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Enhancing the Production of Reducing Sugars from Cassava Peels by Pretreatment Methods
(International Journal of Science and Technology, 2012) Olanbiwoninu, Afolake Atinuke; Odunfa, Sunday Ayodele
Cassava peel is one of the major biomass wastes in Nigeria obtained from production of cassava tuber for human consumption, starch production and industrial uses. The objective of this work was to investigate the optimal condition for pretreating cassava peel with dilute sulphuric acid, methanol with catalyst (organosolv) and alkali prior to microbial enzymatic hydrolysis for the production of fermentable sugars. The pretreated samples reducing sugar yield was measured after enzymatic hydrolysis. The result shows that acid hydrolysis using sulphuric acid at a concentration of 0.1M at 120oC for 30 min gave a maximum reducing sugar yield of 88.8% and 98%, followed closely by methanol treated peels (78 and 98% ) while alkali pretreated peels produce the least (66 and 88%) for Pseudomonas flourescens and Aspergillus terreus respectively. In this study, H2SO4 and methanolysis treated peels prior to enzymatic hydrolysis had a greater capacity for hydrolyzing cassava peels than NaOH and also combination of pretreatments method with enzymatic treatment is an alternative to improve efficiency of reducing sugar production from cassava peel.
Production of Fermentable Sugars from Organosolv Pretreated Cassava Peels
(Advances in Microbiology, 2015) Olanbiwoninu, Afolake Atinuke; Odunfa, Sunday Ayodele
Cassava peels are rich in lignocellulolytic materials which are not readily amenable to enzymatic hydrolysis; hence, there is a need for a suitable pretreatment method that will support enzymatic hydrolysis. This study was designed to investigate lignocellulolytic organisms that would effectively support the bioconversion of organosolv pretreated cassava peels to fermentable sugars. Decaying cassava peels were collected into sterile bottles and microorganisms isolated, characterized and screened for lignocellulolytic enzymes production. Optimum temperature, pH and nutrient sources for enzyme production were determined. Organosolv pretreatment was carried out using methanol with varied concentration of catalyst (0.01 - 3 M), reaction time (15 - 60 min) and substrate size. Crude enzymes (cellulase and xylanase) from the isolates were added to the pretreated peels and bioconversion was monitored by measuring the concentration of reducing sugar and calculating the percentage peel hydrolysis. The fermentable sugars produced were quantified using gas chromatography. Pseudomonas fluorescens and Aspergillus terreus were isolated. P. fluorescens produces 2.8 u/mL of crude enzymes optimally at 50°C and pH 8 while A. terreus produces 3.4 u/mL optimally at 40°C, pH 6. Both isolates utilizes CarboxyMethylCellulose (CMC) and yeast extract as their best carbon and nitrogen sources. Highest percentage of peel hydrolysis was 67% for P. fluorescens at 0.01 M and 0.05 M for A. terreus (94%). Highest concentration of fermentable sugar was produced by A. terreus crude enzyme (331.79 mg/L glucose, 45.3 mg/L rhamnose and 46.52 mg/L xylose). P. fluorescens and A. terreus effectively supported the bioconversion of organosolv pretreated cassava peels to fermentable sugars.
Production of Cellulase and Xylanase by Aspergillus terreus KJ829487 Using Cassava Peels as Subtrates
(2016) Olanbiwoninu, Afolake Atinuke; Odunfa, Sunday Ayodele
Cassava (Manihot esculenta, Crantz) is one of the most important food plants in West Africa. Its peels are made up of cellulose, hemicellulose and lignin. This lignocellulolytic biomass can be converted using microbial enzymes to fermentable sugars which have wide range of biotechnological relevance in many fermentation processes. The aim of this study is to screen filamentous fungi from decaying cassava peels that are good producers of xylanases and cellulases. Decaying parts of cassava peels were obtained and brought to the laboratory for further work. Fungi were isolated, identified and screened for cellulase and xylanase production. Isolate with highest frequency of occurrence and enzyme production was identified using phenotypic and molecular method. Optimisation of growth conditions for enzymes production was monitored using the DNSA method, also saccharification of cassava peel were carried out using the enzymes obtained from the isolate. Aspergillus terreus KJ829487 was the predominant fungus. It produces cellulases and xylanases optimally at 40°C, pH 6 and 8, utilising carboxymethylcellulose (CMC) or xylose and yeast extracts as its carbon and nitrogen sources respectively. Saccharification of the peels yielded 584 mg/L glucose, 78 mg/L xylose and 66 mg/L rhamnose. Aspergillus terreus KJ829487 obtained from cassava peels have the ability to produce high concentration cellulases and xylanases which effectively hydrolysed the lignocelluloses’ biomass to fermentable sugars.
Riboflavin enriched iru: A fermented vegetable protein
(2017) Olanbiwoninu, Afolake Atinuke; Irokosu, Olaoluwa; Odunfa, Sunday Ayodele
African locust bean (Parkia biglobosa) cotyledon is fermented in most countries of West Africa to produce a soup condiment, known as ‘iru’ in Yoruba language, or ‘dawadawa’ in the predominant Hausa language. Iru is rich in minerals and serves as a source of protein supplement in the diet of poor families. Riboflavin (Vitamin B2) is an essential component of basic cellular metabolism but its daily requirement is not met in Nigeria particularly among the rural dwellers. Therefore, the provision of a riboflavin enriched iru will help to eradicate problems encountered from riboflavin deficient diet. Iru was purchased from three different markets in Ibadan, Oyo State, Nigeria. From the iru, microorganisms were isolated, characterised, screened for riboflavin production and co-cultured for the production of riboflavin enriched iru. Sixty-three bacteria were isolated and identified as Micrococcus varians (9), Staphylococcus species (27), Bacillus species (24) and Micrococcus luteus (3). Bacillus subtilis IR50 produced highest riboflavin 25.77 mg/L, followed by Staphylococcus spp. strain IR26 23.37 mg/L, while M. varians IR49 had the least riboflavin production 6.35 mg/L. Mixed culture of B. subtilis IR50 and Bacillus licheniformis IR28 produced the highest riboflavin of 4.5 mg/L, Staphylococcus aureus IR06 and B. subtilis IR50 produced 2.3 mg/L, while B. subtilis IR50 produced 1.5 mg/L when used singly. The result shows that B. subtilis IR50 have the potential to increase the riboflavin content of iru and therefore will contribute to bioenrichment technology.
Microbial interaction in selected fermented vegetable condiments in Nigeria
(International Food Research Journal, 2018) Olanbiwoninu, Afolake Atinuke; Odunfa, S A
Fermented condiments remain the key constituents of diets throughout the world especially in Africa and Asia. The process of fermentation of these condiments involves different types of microorganisms which interact with each other and mode of interaction need to be understood. Iru and ogiri-egusi were purchased from retail markets in Oyo State, Southwest Nigeria. Microorganisms were isolated, characterised and co – cultured for fermentation of the condiments. Bacteria obtained were 168; 100 Gram-positive bacteria, 30 Gram-negative and 38 Lactic acid bacteria. Bacillus species comprising B. subtilis, B. pumilus, B. licheniformis and B. megaterium had the highest frequency of occurrence of 72% while Staphylococcus epidermidis and some lactic acid bacteria were consistently present. B. subtilis had the highest growth rate at 60 h when used singly both in iru and ogiri-egusi. Co – culturing B. subtilis and S. epidermidis in iru and ogiri-egusi showed an increase in growth rate of 46 and 23% respectively while addition of L. plantarum gave a decrease of 33% in growth thus depressing the growth of B. subtilis. The factors at play by the lactic acid bacteria during the interaction were presumed to be due to production of acids and metabolites which have effect on the proteolytic Bacillus species. Knowledge of the key roles of the organisms studied facilitates the development of starter cultures using mixed cultures.