent potential for coal solubilization which is considered as a crucial step in coal methanogenesis allowing them to be used successfully for in situ methane production to meet future energy demands.

Isolation and screening of protease producing thermophilic Bacillus strains from different soil types of Pakistan

Thermophilic bacteria produce commercially useful proteases, active at high temperature. Due to growing demand of proteases application in different industries, the present study was designed to isolate protease producing Bacillus strains. Nine strains were isolated from three different ecological sources and qualitatively screened on skim milk agar. The Bacillus strain PB1 showed 5.4 cm zone of hydrolysis. The screened protease producing strain was further identified on the basis of morphological, biochemical (API 20 and API 50 CHB) and 16 s rRNA molecular identification as Bacillus licheniformis PB1 (Accession EU650317).

Lignin peroxidase isoenzyme: a novel approach to biodegrade the toxic synthetic polymer waste

ABSTRACT Fungal metabolites are playing an immense role in developing various sustainable waste treatment processes. The present study aimed at production and characterization of fungal lignin peroxidase (EC 1.11.1.14) with a potential to degrade Polyvinyl Chloride. Optimization studies revealed that the maximum enzyme production occurred at a temperature 25°C, pH 5 in the 4th week of the incubation period with fungal strain. Enzyme assay was performed to find out the dominating enzyme in the culture broth. The molecular weight of the enzyme was found to be 46 kDa. Partially purified lignin peroxidase from Phanerocheate chrysosporium was used for the degradation of PVC films. A significant reduction in the weight of PVC film was observed (31%) in shake flask experiment. FTIR spectra of the enzyme-treated plastic film revealed structural changes in the chemical composition, indicating a specific peak at 2943 cm−1 that corresponded to alkenyl C–H stretch. Moreover, deterioration on the surface of PVC films was confirmed by Scanning Electron Microscopy tracked through activity assay for the lignin peroxidase. Extracellular lignin peroxidases from P. chrysosporium play a significant role in the degradation of complex polymeric compounds like PVC.

MATHEMATICAL MODELING OF BIOPROCESS VARIABLES FOR IMPROVED PRODUCTION OF RHAMNOLIPID FROM Pesudomonas aeruginosa STRAIN JQ

Surfactants are one of the most important products of the chemical industry for being extensively used in a wide variety of agrochemical formulations including growth promoters, insecticides, herbicides and fungicides (Deleu and Paquot, 2004). Beside, their wide ranging implications, synthetic surfactants pose serious environmental and health challenges (Burns et al., 2013). In compliance with current environmental legislation, use of sustainable chemicals in agriculture and agrochemical industries has been considerably evoked. Biosurfactants are among those natural products that have gained substantial scientific attraction due of their potential role in agriculture, pharmaceutical, cosmetics and environmental remediation (Das et al., 2010). Chemically, biosurfactants are characterized as glycolipids, lipopeptides, lipoproteins, lipopolysachrides-protein and polysachrides-protein-fatty acid complexes (Cameotra et al., 2010). Considering the performance of biosurfactants as an alternative to synthetic homologies, they have several advantages, including their high substrate specificity, less toxicity, biodegradability, durability at extreme operational conditions and ease of production using renewable resources (Banat et al., 2010; Silva et al., 2014). Biosurfactants can be produced by wide variety of microorganisms found in different ecological habitats. In soil, production of these biomolecules have been known to facilitate plant-microbe interactions, bioavailability of nutrients for beneficial microbes, elimination of pathogens, and improving soil quality (Sachdev and Cameotra, 2013; Yan et al., 2014). The gylcolipids containing L-rhamnose and βhydroxyalkanoic acid moieties are termed as rhamnolipids (RLs). They are characterized as the most effective class of biosurfactants mainly produced by different strains of Pseudomonas aeruginosa under limited growth conditions (Chen et al., 2007). The physiochemical properties associated with rhamnolipid enable these to be exploited in wide variety of applications. In agriculture, they are very effective in improving the quality of agriculture soil by removing organic and inorganic pollutants (PacwaPlociniczak et al., 2011). Similarly, their excellent antimicrobial activity against variety of plant pathogens engraves a place of themselves as an effective biocontrol agent. Moreover, accumulating information has substantiated its role and efficacy as compared to commercial pesticides for controlling resistant plant pathogens (Sha et al., 2011; Krzyzanowska et al., 2012). Rhamnolipids are also involved in improving plant immunity and growth thus naturally reducing plant infections (Vatsa et al., 2010). Their production in the rhizosphare facilitates establishment of biofilm thereby, improving plant microbe interactions and enhance bioavailability of hydrophobic compounds (Ron and Rosenberg, 2011; Gudina et al., 2015). Pak. J. Agri. Sci., Vol. 53(3),551-556;2016 ISSN (Print) 0552-9034, ISSN (Online) 2076-0906 DOI: 10.21162/PAKJAS/16.1525 http://www.pakjas.com.pk