Optimization of kappa-carrageenase production by Pseudoalteromonas sp. AJ5.
OBJECTIVE
To optimize the culture conditions of Pseudoalteromonas sp. AJ5 for a higher production of extracellular kappa-carrageenase.


METHODS
A kappa-carrageenan-degrading bacterium AJ5, capable of utilizing kappa-carrageenan as sole source of carbon and energy, was isolated from the intestine of holothurian Apostichopus japonicus by enrichment culture technique. The strain was identified as the genus Pseudoalteromonas sp. according to its morphological and physiological characterization and 16S rRNA gene analysis. Culture conditions for the bacterium were standardized for the maximal productivity of the extracellular kappa-carrageenase by the single factor and orthogonal tests.


RESULTS
According to the single factor test, the optimal culture conditions were: 75 mL medium in 250 mL Erlenmeyer flask, shaking speed of 150 r/min, inoculum's volume 7%, and pH 8.0. Based on the single factor and orthogonal tests the optimal medium components were: kappa-carrageenan (1 g/L), beef extract (2 g/L ), NaCl (20 g/L), K2HPO4.3H2O (1 g/L), MgSO4.7H2O (0.5 g/L), MnCl2.4H2O (0.2 g/L), FePO4.4H2O (0.01 g/L), with the incubation temperature and time of 28 degrees C and 28 h.


CONCLUSIONS
Pseudoalteromonas sp. AJ5 secreted an extracellular kappa-carrageenase. Under the optimal culture conditions, four-fold increase in kappa-carrageenase activity was achieved as compared to the control.
Ma
Yuexin
Y
Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China. mayuexin@dlfu.edu.cn
Dong
Shuanglin
S
Liu
Shuanglian
S
Mou
Haijin
H
Jiang
Xiaolu
X
D002244:Carbon / Q000737:chemistry / Q000494:pharmacology; D018929:Cell Culture Techniques / Q000379:methods*; D049109:Cell Proliferation / Q000187:drug effects; D003470:Culture Media / Q000494:pharmacology; D004275:DNA, Ribosomal / Q000235:genetics; D006026:Glycoside Hydrolases / Q000096:biosynthesis* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D009584:Nitrogen / Q000737:chemistry / Q000494:pharmacology; D010802:Phylogeny; D031161:Pseudoalteromonas / Q000166:cytology / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D012492:Salts / Q000494:pharmacology; D013997:Time Factors
D003470:Culture Media; D004275:DNA, Ribosomal; D012492:Salts; D002244:Carbon; D006026:Glycoside Hydrolases; D009584:Nitrogen