The genome of a fungal strain <italic>Penicillium chrysogenum</italic> strain HKF42, which can grow on 20% sucrose has been annotated for 7595 protein coding sequences. On mining of CAZymes, we could annotate a β-fructofuranosidase gene responsible for fructo-oligosaccharides (FOS) synthesis which is a known prebiotic. The enzyme activity was demonstrated and validated with the generation of FOS as kestose and nystose.