Natural Science and Public Health

A study was conducted on filamentous bacteria implicated in bulking and foaming problems in activated sludge process of sewage treatment plant in Dubai, United Arab Emirates over a period of six months. To determine morphological characteristics of diverse filaments, foam and mixed liquor samples were collected and studied using various simple and differential staining techniques. Fluorescent in situ hybridization analysis was carried out in mixed liquor samples with nocardioform group specific probes using VIT kit (Vermicon Identification Technology, Vermicon, Munich). The dominant filamentous bacteria identified from mixed liquor and foam samples included: A long branched form of Gram varibale nocardioform actinomycetes species, Thiothrix, Eikelboom Type 021N, Sphaerotilus natans, Beggiatoa and Nostocoida limicola type I. Occasionally attached growth forms of Eikelboom type 0041/0675 like filaments were observed in mixed liquor and foam samples especially during warm weather. All ...

In this study, the bacterial diversity in the activated sludge system of a full-scale municipal wastewater treatment plant in Dubai was monitored over a period of one year using ribosomal RNA (rRNA) targeted oligonucleotide probes for a defined phylogenetic group of bacteria by the Fluorescence in situ hybridization (FISH) technique. The largest fraction of the bacterial community in the sludge samples belonged to the gamma-subgroup of proteobacteria (25%) followed by gram positive bacteria of high G+C content(16%), gram positive bacteria with low G+C content (9 %), beta-proteobacteria (8%) and alpha-proteobacteria(5 %) with respect to the population percentages stained by DAPI (4,6-diamino-2-phenylindole).A specific nocardioform actinomycete, simultaneously targeted by both HGC69a and MNP1 probes, was predominantly found throughout the study period in all activated sludge mixed liquor samples. The nocardioform actinomycetes group members were detected in both branched and single ce...

Extended-spectrum beta-lactamase (ESBL) producing bacteria of the Enterobacteriaceae family are a significant threat to public health, posing a challenge for health authorities worldwide. In the UAE, very little information is available about ESBL producing bacteria from non-clinical sources. In this study, 206 pure cultures belonging to the Enterobacteriaceae family were isolated from food and wastewater sources in Dubai, UAE. All the isolates were tested against third-generation cephalosporin antibiotics by the disc diffusion method and screened on ESBL chromogenic agar. Among all isolates (n = 86), 41.7% were potential ESBL producers belonging to E. coli, Klebsiella, Enterobacter, Shigella, and Citrobacter (KESC group), and Proteus. Of all the potential ESBL producing isolates, 19 (22%) were confirmed as ESBL producers by a double-disc diffusion test with the fourth generation cephalosporin–Cefpirome. The multiplex polymerase chain reaction was used for the detection of ESBL bla ...

Quantum dots (QDs) or nanocrystals 5 to 50 nm in size have recently emerged as a novel and promising class of fluorophores for cellular imaging. Unlike conventional organic dyes, QDs can be excited by a wide spectrum of wavelengths to give enhanced photostability, and their emission spectra, which differ according to size and material composition, are narrow, symmetrical, and tunable. This novel detection strategy can significantly improve the efficiency of molecular techniques used in the identification of important microbes related to human diseases. The aim of this study was to apply QDs linked antibodies to detect pathogenic Salmonella typhimurium cells. The signal, photostabilty and efficiency of QDs linked antibodies was compared with the organic fluorophore linked antibody for the detection of Salmonella cells. The use of QDs as fluorophores has shown greater enhancement in photostability and brighter signal than conven-tional organic dyes in detecting S. typhimurium cells. T...

Anaerobic digestion for methane production comprises of an exceptionally diverse microbial consortium, a profound understanding about which is still constrained. In this study, the methanogenic archaeal communities in three full-scale anaerobic digesters of a Municipal Wastewater Treatment Plant were analyzed by Fluorescence hybridization and quantitative real-time Polymerase Chain Reaction (qPCR) technique. Fluorescence hybridization (FISH) was performed to detect and quantify the methanogenic in the sludge samples whereas qPCR was carried out to support the FISH analysis. Multiple probes targeting domain archaea, different orders and families of Archaea were used for the studies. In general, the aceticlastic organisms were more abundant than the hydrogenotrophic organisms . Both FISH and qPCR indicated that family was the most abundant suggesting that aceticlastic methanogenesis is probably the dominant methane production pathway in these digesters. Future work involving high-thro...

Background: Cross-contamination of foodborne pathogens from undercooked poultry meat to ready-to-eat food has been shown to be responsible for a number of foodborne disease outbreaks. Various studies have indicated that bacterial cross-contamination occurs during food preparation where bacteria present on food contact other surfaces and cause illness.Objectives: This study evaluated the ability of bacteria to survive and cross-contaminate other foods during the preparation of fresh chicken. Salmonella spp. cross-contamination from chicken to cucumber and utensils under various food handling scenarios was determined.Methods: Two scenarios were tested: in scenario 1, cutting board and knife used for cutting chicken without washing step were sampled.  In scenario 2, cutting board and knife was washed with tap water separately after cutting chicken, and subsequently used for cutting cucumber.  In scenario 1, chicken, cutting board, knife, and hands were sampled, and in scenario 2, cucum...

Extended-spectrum beta-lactamase (ESBL) producing bacteria of the Enterobacteriaceae family are a significant threat to public health, posing a challenge for health authorities worldwide. In the UAE, very little information is available about ESBL producing bacteria from non-clinical sources. In this study, 206 pure cultures belonging to the Enterobacteriaceae family were isolated from food and wastewater sources in Dubai, UAE. All the isolates were tested against third-generation cephalosporin antibiotics by the disc diffusion method and screened on ESBL chromogenic agar. Among all isolates (n = 86), 41.7% were potential ESBL producers belonging to E. coli, Klebsiella, Enterobacter, Shigella, and Citrobacter (KESC group), and Proteus. Of all the potential ESBL producing isolates, 19 (22%) were confirmed as ESBL producers by a double-disc diffusion test with the fourth generation cephalosporin–Cefpirome. The multiplex polymerase chain reaction was used for the detection of ESBL bla ...

This study aimed at isolating filamentous bacteria from the activated sludge samples of a full- scale municipal wastewater treatment plant in Dubai and studying their physiological and biochemical characteristics. Fluorescent in situ hybridization technique (FISH) was applied to identify filamentous bacteria pure culture isolates. In total, sixteen filamentous bacteria were successfully isolated and maintained on various culture media. Ten gram positive filamentous bacteria were successfully identified as nocardioform actinomycete using nocardioform group specific probes in FISH analysis. Most of the isolates were shown to utilize different carbon sources like glycerol, maltose, fructose etc. The optimum growth of most of the isolates was found to be at 27° C and neutral pH, however a few isolates were able to grow at 47° C and acidic pH. Overall results indicate that filamentous bacteria isolated in this study were quite diverse in their physiological and biochemical characteristic...

The objective of this study was to isolate and verify the sensitivity to antimicrobial agents of strains of Salmonella spp. isolated from chicken meat samples in Dubai, United Arab Emirates. A total number of 60 fresh chicken meat samples mainly chicken breast, chicken wing and chicken thigh were randomly collected from various supermarkets and butcheries in Dubai. The methods for Salmonella isolation and characterisation along with the susceptibility of these isolates to antibiotics were assessed. In total 66 pure isolates of Salmonella were obtained. The genus level identification of these isolates was carried out by Fluorescence In Situ Hybridisation (FISH) using the VIT-Salmonella kit (Vermicon Identification Technology, Vermicon, Munich, Germany). All the isolates tested positive for Salmonella genus specific oligonucleotide probe. These isolates were then subjected to antimicrobial susceptibility testing to 10 commonly used antibiotics. All the isolates (100%) showed resistanc...