Molecular identification and technological properties of yeasts isolated from spontaneously fermented cassava waste pulp

Adelodun L Kolapo,Raoofat O Salami,Gbemisola O Onipede

doi:10.36547/nbc.898

Adelodun L Kolapo, Raoofat O Salami + Show 1 more

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https://doi.org/10.36547/nbc.898

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Abstract

The aim of this work was to report on molecular identification and technological properties of the yeast flora isolated from spontaneously fermented cassava waste pulp. This was done with a view of obtaining yeast strains that could be used as a starter culture for the fermentation of cassava waste pulp. Molecular identification was based on the nucleotide sequence of the ITS region of the genomic DNA of the yeast isolates while the technological properties evaluated include linamarase (U/mL), gelatinase, and haemolytic activity; growth at pH 2.5 and tolerance to 2 % bile salt. All the representative five isolated yeasts were identified as Geotrichum silvicola KLP04 – KLP08. The isolates exhibited linamarase activity ranging between 3.3 and 4.2 with strain KLP04 having the highest value and strain KLP05 the least. None of the isolates demonstrated gelatinase and haemolytic activity except strain KLP08 which was partially haemolytic. All the examined yeasts exhibited good growth at pH 2.5, with strain KLP08 having the highest viable counts of 4.1 log10cfu/ml and strain KLP04 the least value of 3.5 log10cfu/ml after 72 h of growth. All the identified yeasts showed strain-specific tolerance to 2% bile salt with strain KLP04 having the highest viable count of 4.3 log10cfu/ml and strain KLP08 the least value of 2.2 log10cfu/ml at the end of 72 h of incubation. Based on all the examined technological properties, Candida silvicola KLP04 strain had the highest potential to be considered for starter culture for the fermentation of cassava waste pulp.

Highlights

The maize grain is a major feed grain and a standard component of livestock diets where it serves as a source of energy (Heuzé et al 2017)
In contrast to Latin America and Southeast Asia, where the majority of cassava is exported for industrial purposes or animal feed; about 70 to 80 % of cassava produced in Nigeria is utilized for human consumption (Dada et al 2010) and only a reported 5 % of cassava was used as livestock feed (Apata and Babalola 2012)
The four isolates from this study were identified as Geotrichum silvicola while the fifth isolate was identified as Geotrichum candidum

Summary

Introduction

The maize grain is a major feed grain and a standard component of livestock diets where it serves as a source of energy (Heuzé et al 2017). The attendant effect of this scenario on the increased cost of animal feeds has been an age-long one for which cheaper alternative feedstuffs have been developed to replace the expensive conventional ones (Salami and Odunsi 2003) Due to their cheapness, agricultural wastes and by-products of food processing have become the first line of choice as unconventional feed materials in livestock. In recent times, the industrial potential of cassava to produce starches for textiles, pharmaceutical, food, alcohol, acetone, and dextrin industries are largely being exploited This current trend is adding another stream of cassava waste to those that have been known to be generated from the processing of cassava tuber for human food. Fermentation of cassava products and by-product with starter microorganisms such as Saccharomyces cerevisiae and Lactobacillus spp

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