Stress tolerance and growth of trehalose and mannitol deficient mutants in Aspergillus niger

There are several fungal species including Aspergillus niger that are responsible for food spoilage. The conidia of Aspergillus niger contain mannitol and trehalose and these compounds act as stress protectants and keep the cells viable. In my experiments, I observed the survival after stress in trehalose and mannitol deficient mutants of Aspergillus niger and compared with wild type strains. I applied different treatments like heat shock, freeze-drying and different energy sources on mutants and wild types spores at different ages. The results indicate that 1-month-old spores of mutant of ΔtppB and ΔmpdA are more vulnerable at high and low temperatures. These experiments indicate that the trehalose deficient mutant ΔtppB and the mannitol deficient mutant ΔmpdA are more sensitive compared to wild type and most probably due to their lower mannitol and trehalose levels