A strain of Aspergillus niger PR-142 native to northern coast of Peru was subjected to successive processes of mutagenesis by ultraviolet light (UV) irradiation at 253.7 nm to increase the production of fructooligosaccharides (FOS). An initial selection was made by considering the mutants with increased invertase activity followed by the measurement of β-fructosyltransferase (FTase) activity both in mycelium and extracellular environment. Five selected mutants, which showed increased values of mycelium invertase activity (ranging from 101 to 128% as compared to the parent strain) at 40°C and sodium dodecylsulfate 0.15 (w/v), were grown in a fermentative medium in 50 mL conical tubes on a rotary shaker, and their FTase activity was determined. The 6-M69 mutant showed the most active mycelium activity of 1.5 fold as compared to the parent strain. When the same reaction was performed betw...

In order to obtain a native isolate with high β-fructofuranosidase activity (FFase), a preliminary selection of 44 isolates, predominantly formed by Aspergillus niger (72%), was performed among 167 isolates of Aspergillus native to the Peruvian coast (Casa grande, Cartavio, Paramonga and Tacama). In addition, genetic diversity was studied using molecular markers, Inter Simple Sequence Repeats (ISSR). The FFase activity of these 44 isolates was compared and the isolate which showed the highest fructosyltransferase (FTase) activity was identified molecularly at the species level by DNA sequencing. Cluster analysis indicated 16 sub-genetic groups of which 11 of them were morphologically identified as Aspergillus niger. Samples from Paramonga showed the highest genetic diversity as explained by the Shannon diversity index (I= 0.21). No positive association was found between the genetic dive...