Protein Enrichment of Irish Potatoes by Fermentation Process Using Mutant Isolates of Latobacillus Bulgaricus

Abstract

The study undertook the mutational selection of lactic acid bacteria used for the fermentation of peeled Solanum tuberosum (Irish Potatoes, Subtrate) in order to isolate mutants that may produce fermented Irish potatoes product with improved nutritional quality (i.e increase protein content). Lactic acid bacteria were isolated from local yoghurt (“kindirmo” in hausa language) that were morphologically and culturally characterised and found to be predominantly Lactobacillus bulgaricus. Four (4) mutants selected randomly from Lactobacillus bulgaricus subjected to UV-light irradiation at 20 secs , 25 secs, 30 secs and 35 secs periods of exposure. The mutants exhibited similar morphological and cultural characteristics as the wild type strain. Fermentation of peeled Irish potatoes with wild type Lactobacillus bulgaricus gave no significant increase (P>0.05) in crude protein content from 7.37±0.42 g/100 g on the zero day to 8.73±0.43 g/100 g on the 5th day of fermentation, whereas, the mutant isolates gave a significant increase (P<0.05) of crude protein content from 7.37±0.42 g /100 g (zero day of fermentation) to 11.52±0.62 g/100 g, 12.18±0.62 g/100 g, 9.72±0.88 g/100 g and 14.50±0.52 g/100 g at 6th day of fermentation respectively. The mutant isolates, Lb35, showed the highest crude protein content (16.91±0.73 g/100 g) increase after the 5th day of fermentation of Irish Potatoes (Solanum tuberosum). The genetic analysis revealed that the Lactobacillus bulgaricus studied did not harbour any extrachromsomal element.