Banu Kaskatepe

Rhamnolipid Biosurfactants Produced by Pseudomonas Species

Surfactants are chemical products widely used in our daily life in toothpaste and other personal hygiene and cosmetic products, and in several industries. Biosurfactants are surfactants of biological origin that can be produced by microorganisms and have many advantages, such as low toxicity and high biodegradability, compared to synthetic counterparts. Unfortunately, high production costs limit the use of biosurfactants. Low-cost production is the most important factor for biosurfactants to be able to compete in the global market place. This review presents general information on rhamnolipid biosurfactant produced by Pseudomonas species, as well as on their production and applications. In addition, industrial products and their wastes used for rhamnolipid production are reviewed in detail based on recent studies.

Biosurfactant production by Pseudomonas aeruginosain kefir and fish meal

The aim of this study was to increase rhamnolipid production by formulating media using kefir and fish meal for Pseudomonas aeruginosa strains isolated from different environmental resources. The strains, named as H1, SY1, and ST1, capable of rhamnolipid production were isolated from soil contaminated with wastes originating from olive and fish oil factories. Additionally, P. aeruginosa ATCC 9027 strain, which is known as rhamnolipid producer, was included in the study. Initially, rhamnolipid production by the strains was determined in Mineral Salt Medium (MSM) and then in media prepared by using kefir and fish meal. The obtained rhamnolipids were purified and quantified according to Dubois et al. (1956). The quantity of rhamnolipids of ATCC, H1 and SY1 strains in kefir media were determined as 11.7 g/L, 10.8 g/L and 3.2 g/L, respectively, and in fish meal media as 12.3 g/L, 9.3 g/L and 10.3 g/L, respectively. In addition, effect of UV light exposure on rhamnolipid production was also investigated but contrary a decrease was observed. The results indicate that P. aeruginosa strains isolated from various environmental resources used in this study can be important due to their rhamnolipid yield, and fish meal, which is obtained from waste of fish, can be an alternative source in low cost rhamnolipid production.

RS sample: Can be guide for empirical treatment of haematological malignancy patients?

Neutropenia due to intensive chemotherapy in haematological malignancy patients leaves the host vulnerable and makes them susceptible to infections. Infections are the most important cause of morbidity and mortality especially in haematological malignancy and chemotherapy patients. In addition, the use of multiple or inappropriate antibiotics leads to the development of resistant microorganisms. Therefore, the choice of empirical treatment is of vital important in these patient groups. Escherichia coli, Acinetobacter baumannii and Klebsiella pneumoniae are among the most frequently isolated Gram negative bacteria in neutropenic patients. Rectal swab (RS) samples were obtained from haematological malignancy patients not yet on chemotherapy or have no infection on chemotherapy period, E. coli was isolated from these samples, and A. baumannii and K. pneumoniae colonization were investigated. Susceptibilities of bacteria against antibiotics used in empirical treatment and prophylaxis were determined by using Gradient test strips according to the EUCAST recommendation. All isolates were sensitive against colistin. The resistant rates of antibiotics were detected as 39.1%, 9.4%, 6.8%, 35.1%, 31%, 39.1% for ciprofloxacin, meropenem, imipenem, piperacillin-tazobactam, cefepime, ceftazidime respectively The clonal relationship between Gram negative bacteria of intestinal flora and infection agents of same patient was investigated by Pulsed-Field gel electrophoresis. Twenty-three of the 30 patients (76.6%) were found to have a clonal relationship between the bacterial isolates before and after infection. It was determined that it can be able to predict with RS samples about possible agents of infection and their antibiotic susceptibility patterns.

Chemical composition and antimicrobial activity of the commercial Origanum onites L. oil against nosocomial carbapenem resistant extended spectrum beta lactamase producer Escherichia coli isolates

In recent years rapidly growing antibiotic resistance has increased interest toward natural products, especially essential oils because of their various effects. The aim of this study was to identify the chemical composition of the commercial Origanum onites essential oil (EO) and to investigate the antimicrobial activity by disc diffusion and dilution methods, against ten different ATCC strains, including eight bacteria, two yeasts and seventy-nine clinical nosocomial Escherichia coli isolates that produce extended spectrum beta lactamase (ESBL). The chemical composition of EO was analyzed by GC and GC-MS. The major compounds of the EO were determined as carvacrol (51.4%) followed by linalool (11.2%), p-cymene (8.9%) and γ-terpinene (6.7%). O. onites EO had antimicrobial activity against all standard strains and inhibited microbial growth of ESBL positive E. coli isolates. According to our results, O. onites EO may be an alternative to synthetic drug, used in combination with other antibiotics for treatment of infection caused by multidrug resistant bacteria after testing toxic effects and irritation at preferred doses on human.