EFFECT OF HEAT TREATMENT ON MYCELIA GROWTH AND SPORE GERMINATION OF Aspergillus niger OBTAINED FROM DECAYED CUCUMBER FRUITS (Cucumis sativus)

Abstract

This work investigated effect of heat treatment on mycelia growth and spore germination of Aspergillus niger obtained from decayed cucumber fruits. Both mycelia disc and sample aliquots of the spore suspensions of Aspergillus niger were separately treated with hot air (HA) and hot water (HW) at the following heat regimes: 40°C and 50°C for 10, 20 and 30 minutes each while non-heated mycelia and spores served as control. Results showed that the mycelia growths of A. niger following each HA treatment increased in this order: 50°C – 10 minutes > 50°C – 20 minutes > 50°C – 30 minutes > 40°C – 10 minutes > 40°C – 20 minutes / 40°C – 30 minutes and 40°C – 20 minutes > 40°C -10 minutes > 50°C – 20 minutes > 50°C – 10 minutes > 50°C – 30 minutes > 40°C – 30 minutes following each HW treatment. Similarly, germinating spores of A. niger following each HA treatment increased in this order: 40°C - 10 minutes > 50°C for 20 minutes > 40°C – 30 minutes > 40°C - 20 minutes > 50°C - 30 minutes > 50°C - 10 minutes and 40°C - 30 minutes > 50°C - 20 minutes > 40°C – 10 minutes > 40°C - 20 minutes > 50°C - 30 minutes > 50°C - 10 minutes after each HW treatment. Thus, this probably implied that HA treatment at 40°C – 10 minutes, 50°C – 10 and 20 minutes and HW treatment at 40°C – 20 minutes, 40°C – 30 minutes could be effective in delaying the development of Aspergillus niger in cucumber fruits.