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  • Catalytic and physical feat...
    Fraga, Jully Lacerda; da Penha, Adrian Chaves Beserra; Akil, Emília; Silva, Kelly Alencar; Amaral, Priscilla Filomena Fonseca

    3 Biotech, 10/2020, Letnik: 10, Številka: 10
    Journal Article

    Lipase activity (337 U/g dry weight of cell debris) was detected in cell debris after ultrasound treatment of Yarrowia lipolytica cells cultivated in residual frying palm oil. It is a naturally immobilized lipase with protein content of 47%, herein called LipImDebri. This immobilized biocatalyst presents low hydrophobicity (8%), that can be increased adjusting pH and buffer type. Despite apparent intact cells, electron microscopy showed a shapeless and flat surface for LipImDebri and optical microscopy revealed no cell viability. Besides, an inferior mean diameter (3.4 mm) in relation to whole cells reveals structure modification. A high negative zeta potential value (− 33.86 mV) for pH 6 and 25 °C suggests that LipImDebri is a stable suspension in aqueous solution. Fourier Transform Infrared Spectra (FTIR) expose differences between LipImDebri and extracellular lipase extract signaling a physical interaction between enzyme and cell debris, which is possibly the reason for the high thermostability ( k d  = 0.246 h −1 ; t 1/2  = 2.82 h at 50 °C, pH 7.0). A good adjustment of LipImDebri kinetic data with Hill equation ( R 2  = 0.95) exposes an allosteric behavior related to the presence of more than one lipase isoform. These features reveal that LipImDebri can be a good catalyst for industrial applications.