Extracellular polymer substance synthesized by a halophilic bacterium Chromohalobacter canadensis 28

Halophilic microorganisms are producers of a lot of new compounds whose properties suggest promising perspectives for their biotechnological exploration. Moderate halophilic bacterium Chromohalobacter canadensis 28 was isolated from Pomorie salterns as an extracellular polymer substance (EP) producer. The best carbon source for extracellular polymer production was found to be lactose, a sugar received as a by-product from the dairy industry. After optimization of the culture medium and physicochemical conditions for cultivation, polymer biosynthesis increased more than 2-fold. The highest level of extracellular polymer synthesis by C. canadensis 28 was observed in an unusually high NaCl concentration (15% w/v). Chemical analysis of the purified polymer revealed the presence of an exopolysaccharide (EPS) fraction (14.3% w/w) and protein fraction (72% w/w). HPLC analysis of the protein fraction showed the main presence of polyglutamic acid (PGA) (75.7% w/w). EPS fraction analysis revealed the following sugar composition (% w/w): glucosamine 36.7, glucose 32.3, rhamnose 25.4, xylose 1.7, and not identified sugar 3.9. The hydrogel formed by PGA and EPS fractions showed high swelling behavior, very good emulsifying and stabilizing properties, and good foaming ability. This is the first report for halophilic bacterium able to synthesize a polymer containing PGA fraction. The synthesized biopolymer shows an extremely high hydrophilicity, due to the simultaneous presence of PGA and EPS. The analysis of its functional properties and the presence of glucosamine in the highest proportion in EPS fraction clearly determine the potential of EP synthesized by C. canadensis 28 for application in the cosmetics industry

Variasjoner i synsfeltmålinger hos unge, friske mennesker

Målsetting: En kohortstudie med formål å undersøke variabiliteten av netthinnens lysdiskrimineringsevne med Medmont M700 kuleperimeter hos unge, friske mennesker i en målesesjon før og etter to uker. Sekundært ble variabiliteten i synsfeltresultater for erfarne og uerfarne testpersoner sammenlignet. Metode: Synsfeltmålinger ble utført på begge testgruppene over en periode på to uker. Studien ble delt inn i to målesesjoner som hver inneholdt tre gjentatte fullterskelsynsfeltmålinger. Resultatene ble anonymisert og analysert. Variabiliteten ble målt i form av gjennomsnittsstandardavvik for begge testgruppene. Resultater: Uerfarne testpersoner hadde mindre variasjoner i målesesjon 2 enn i målsesjon 1. Erfarne testpersoner hadde større variasjoner i målesesjon 2 enn i målesesjon 1. Uerfarne testpersoner viste en læringseffekt, noe de erfarne testpersonene ikke gjorde. Variasjonene var generelt størst perifert og minst midtperifert. Konklusjon: Små forskjeller mellom erfarne og uerfarne testpersoner, mellom målesesjon 1 og 2 og mellom høyre og venstre øye og høy individuell forskjell i gruppene

Extracellular polymer substance synthesized by a halophilic bacterium Chromohalobacter canadensis 28

Halophilic microorganisms are producers of a lot of new compounds whose properties suggest promising perspectives for their biotechnological exploration. Moderate halophilic bacterium Chromohalobacter canadensis 28 was isolated from Pomorie salterns as an extracellular polymer substance (EP) producer. The best carbon source for extracellular polymer production was found to be lactose, a sugar received as a by-product from the dairy industry. After optimization of the culture medium and physicochemical conditions for cultivation, polymer biosynthesis increased more than 2-fold. The highest level of extracellular polymer synthesis by C. canadensis 28 was observed in an unusually high NaCl concentration (15% w/v). Chemical analysis of the purified polymer revealed the presence of an exopolysaccharide (EPS) fraction (14.3% w/w) and protein fraction (72% w/w). HPLC analysis of the protein fraction showed the main presence of polyglutamic acid (PGA) (75.7% w/w). EPS fraction analysis revealed the following sugar composition (% w/w): glucosamine 36.7, glucose 32.3, rhamnose 25.4, xylose 1.7, and not identified sugar 3.9. The hydrogel formed by PGA and EPS fractions showed high swelling behavior, very good emulsifying and stabilizing properties, and good foaming ability. This is the first report for halophilic bacterium able to synthesize a polymer containing PGA fraction. The synthesized biopolymer shows an extremely high hydrophilicity, due to the simultaneous presence of PGA and EPS. The analysis of its functional properties and the presence of glucosamine in the highest proportion in EPS fraction clearly determine the potential of EP synthesized by C. canadensis 28 for application in the cosmetics industry