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<abstract> <p>Last cholera epidemic has been recorded in Bangladesh between 1992–1993, while few sporadic localized outbreaks have been reported as recent as 2005. Serotype O1 of <italic>Vibrio cholera</italic> is considered as the principal causative agent which transmits through contaminated drinking water resulting that epidemic. Therefore, the objective of this research was to isolate <italic>V. cholera</italic> in 3 different water sources; River, pond and tube-well, in 5 different locations of Gazipur, Bangladesh, and to analyze their antibiogram study. A total of 45 water samples were randomly collected for the isolation and identification of <italic>Vibrio</italic> spp. Samples are then serially diluted in alkaline peptone water and streak on Thiosulfate Citrate Bile Salt Sucrose-TCBS agar for quantification of <italic>V</italic>. spp. For <italic>V. cholera</italic> isolation water samples were first enriched in nutrient broth at 37 °C for 16 hours followed by cultivation in selective media; TCBS agar at 37 °C for 24 hours. Yellow colonies on TCBS agar were screed as <italic>V. cholera</italic> and was confirmed by analyzing their biochemical characteristics like Catalase, Oxidase, MR, VP, Indole, Sugar fermentation. Following isolation antibiotic sensitivity test was performed on each <italic>V. cholera</italic> isolates to determine their antibiotic sensitivity profile. The results showed, out of 45 samples 12 contained <italic>V. cholera</italic>. Tube-well water has significantly lower concentration (log CFU/mL) of <italic>V</italic>. spp. than river and pond water (P &lt; 0.05). Bacterial concentration doesn't deviate (P &gt; 0.05) significantly in 5 different location the sample was collected from. All the 12 isolates were sensitive to Gentamicin and ciprofloxacin (100%), while Chloramphenicol (91.67%), Sulfamethoxazole (91.67%), Azithromycin (66.67%) showed high sensitivity. Isolates showed marginal sensitivity towards Tetracycline (33.33%), and Cephalexin (16.67%) and 100% resistance against antibiotics like Vancomycin, Penicillin, Erythromycin, and Nalidixic Acid. Based on these data we recommend using tube-well water instead of river and pond water for drinking purposes. Furthermore, we suggest selective use of sensitive antimicrobials listed here for therapeutics of cholera outbreak.</p> </abstract>

Previously, we identified 49 undeletable chromosomal regions harboring only non-essential genes in the genome of Saccharomyces cerevisiae. We proposed that there might be unknown synthetic lethal combinations of genes present in such undeletable regions of the genome. In this study, we chose four of the smallest undeletable chromosomal regions among the 49 and performed extensive further analyses to narrow down the gene-pairs responsible for lethality by replacing sub-regions in various combinations with a DNA module comprising the CgLEU2 marker. Although the methodology was different from previous study, interestingly the results revealed that not only the subregions but also the entire region was replaceable. To solve the apparent discrepancy between previous and present results, we further conducted additional analysis including investigation of suppressor mutation and mini-chromosome loss assay through the construction of mini-chromosome harboring two particular chromosomal regions with marked with URA3 marker by employing 5-FOA system. Based upon careful observation on the phenotype of colony formation on 5-FOA medium by spot test, we came to an important conclusion that particular chromosomal regions harboring only non-essential genes can be categorized into three classes, i.e., essential, non-essential and intrinsically essential. Intrinsically essential region is defined as appearance of papillae after mini-chromosome loss which implicates that the region is essential but compensatable against cell lethality. Our present study indicates that prudent and multiple approaches as performed in this study are needed to judge whether a particular chromosomal region of the S. cerevisiae genome is essential, non-essential or intrinsically essential but compensatable.