In contrast, Younes, Sellimi, Rinaudo, Jellouli and Nasri observed an inverse correlation between fungal growth and chitosan MW for Fusarium oxysporum, but no MW correlation for Aspergillus niger. Kulikov et al. concluded that molecular heterogeneity is the primary reason for discrepancies in reported correlations between biocidal activity and physicochemical characteristics of different types of chitosan/COS.