جستجوی مقالات مرتبط با کلیدواژه "xanthan" در نشریات گروه "زیست شناسی"

Today, the use of natural materials in wound dressing has attracted more attention that can overcome the serious environmental problems caused by conventional synthetic materials. In this study, first gelatin was extracted from Caspian kilka fish waste and then used to make composite films in pure form (G), in combination with xanthan (GX) and Anghouzeh oil (GXA). Mechanical properties, swelling index and surface morphology of the films were investigated. The antibacterial and anti-biofilm effects of G, GX and GXA films were also evaluated. The highest tensile strength was recorded for GX film (37.30±0.59MPa) and the lowest value was recorded for pure gelatin film (11.74±0.2MPa). For elongation at break, the highest value was measured in GXA film (54.87±0.21%) and the lowest was in G film (15.61±0.68%). The highest swelling index was recorded for GX film at 300±15.3%. GXA film presented the highest antimicrobial and anti-biofilm activities. The results of these study showed that the film made of gelatin in combination with xanthan and Anghouzeh oil has ideal mechanical and antibacterial properties to use in wound dressing structure.

Xanthan is a heteropolysaccharide that is produced by the group of plant pathogen bacteria from Xanthomonas genus. Usually، the media containing glucose، sucrose and starch is used for xanthan production. Because their preparation and transferring is expensive، the final cost of xanthan production by these carbon sources is high. On the other hand، many Xanthomonas species such as X. campestris are not able to use cheap media rich of lactose such as whey to produce xanthan due to the low expression and sometimes the defect of their β-galactosidase enzyme. The access to bacterial strains capable of decomposing lactose will provide a possibility for producing a valuable commercial product (xanthan) from an inexpensive carbon source (whey). In the present study، a collection containing 210 isolated Xanthomonas citri subsp. citri Iranian strains from citrus orchards in south Iran was studied. Then، the genus of these bacteria was determined by using molecular techniques and sequencing of 16S-rDNA gene. Also، their growth in lactose – based medium was investigated. Among 210 strains، 27 strains were able to grow on lactose rich medium. Then، the genus of these bacteria was proved by sequencing of 16S-rDNA gene and comparison with another 16S-rDNA gene sequences existing in NCBI. Also، these bacteria had considerable growth in lactose-based medium. Discussion and At last، we can say that separated lactose-positive Xanthomonas strains from southern citrus orchards have good ability to utilize lactose and in the near future، it would be possible to apply these native strains for xanthan production in cheaper lactose media such as whey.

Xanthan, the extracellular polysaccharide of the phytopathogenic bacterium Xanthomonas campestris, has many applications in different industries, especially in petroleum, food and pharmaceutical industries. Development of the simple and inexpensive methods for accurate measurement of xanthan concentration in aqueous solutions would be greatly appreciated. In this work, quantitative effect of xanthan interaction with congo-red was spectrophotometrically evaluated. It was demonstrate that at low concentrations, xanthan, induces hypochromocity (decreasing of the maximum absorbance) in solutions of congo red dye. Also, an overnight conservation of xanthan solutions before performing the colorimetric test is recommended for its establishment; simple up/down agitation provides an appropriate and quick procedure to obtain a mixture of the colored liquid and the xanthan solution. The best results were obtained by using Congo red dye at 4080- μg/l concentrations, 492 nm wavelength at all of the tested xanthan concentrations. Heating of xanthan solutions at 121 °C affected the absorbance without remarkable change in pattern of absorbance. This research provides basic information for development of a colorimetric method for measurement of xanthan concentration in aqueous solutions.