A novel DNA based bioassay toward ultrasensitive detection of Brucella using gold nanoparticles supported histidine: A new platform for the assay of bacteria in the cultured and human biofluids with and without polymerase chain reactions (PCR).

Brucella organisms, which are small aerobic intracellular coccobacilli, localize in the reproductive organs of host animals, causing abortions and sterility. In this work, we used a novel method to preparation of excellent genosensor on the surface of low-toxic substrate (gold nanoparticles) supported histidine prepared by fully electrodeposition method. The results of the present work show that the nano-Au-Hist provide suitable active sites for the DNA probe immobilization. The fabricated DNA genosensor employs cyclic voltammetry (CV), and square wave voltammetry (SWV) techniques for monitoring the behavior of the redox probe. To survey the morphological pattern and surface structural characterizations, the Field Emission-Scanning Electron Microscopy (FE-SEM) has been applied. In summary, the gold nanoparticles supported by histidine was checked for immobilization of a Brucella-specific probe and detection of hybridization with a variety of sequences with a high sensitivity. The high sensitivity would be related to more favorable conformation and deflection angle of the probe for an efficient hybridization, higher surface concentration of the probe, and/or enhanced diffusion regime. These lead to better display of the entangled target sequences arising from the nanobiotechnology. The proposed genosensor showed a perfect distinction between complementary, non-complementary and mismatched DNA sequences. The engineered genosensor for detection of the complementary/non-complementary sequences were assayed. The fabricated genosensor was evaluated for the assay of the bacteria in the cultured and human samples with and without polymerase chain reactions (PCR). The genosensor could detect the complementary sequence in linear concentration range of 1 × 10-1 to 1 × 10-10 µM, and a low limit of quantification 0.1 pM.

Biodegradation of Para Amino Acetanilide by Halomonas sp. TBZ3.

BACKGROUND: Aromatic compounds are known as a group of highly persistent environmental pollutants. Halomonas sp. TBZ3 was isolated from the highly salty Urmia Lake of Iran. In this study, characterization of a new Halomonas isolate called Halomonas sp. TBZ3 and its employment for biodegradation of para-amino acetanilide (PAA), as an aromatic environmental pollutant, is described. OBJECTIVES: This study aimed to characterize the TBZ3 isolate and to elucidate its ability as a biodegradative agent that decomposes PAA. MATERIALS AND METHODS: Primarily, DNA-DNA hybridization between TBZ3, Halomonas denitrificans DSM18045T and Halomonas saccharevitans LMG 23976T was carried out. Para-amino acetanilide biodegradation was assessed using spectrophotometry and confirmed by gas chromatography-mass spectroscopy (GC-MS). Parameters effective on biodegradation of PAA were optimized by the Response Surface Methodology (RSM). RESULTS: The DNA-DNA hybridization experiments between isolate TBZ3, H. denitrificans and H. saccharevitans revealed relatedness levels of 57% and 65%, respectively. According to GC-MS results, TBZ3 degrades PAA to benzene, hexyl butanoate, 3-methyl-1-heptanol and hexyl hexanoate. Temperature 32.92°C, pH 6.76, and salinity 14% are the optimum conditions for biodegradation with a confidence level of 95% (at level α = 0.05). CONCLUSIONS: According to our results, Halomonas sp. TBZ3 could be considered as a biological agent for bioremediation of PAA and possibly other similar aromatic compounds.