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Biodiversity and phytase capacity of yeasts isolated from Tanzanian togwa

Andreas Hellström (Institutionen för kemi- och bioteknik, Livsmedelsvetenskap) ; Ricardo Vázques-Juárez ; Ulf Svanberg (Institutionen för kemi- och bioteknik, Livsmedelsvetenskap) ; Thomas Andlid (Institutionen för kemi- och bioteknik, Livsmedelsvetenskap)
International Journal of Food Microbiology (0168-1605). Vol. 136 (2010), 3, p. 352-358.
[Artikel, refereegranskad vetenskaplig]

The focus of the present investigation was on the Tanzanian fermented food togwa as a source for dietary iron and zinc, and the potential for mineral availability improvements using selected yeasts. To establish the content of target minerals and main inhibitor for intestinal uptake, iron and zinc as well as the mineral chelating phytic acid, (IP6 or phytate) were determined in naturally fermented togwa. Yeasts were isolated from sorghum, maize and cassava based togwa, and identified by sequencing the D1/D2 region of the LSU rRNA gene. The isolated yeasts were subsequently screened for phytase activity. The total iron content in sorghum, maize and cassava based togwa were 41.5 (±7.2), 85.4 (±31.9) and 28.6 (±3.8) μg/g dw (dry weight) respectively. The zinc content was 12.3 (±3.1), 11.0 (±1.1) and 6.4 (±4.5) μg/g dw in sorghum, maize and cassava based togwa, and the phytate content in the three varieties were 2.6±1.2, 4.7±0.8 and 0.4±0.4 μmol/g dw respectively. The phytate levels in the sorghum and maize based togwa are expected to substantially reduce the availability of iron. The molar ratio phytate to iron for these two varieties were estimated to be 3.5:1 and 3.1:1 respectively. In general, a phytate to iron molar ratio below 1 is needed to increase the availability of iron. Among 26 isolates, 9 different species could be distinguished: Issatchenkia orientalis, Pichia anomala, Pichia norvegensis, Pichia burtonii, Pichia guilliermondii, Kluyveromyces marxianus, Saccharomyces cerevisiae, Hanseniaspora guilliermondii and Candida glabrata. The strains were screened for phytase activity in YPD supplemented with 0.5 mM IP6. Of 26 screened strains, the phytase activity was most prominent in strains of I. orientalis and H. guilliermondii. The strains and data constitute a basis for further improvements of iron and zinc bioavailability in togwa.

Nyckelord: Mineral availability, Togwa, Cereals, Yeast phytase, Fermentation

Denna post skapades 2009-12-16. Senast ändrad 2015-07-01.
CPL Pubid: 103821


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Institutionen för kemi- och bioteknik, Livsmedelsvetenskap (2005-2014)



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Yeast biotechnology for nutritional improvements of fermented cereal-based foods - Phytate degradation and folate production