A stable dark variant separated from photobacterium phosphoreum (A2) was fixed in agar-gel membrane and immobilized onto an exposed end of a fiber-optic linked with bioluminometer. The variant could emit a luminescent signal in the presence of genotoxic agents, such as Mitomycin C (MC). The performance of this whole-cell optical fiber sensor system was examined as a function of several parameters, including gel probe thickness, bacterial cell density, and diameter of the fiber-optic core and working temperature. An optimal response to a model genotoxicant, Mitomycin C, was achieved with agar-bacterial gel membrane: the thickness of gel membrane was about 5 mm; the cell density of bacteria in gel membrane was about 2.0 x 10(7)/ml; the diameter of fiber-optic core was 5.0 mm; the working temperature was 25 degrees C. Under these optimized conditions, the response time was less than 10 h to Mitomycin C, with a lower detection threshold of 0.1 mg/L.
Biosensing Techniques ; Chemiluminescent Measurements ; Fiber Optics ; Luminescent Proteins/*genetics ; Mitomycin/*pharmacology ; Mitomycin/toxicity ; Photobacterium/*genetics ; Transcription, Genetic/drug effects ; Variation (Genetics)

Objective To understand the prevalence of Cryptosporidium infection in diarrhea infants under 2 years old in Wuhan City,so as to provide the epidemiological evidence for the prevention and treatment of cryptosporidiosis. Methods The fecal samples from infants under 2 years old with diarrhea were collected in Hubei General Hospital and Central South Hospital in Wuhan City,Hubei Province from August 2014 to July 2015. The fecal samples were stored in 2.5%potassium dichromate at 4℃after filtered. The DNA was extracted from the fecal pellets with the phenol-chloroform method. The Cryptosporidium species were detected by a nested PCR assay targeting the SSU rRNA gene of the parasite. All the positive PCR products were sequenced on ABI 3100 automated sequencer,and the amplified sequences were compared to homologous sequences in the NCBI database by using the Basic Local Alignment Search Tool(BLAST). Phylogenetic analyses were performed by using the software MEGA (version 4.0)based on the Neighbour-Joining method. Results The human stool specimens(n=298)were screened for the presence of Cryptosporidium by nested PCR. The infection rate of Cryptosporidium was 3.02%(9/298). The infection rate of Cryp-tosporidium was 5.93%(7/118)in the infants between 1-2 years old,and the infection rate was 1.11%(2/180)in the infants un-der 1 year old,and there was a significant difference between the two groups(χ2 =4.13,P<0.05). The nine samples which were positive by nested PCR were successfully sequenced and compared with the reference sequences in GenBank. The results revealed the nine positive specimens were all infected with C. parvum,and two of them were co-infected with C. hominis. Neigh-bor-joining trees were constructed from the aligned partial SSU rRNA sequences of these nine isolates,and in the SSU rRNA lo-cus,the nine isolates were grouped with C. parvum. Conclusion There exists Cryptosporidium infection in the infants under 2 years old with diarrhea in Wuhan City,and the main species of Cryptosporidium is C. parvum.

A stable dark variant separated from photobacterium phosphoreum (A2) was fixed in agar-gel membrane and immobilized onto an exposed end of a fiber-optic linked with bioluminometer. The variant could emit a luminescent signal in the presence of genotoxic agents, such as Mitomycin C (MC). The performance of this whole-cell optical fiber sensor system was examined as a function of several parameters, including gel probe thickness, bacterial cell density, and diameter of the fiber-optic core and working temperature. An optimal response to a model genotoxicant, Mitomycin C, was achieved with agar-bacterial gel membrane: the thickness of gel membrane was about 5 mm; the cell density of bacteria in gel membrane was about 2.0 x 10(7)/ml; the diameter of fiber-optic core was 5.0 mm; the working temperature was 25 degrees C. Under these optimized conditions, the response time was less than 10 h to Mitomycin C, with a lower detection threshold of 0.1 mg/L.
Biosensing Techniques ; Fiber Optic Technology ; Genetic Variation ; Luminescent Measurements ; Luminescent Proteins ; genetics ; Mitomycin ; pharmacology ; toxicity ; Optical Fibers ; Photobacterium ; genetics ; Transcription, Genetic ; drug effects