Escherichia coli is the species of the genus Escherichia with the greatest epidemiological impact. Escherichia coli infections are found mainly in places with poor hygiene; the infants with ages between 1 and 3 years old are included in the category with the highest risk. It is a "fecal-oral" transmission mechanism as a result of consumption of contaminated food or water, or by "dirty hands". The foods most commonly implicated in the transmission of the infection are unpasteurized milk and milk products, beef, especially the one insufficiently cooked, unpasteurized fruit juice, lettuce and insufficiently washed vegetables. The disease has been reported worldwide, being described numerous episodes of infection with Escherichia coli that caused multiple illnesses and deaths. Escherichia coli has three types of antigens: antigen "O" (somatic), antigen "H" (flagella) and antigen "K" (capsular). Clinical manifestations are present in the form of non-specific diarrhea, a dysentery form of enteritis, choleriform enteritis, hemorrhagic colitis and hemolytic uremic syndrome (HUS). The Escherichia coli infection diagnosis is made by identifying the etiologic agent and/or by highlighting the VTI toxin in the feces. The treatment consists in precautionary antibiotherapy, hydrodynamics and electrolyte rebalancing, blood transfusions and dialysis, if in the case of renal failure. The prevention of infections with Escherichia coli is achieved by personal hygiene, food hygiene and work hygiene.
Bacterial resistance to antibiotics is considered the most important health problem in developed and developing countries. Studies on new pharmaceutical strategies, such as probiotics and their derivatives, have increased. The purpose of this study is to isolate and purify bacteriocin and biosurfactant from Lactobacillus rhamnosus and investigate its antibacterial and anti-biofilm activity. Bacteriocin and biosurfactant produced by Lactobacillus rhamnosus standard strain were isolated and purified. Biosurfactant screening tests, including oil expansion test and drop spreading test, were conducted. Bacteriocin was separated using two different methods, including separation with the help of 2-propanol and separation with the help of ammonium sulfate. The purification of bacteriocin was realized by dialysis, and the effect of biosurfactant and bacteriocin on Staphylococcus aureus and Escherichia coli was realized using the disc diffusion method. The antibacterial properties of these substances were determined by diffusion method from its anti-biofilm disk with the help of the ELISA reader. Statistical Program for Social Sciences (SPSS) software was utilized for data analysis. The diameter of the non-growth halo of E.coli in contact with the disc impregnated with bacteriocin in concentrations of 250, 500, and 1000mg/ml was 21 ± 1, 21.33 ± 2.3 and 34.66 ± 7.02 mm, respectively, and in Staphylococcus aureus was evaluated as 18.33 ± 3.78, 24.33 ± 4.72 and 43.66 ± 4.72 mm, respectively. The order was evaluated as 18.33 ± 2.88, 25 ± 5, 43.33 ± 5.77 mm. The biofilm inhibition percentage was measured for Escherichia coli 0.36, 2.15, and 71.75%, respectively, and for Staphylococcus aureus 1.07%, 5.96%, and 53.3%, respectively, at the mentioned concentrations. The results showed that bacteriocin and biosurfactant isolated from Lactobacillus rhamnosus have high antibacterial and anti-biofilm properties
