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In this research, Pseudomonas strains were isolated from clinical specimens sputum, stool, urine and burns and their alginate production were evaluated under various conditions.
The effect of osmotic pressure in alginate production as one of the environmental growth conditions was investigated. Isolation and assay of alginate is necessary for study of osmotic pressure effect. Assay for alginate was performed by carbazole method with borate. D–glucoronic acid and alginic acid were used as standard. Several culture media used are as follows: MacConkey agar containing; 0.25 and 0.5 M NaC1, glycerol (1-3%, 5% and 10%) and nutrient agar containing 1% glucose used to increase the osmotic pressure. Specimens were incubated in 10 tubes containing 10 ml of the above media at 25° C for 7 days. Alginate was extracted after centrifugation, precipitation with ethanol and dealcoholization and then dried in vacuum drier. Maximum alginate production were obtained in MacConkey agar containing 2% glycerol, indicating the medium more suitable for alginate production The highest amount of alginate was isolated from sputum of a chronic bronchitis patient. This strain (strain 7101) produced 5212 mg/l alginate on MacConkey agar containing 2% glycerol and 607 mg/l on non glycerol medium. The lowest amount of alginate on glycerol medium related to a burn’s specimen with 140mg/l.
These results indicated the role of glycerol in increasing of osmolarity and alginate production. Thus, alginate production relates to the kind of strain and clinical sources (eg, lungs), as well growth conditions.