Abstract

The bioflocculant producing microorganisms can be isolated from different sources, most especially sources
where natural flocculation occurs. This study isolated bioflocculant producing fungi from water sediment of
Bosso dam and grew them on waste orange juice as fermentation substrate to produce bioflocculant. The watersediment
samples were serially diluted and cultured on Sabaroud Dextrose Agar (SDA). Distinct colonies were
sub-cultured on fresh SDA plates and identified by comparing their morphological and cultural characteristics
with those of known taxa using a mycological atlas. The isolates were further screened for bioflocculant
production by growing them on waste orange juice and using the resulting cultured supernatant to check for
flocculation efficiency on Kaolin clay suspension. Three fungi namely Aspergillus niger, Aspergillus fumigatus
and Trichophyton megninii were isolated. All the fungi demonstrated bioflocculant production but the cultured
supernatant of T. megninii recorded the highest flocculation efficiency of 74.6% followed by A. niger (68.3%)
and then A. fumigatus (63.5%). The optimum bioflocculant production by T. megninii was recorded at pH 7
(86.5%), temperature of 25°C (61.7%), and incubation of 86 h (75.8%). The three isolates and waste orange
juice can respectively be used as fermentation organisms and substrate for bioflocculant production especially
when the culture conditions are well optimized.

Key words: Bioflocculant, waste orange, Bosso Dam, fungi