جستجوی مقالات مرتبط با کلیدواژه « فلور باکتریایی » در نشریات گروه « زیست شناسی »

Background &

Dental plaque is structurally and functionally a biofilm that may lead to caries and root infection due to disruption of microbial homeostasis. The present research aimed to investigate the molecular characteristics of dental flora of patients in East Tehran.Materials &

In this cross-sectional study, 9 samples of dental plaque, caries, and root canal from five patients who were randomly selected in 2017 were collected under sterile  conditions. Bacteria were cultured using the standard BHI broth culture medium. General primers of the 16S rRNA gene were used for molecular identification of bacteria and investigation of their phylogenetic relationships. Demographic characteristics of the subjects were also examined.

Thirteen bacterial isolates were identified from clinical specimens of plaque and tooth decay. The isolated bacteria belonged to three phyla, five families, six genera Arthrobacter, Brevundimonas, Granulicatella, Kocuria, Neisseria, and Streptococcus, as well as seven species. The most abundant isolates were N. perflava (n=5) and S. salivarius (n=3). The identified bacteria were arranged in four branches of a phylogenetic tree. No association was found between bacteria and demographic characteristics.

Identifying the factors involved in dental infections is an effective approach to prevention. In this study, 11 bacterial isolates from dental plaque and 2 bacterial isolates from tooth decay were identified and no strains from the root specimens were identified. The  discrepancy between plaque bacteria and caries may be due to the small sample size and  microbiological methods used.

 In this study, in order to investigate the antibacterial properties of silver nanoparticles that were synthesized using Sargassum seaweed extract by biological extracellular method, Mesophile Enterobacteriaceae, lactic acid bacteria and psychrophilic bacteria skin of common carp exposed to three concentration (0.11, 1.13, 5.67 mg/L AgNP) of this silver nanoparticles were studied for 14 days. The results showed that with increasing concentration of silver nanoparticles, the load of Enterobacteriaceae and Mesophile significantly reduced compared with control (p0.05). The lowest bacterial count was related to enterobacteria (log cfu/cm2 1.00±0.01), when exposed to concentration 1.13 mg/L AgNP. Lactic acid bacteria in all treatments and in control, did not grow until the last day of exposure.

Inroduction & Organic acids product such as Apple cider vinegar usually alter or reduce bacteria within the gastrointestinal tract and decrease pH in the intestinal tract, thus inhibit the growth of harmful bacteria the host animal. The objectives of this study, was to evaluate the effect of dietary supplementation of Apple cider vinegar on total hemocyte count, histology of the hepatopancreas and intestinal microbiota of the Litopenaeus vannamei.
In this study two hundred twenty-five Litopenaeus vannamei with an average initial weight of 10.2 ± 0.04 g, that they were fed diets supplemented with different levels of a Apple cider vingar after 60 days. Treatments included levels of 0, 2% and 4% Apple cider vinegar diets. Shrimp were randomly sampled at the end of the experiment. The hemolymph was withdrawn from abdominal segments of samples for measuring total hemocyte count. The number of the B-cells and R-cells, as well as tubule diameter were quantified for histological examination. Also, the gut microbial fora count (log CFU g-¹) was determined using nutrient agar medium plus salt.
The results indicated that, shrimp fed Apple cider vinegar diets had significantly higher total hemocyte count (p 0.05), whereas the number of the resorptive cells significantly decreased in shrimp fed a diet containing Apple cider vinegar and a dramatic decrease was observed in 2% Apple cider vinegar treatment (p This study was the first reported data on the use of dietary Apple cider vinegar in aquatic animal. These findings indicate that the Apple cider vinegar was introducing suitable organic acid alternative and also it has the greatest potential for use as a diet supplement for L. vannamei.

German Cockroaches (Blattela germanica) are insects that often live in dirty environment such as sewagesand toilets and feed from contaminatedmaterials.This insect is one of the most important factors to transport and spread bacteria in human environment, particularlybacteria of Enterobacteriaceae family. In this study, German cockroach's midget’s bacterial flora in Tehran was identified. German cockroaches from various regions of Tehran were round up and their gut were extracted and cultured on microbial media. Grown samples identified with differentculture media.Ten bacterial genera were identified in cockroach's midgut. Nine genera were belonging to gram negative bacteria and one isolates belong to gram positive bacteria. These genera belong to Citrobacter (20%), Psedomonas (18%), Proteus (17%), E. coli (15.5%), Enterobacter (12%), Staphilococcus (11.1%), Salmonella (3.3%), Klebsiella (1.1%), Shigella and Hafnia (1%). Several pathogenicbacteria are growing within the body of German cockroach and transmittedto the human environment with these insects. Most of these bacteria are pathogenic and can effect on human health. In this study, the most of identified bacteria were belong to Enterobacteriaceae family, and could be pathogen and effective on human hygiene.

Silver Nanoparticles included 56 % of total manufactured Nanomaterials due to its anti-bacterial properties in the world. Therefore، the release of Silver Nanoparticles to water ecosystems will make an irreparable damage to biota، especially to natural bacterial flora. The purpose of this study is to investigate the Silver Nanoparticles effects on the bacterial flora of rainbow trout skin. To ensure the quality of the Silver Nanoparticles، the ICP، Zetasizer، TEM، EDX، and Uv-vis Spectrophotometer sets were used. Also، the population’s mesophilic bacteria، psychrophile، Enterobacteriaceae and Lactic acid bacteria (LAB) of skin after 14 days kept of fish in 1، 0. 1 and control group of Silver Nanoparticle concentrations were counted by pour plate method. Results of the study showed that the fish skin LAB bacteria decreased significantly with the increase of Silver Nanoparticle concentration and mesophile and Enterobacteriaceae were less affected. Whereas، population of fish skin psychrophile bacteria significantly increased with enhancing of Silver Nanoparticles concentration. Analysis of result suggested that according to the type of studied group of bacteria، an antibacterial property of Silver Nanoparticles is selective and different.