Naslov
Enhancement of Betanin Yield in Transformed Cells of Sugar Beet (Beta vulgaris L.)

Autori
Križnik, Bojana ; Pavoković, Dubravko

Izvornik
Acta botanica Croatica (0365-0588) 69 (2010), 2; 173-182

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
elicitors; in vitro tissue culture; pigments; secondary metabolites

Sažetak
Betanin belongs to a large family of betacyanin pigments, betalains, and in food industry it is established as a powerful antioxidant and natural colorant. The main source of betanin is a red beet (Beta vulgaris L.), whose yield depends on abiotic and biotic factors in the field. Sugar beet cells, transformed by a wild strain B6S3 of Agrobacterium tumefaciens, strongly produce betanin and could be its alternative and stable production source. With the aim to enhance its yield, cell suspensions were initiated from friable calli. Biomass accumulation, betanin content and yield were monitored during 21 days in relation to changes of sucrose concentration, modifications of minerals in nutrient medium, and the usage of elicitors. Results showed that elevating sucrose levels from 3 to 4%, 5%, or 6% (w/v) in the original medium strongly induced biomass accumulation followed by an increase in betanin yield up to 250%. Modification of minerals in the medium additionally increased betanin yield up to 20% on few instances: 40 mg/L was recorded at day 10 with 5% and 6% of sucrose. The highest yield at 53 mg/L was reached at day 21 on 4% Suc in the modified medium. High sucrose concentrations positively affected betanin accumulation only during lag phase of the cell suspension, but afterwards the trend reversed. Calcium and yeast extract were used as abiotic and biotic elicitor, respectively, in early exponential phase of subculture (day 7). Calcium ions (at 10 fold higher concentration than in the control) failed to increase betanin yield as well as yeast extract at 0.25% (w/v). Yeast extract at 1.25% provoked excretion of betanin at day 4, and cell necrosis at day 7 after elicitation. Taken together, in our system, sucrose affected betanin yield more strongly than medium modifications or elicitors. Yeast extract could be used for reverse-sequestration of betanin where the cells can be used over an extended period.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

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