ABSTRACT

Microorganisms associated with Deteriorated dioscorea rotundota L. (white yarn) was studied. Discorea rotundata (white yam) with no symptoms of infection were procured locally from different yam sellers in Umuahia main market, Ubani, Abia state. The yam samples were stored using different methods which include; Ambient temperature, Polyethylene bag at 40°C, Unprotected from rain, Unprotected from rodent attack (27°C), dark cupboard (3 0°C) and Ambient temperature at 27°C and were labeled samples A, B, C, D and E respectively. The yam samples were stored for four (4) weeks in which the spoilage progress was monitored after which bacteria and fungi were isolated and identified using standard methods of analysis. A total of 9 isolates (four bacteria and 5 fungi) were isolated after some physiological, morphological and biochemical test were carried out. The study revealed that the yam sample stored at ambient temperature (2 7°C) (sample E) showed no sign of spoilage up to day 18 while rodent attack, dark cupboard and rain all facilitates spoilage of white yarn. The bacteria isolated were Erwinia sp., Pseudomonas specie, Staphylococcus specie and E. coIL The fungi isolated were Aspergillus niger, Aspergillus flavus, Rhizopus stolonfer, Fusarium oxysporium and Mucor spp. The incidence of occurrence of these organisms revealed that Aspergillus niger had the highest occurrence (31.25%) for fungi and occurred more in sample stored with polyethylene bag while Mucor spp had the least occurrence (12.5%). Erwinia sp and E. co/i had the highest occurrence (29.4 1%) for bacteria and was found in the sample stored with polyethylene and ambient temperature. While Staphylococcus specie had the lowest occurrence (I 765%). The research has isolated and identified the microorganisms associated with the spoilage of white yam.