Aamer Ali Shah | Quaid-i-Azam University, Islamabad, Pakistan (original) (raw)

Papers by Aamer Ali Shah

Microorganisms, 2021

Exopolysaccharide (EPS) has been known to be a good cryoprotective agent for bacteria, but it has... more Exopolysaccharide (EPS) has been known to be a good cryoprotective agent for bacteria, but it has not been tested for cyanobacteria and eukaryotic microalgae. In this study, we used EPS extracted from a glacier bacterium as a cryoprotective agent for the cryopreservation of three unicellular cyanobacteria and two eukaryotic microalgae. Different concentrations of EPS (10%, 15%, and 20%) were tested, and the highest concentration (20%) of EPS yielded the best growth recovery for the algal strains we tested. We also compared EPS with 5% dimethyl sulfoxide (DMSO) and 10% glycerol for the cryopreservation recovery. The growth recovery for the microalgal strains after nine months of cryopreservation was better than 5% DMSO, a well-known cryoprotectant for microalgae. A poor recovery was recorded for all the tested strains with 10% glycerol as a cryoprotective agent. The patterns of growth recovery for most of these strains were similar after 5 days, 15 days, and 9 months of cryopreservat...

Frontiers in Microbiology, 2020

Microbiology Resource Announcements, 2019

Pseudomonas sp. strain BGI-2 is a psychrotrophic bacterium isolated from the ice of Batura Glacie... more Pseudomonas sp. strain BGI-2 is a psychrotrophic bacterium isolated from the ice of Batura Glacier in the Karakoram mountain range. This strain produces a high yield of exopolysaccharide (EPS) at low temperatures and exhibits high freeze-thaw tolerance. The BGI-2 genome contains 11 EPS-producing genes, which are not found in the closely related Pseudomonas strains.

Journal of Cave and Karst Studies, 2016

International Journal of Antimicrobial Agents, 2012

Acinetobacter baumannii is an increasingly important nosoomial pathogen, frequently causing nosoc... more Acinetobacter baumannii is an increasingly important nosoomial pathogen, frequently causing nosocomial outbreaks in ospital Intensive Care Units. Infections caused by multidrugesistant (MDR) bacteria occur worldwide. Furthermore, A. aumannii strains resistant to all antimicrobial agents tested, usceptible only to colistin, are referred to as extensively drugesistant strains and have been detected in South Korea [1]. The purpose of this study was to determine the genetic basis nd molecular epidemiology of MDR A. baumannii isolates and to etermine the clonal relationship amongst A. baumannii clinical solates obtained from Gangwon Province, South Korea. The various olecular determinants of A. baumannii, including carbapenem, ephalosporin, aminoglycoside and quinolone resistance, were nvestigated in this study. Eighty-six strains of non-duplicate A. baumannii were identied by MicroScan WalkAway-96 (Dade Behring, Sacramento, CA) s belonging to Acinetobacter baumannii/haemolyticus from the uniersity hospital laboratory in Gangwon Province from July 2007 to uly 2010. Genomic identification was performed using the amplied ribosomal DNA restriction analysis (ARDRA) method [2]. The xperimental results revealed that all strains tested were A. bauannii. Minimum inhibitory concentrations of clinical antimicrobials or all isolates were determined by the MicroScan WalkAway-96 I system and were interpreted according to Clinical and Laboatory Standards Institute (CLSI) document M100-S19. All of the solates showed resistance to ampicillin, cefazolin, cefotaxime, efotetan, ceftazidime, ceftriaxone, cefuroxime, ciprofloxacin, eropenem, moxifloxacin and ticarcillin/clavulanic acid. Morever, most of A. baumannii isolates showed resistance to cefepime, entamicin, trimethoprim/sulfamethoxazole, tobramycin, aztrenam, amikacin, imipenem and ampicillin/sulbactam. To analyse the production of class B and D carbapenemases, A. aumannii isolates were first screened by a modified Hodge test 3]. All of the A. baumannii isolates showed positive results in the odified Hodge test and negative results in the ethylene diamine etra-acetic acid (EDTA) disk synergy test, indicating the production f class D or another type of carbapenemase. The -lactamases and resistance determinants were detected y multiplex polymerase chain reaction (PCR) [4]. The presence f insertion sequence ISAba1 inserted upstream of blaOXA-23-like nd blaOXA-51-like was sought via PCR using combinations of the SAba1 primers and the OXA-23-like and OXA-51-like reverse rimers [4]. All of the isolates possessed the encoded gene or an intrinsic OXA-51-like carbapenemase and an acquired XA-23-like carbapenemase. ISAba1 inserted upstream of laOXA-23-like was identified in all of the A. baumannii isolates. [ ntimicrobial Agents 39 (2012) 448– 454

Applied Microbiology and Biotechnology, 2014

Alteromonas sp. GNUM-1 is known to degrade agar, the main cell wall component of red macroalgae, ... more Alteromonas sp. GNUM-1 is known to degrade agar, the main cell wall component of red macroalgae, for their growth. A putative agarase gene (agaG1) was identified from the mini-library of GNUM-1, when extracellular agarase activity was detected in a bacterial transformant. The nucleotide sequence revealed that AgaG1 had significant homology to GH16 agarases. agaG1 encodes a primary translation product (34.7 kDa) of 301 amino acids, including a 19-amino-acid signal peptide. For intracellular expression, a gene fragment encoding only the mature form (282 amino acids) was cloned into pGEX-5X-1 in Escherichia coli, where AgaG1 was expressed as a fusion protein with GST attached to its N-terminal (GST-AgaG1). GST-AgaG1 purified on a glutathione sepharose column had an apparent molecular weight of 59 kDa on SDS-PAGE, and this weight matched with the estimated molecular weight (58.7 kDa). The agarase activity of the purified protein was confirmed by the zymogram assay. GST-AgaG1 could hydrolyze the artificial chromogenic substrate, p-nitrophenyl-β-D-galactopyranoside but not p-nitrophenyl-α-D-galactopyranoside. The optimum pH and temperature for GST-AgaG1 activity were identified as 7.0 and 40 °C, respectively. GST-AgaG1 was stable up to 40 °C (100 %), and it retained more than 70 % of its initial activity at 45 °C after heat treatment for 30 min. The K m and V max for agarose were 3.74 mg/ml and 23.8 U/mg, respectively. GST-AgaG1 did not require metal ions for its activity. Thin layer chromatography analysis, mass spectrometry, and (13)C-nuclear magnetic resonance spectrometry of the GST-AgaG1 hydrolysis products revealed that GST-AgaG1 is an endo-type β-agarase that hydrolyzes agarose and neoagarotetraose into neoagarobiose.

Environmental Pollution, 2017

Pseudomonas aeruginosa and Sphinogobacterium sp. are well known for their ability to decontaminat... more Pseudomonas aeruginosa and Sphinogobacterium sp. are well known for their ability to decontaminate many environmental pollutants like PAHs, dyes, pesticides and plastics. The present study reports the annotation of genomes from P. aeruginosa and Sphinogobacterium sp. that were isolated from compost, based on their ability to degrade poly(lactic acid), PLA, at mesophillic temperatures (~30°C). Draft genomes of both the strains were assembled from Illumina reads, annotated and viewed with an aim of gaining insight into the genetic elements involved in degradation of PLA. The draft-assembled genome of strain Sphinogobacterium strain S2 was 5,604,691 bp in length with 435 contigs (maximum length of 434,971 bp) and an average G+C content of 43.5%. The assembled genome of P. aeruginosa strain S3 was 6,631,638 bp long with 303 contigs (maximum contig length of 659,181 bp) and an average G+C content 66.17 %. A total of 5,385 (60% with annotation) and 6,437 (80% with annotation) protein-codi...

Enzyme and Microbial Technology, 2006

Lipases are a class of enzymes which catalyse the hydrolysis of long chain triglycerides. Microbi... more Lipases are a class of enzymes which catalyse the hydrolysis of long chain triglycerides. Microbial lipases are currently receiving much attention with the rapid development of enzyme technology. Lipases constitute the most important group of biocatalysts for biotechnological applications. This review describes various industrial applications of microbial lipases in the detergent, food, flavour industry, biocatalytic resolution of pharmaceuticals, esters and amino acid derivatives, making of fine chemicals, agrochemicals, use as biosensor, bioremediation and cosmetics and perfumery.

Critical Reviews in Microbiology, 2004

... Address correspondence to AA Shah, Microbiology Research Lab, Department of Biological Scienc... more ... Address correspondence to AA Shah, Microbiology Research Lab, Department of Biological Science, Quaid-i-Azam University, Islamabad Pakistan. ... spectrum beta-lactamase (ESBL)-producing organisms pose unique challenges to clinical micro-biologists, clinicians ...

Biotechnology Advances, 2008

Lack of degradability and the closing of landfill sites as well as growing water and land polluti... more Lack of degradability and the closing of landfill sites as well as growing water and land pollution problems have led to concern about plastics. With the excessive use of plastics and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years. Awareness of the waste problem and its impact on the environment has awakened new interest in the area of degradable polymers. The interest in environmental issues is growing and there are increasing demands to develop material which do not burden the environment significantly. Biodegradation is necessary for water-soluble or water-immiscible polymers because they eventually enter streams which can neither be recycled nor incinerated. It is important to consider the microbial degradation of natural and synthetic polymers in order to understand what is necessary for biodegradation and the mechanisms involved. This requires understanding of the interactions between materials and microorganisms and the biochemical changes involved. Widespread studies on the biodegradation of plastics have been carried out in order to overcome the environmental problems associated with synthetic plastic waste. This paper reviews the current research on the biodegradation of biodegradable and also the conventional synthetic plastics and also use of various techniques for the analysis of degradation in vitro.

Annals of Microbiology, 2007

Streptoverticillium kashmirense AF1 with the ability to degrade a natural polymer, poly(3-hydroxy... more Streptoverticillium kashmirense AF1 with the ability to degrade a natural polymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was isolated from municipal sewage sludge by soil burial technique. The PHBV film was degraded by the action of extracellular enzymes secreted by the microorganisms. Degradation of PHBV was evident by the formation of clear zones of hydrolysis on the polymer containing mineral salt agar plates. The extent of PHBV degradation increased up to 30 days of incubation. Maximum production of PHBV depolymerase was observed both at pH 8 and pH 7, 45 °C, 1% substrate concentration and in the presence of lactose as an additional carbon source. Two types of extracellular PHBV depolymerases were purified fromS. kashmirense AF1 by gel permeation chromatography using Sephadex G-75. The molecular weights of the two proteins were found to be 35 and 45 kDa approximately, as determined by SDS-PAGE. The results of the Sturm test also showed more CO2 production as a result of PHBV degradation, in the test as compared to control. The present findings indicated the degradation capabilities ofS. kashmirense AF1.

Bacillus subtilis BS1 was used in the present study for the production of protease. For protease ... more Bacillus subtilis BS1 was used in the present study for the production of protease. For protease production optimum pH and temperature were found to be 11 and 50˚C, respectively. Soybean (197 PU/mg) and casein (168 PU/mg) proved as the best substrates for the production of enzyme. Maximum production of protease (126 and 121 PU/mg) was shown in 1.5 and 4.5% of Sodium chloride (NaCl) concentration, respectively. Maximum activity was observed at pH 9 at 90ºC, in crude extract, after 20 minutes of incubation. EDTA slightly enhanced proteolytic activity, whereas, Na, K, Ca, Li, Mg, Cu and Fe inhibited the activity of protease. Due to maximum production of protease in the presence of cheaper, low concentrations of substrate and stability at alkaline pH, high temperature and salt-tolerance, these characteristics makes the strain and its enzymes usefull in different industries.

International Biodeterioration & Biodegradation, 2010

ABSTRACT The purpose of this study was to isolate the poly (3-hydroxybutyrate-co-3-hydroxyvalerat... more ABSTRACT The purpose of this study was to isolate the poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) degrading microorganisms from soil, and the analysis of degradation by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. After soil burial for 120 days at 37 °C, a new actinobacterial strain, Actinomadura sp. AF-555, was isolated from the surface of PHBV film, through an enrichment technique. The increase in biomass on the surface of PHBV film pieces and in the medium after culturing in basal salt medium indicated that it utilizes PHBV as a source of carbon and energy. Scanning electron microscopy of PHBV film at the end of incubation showed many changes in surface morphology, such as erosion and extensive roughening of the surface with pit formation, as compared to the untreated plastic pieces. The FTIR spectra of PHBV film showed a decrease in the peak from 1725 cm−1 (untreated plastic film) to 1721 cm−1, and disappearance of a peak present in controls, at 2745 cm−1, indicating the breakdown of ester (>CO) or O–R groups and –C–H bonds, respectively. The intensity of the band at 1185 cm−1, the amorphous state-sensitive band, increased, indicating an increase in 3HV content. It can be concluded that soil contains microorganisms that can potentially be used for biodegradation of plastic wastes.

Three psychrotrophic bacteria, morpho-physiologically, identified as Bacillus subtilis MRLBA7, Ba... more Three psychrotrophic bacteria, morpho-physiologically, identified as Bacillus subtilis MRLBA7, Bacillus licheniformis MRLBA8 and Bacillus megaterium MRLBA9 were isolated from -20°C freezer of the Microbiology Research Laboratory (MRL), Quaid-i-Azam University, Islamabad, Pakistan. These strains were able to grow aerobically at 6°C but not at 40°C except MRLBA8 that could grow at 48°C. None of the isolates showed inhibition of growth in the presence of glycerol. Isolate MRLBA7, bearing central spore, grew in the presence of 30% glycerol at 0°C after 48 h of incubation and showed maximum growth without glycerol at 25°C after 24 h. Isolate MRLBA8 showed growth in the presence of 50% glycerol at 4°C after 72 h of incubation and maximum growth was observed at 20°C in the absence of glycerol. Isolate MRLBA9 showed growth at 6°C in the presence of 40% glycerol after 48 h of incubation and maximum growth was observed at 25°C in the absence of glycerol. Isolates were susceptible to antibiotics except Bacillus subtilis MRLBA7 that exhibited antibiotic resistance against penicillin and fosphomycin, Bacillus licheniformis MRLBA8 against aztreonam and fosphomycin, and Bacillus megaterium MRLBA9 against vancomycin and penicillin. The growth profile and biochemical characteristics of all the isolates were rather similar to that of mesophilic counterparts except adaptation to low temperature. These strains could be used as model microbial strains for characterization of food contaminants in freezers, to understand the mechanism of antibiotic resistance induced at low temperature and as a source of psychrotrophic enzymes.

Research in Microbiology, 2004

β-Lactam antimicrobial agents represent the most common treatment for bacterial infections and co... more β-Lactam antimicrobial agents represent the most common treatment for bacterial infections and continue to be the leading cause of resistance to β-lactam antibiotics among Gram-negative bacteria worldwide. The persistent exposure of bacterial strains to a multitude of β-lactams has induced dynamic and continuous production and mutation of β-lactamases in these bacteria, expanding their activity even against the newly developed β-lactam antibiotics. These enzymes are known as extended-spectrum β-lactamases (ESBLs). The majority of ESBLs are derived from the widespread broad-spectrum β-lactamases TEM-1 and SHV-1. There are also new families of ESBLs, including the CTX-M and OXA-type enzymes as well as novel unrelated β-lactamases. In recent years, there has been an increased incidence and prevalence of ESBLs. ESBLs are mainly found in strains of Escherichia coli and Klebsiella pneumoniae but have also been reported in other Enterobacteriaceae strains and Pseudomonas aeruginosa. Infections with ESBL-producing bacterial strains are encountered singly or in outbreaks, especially in critical care units in hospitals, resulting in increasing cost of treatment and prolonged hospital stays. Not only may nursing home patients be an important reservoir of ESBL-containing multiple antibiotic-resistant organisms, but ambulatory patients with chronic conditions may also harbor ESBL-producing organisms.  2004 Elsevier SAS. All rights reserved. (A.A. Shah).

Annals of Microbiology, 2006

Lipases are a class of enzymes, which catalyse the hydrolysis of long chain triglycerides. Microb... more Lipases are a class of enzymes, which catalyse the hydrolysis of long chain triglycerides. Microbial lipases are currently receiving much attention with the rapid development of enzyme technology. Lipases have industrial potential in the chemical, pharmaceutical, medical, cosmetic, leather and paper manufacturing industries, biosurfactant synthesis, and agrochemicals. ABacillus strain isolated from soil was tested for the production of extracellular lipase, by batch culturing in shake flask. The growth conditions were optimised for the maximum production of enzyme. Various parameters for the production of lipase, such as temperature, incubation period, pH, carbon source, nitrogen source and lipids were studied. Maximum lipase production was found in 48-h-old culture filtrate at 37 °C, pH 8.0. Among all the carbon sources, salicin gave the maximum activity and among all the nitrogen sources yeast extract gave maximum production/activity. Tween (20 and 80) does not stimulate the growth much but assisted in enzyme production.

International Biodeterioration & Biodegradation, 2007

The contribution of bacteria, isolated from sewage sludge, towards the microbial degradation of p... more The contribution of bacteria, isolated from sewage sludge, towards the microbial degradation of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was studied. A microbial consortium was inoculated on mineral salt agar plates containing different concentrations of PHBV as ...

Annals of Microbiology, 2008

The present study describes the isolation of bacteria from soil with the ability to degrade plast... more The present study describes the isolation of bacteria from soil with the ability to degrade plastic polyurethane (PU). Bacterial strains attached on the polyurethane film, after soil burial for 6 months, were isolated and identified asBacillus sp. AF8,Pseudomonas sp AF9,Micrococcus sp. 10,Arthrobacter sp. AF11, andCorynebacterium sp. AF12. In plate assay, zones of hydrolysis were visualised around the bacterial colonies on mineral salt agar plates containing polyurethane as a sole carbon source. The results of the Sturm test for degradability showed more CO2 production in the test than in control. The production of esterase was detected in the presence of polyurethane as a substrate. The Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy showed certain changes on the surface of PU film and formation of some new intermediate products after polymer breakdown.