Production and action pattern of inulinase from Aspergillus Niger-245: hydrolysis of inulin from several sources

Abstract

A strain of Aspergillus niger isolated from soil samples showed great capacity to produce extracellular inulinase. Although the enzyme has been synthesized in presence of monosaccharides, sucrose and sugar cane molasse, the productivity was significantly higher (p<0.05) when the microorganism was inoculated in media formulated with dahlia extract and pure inulin, as carbon sources. With regard to the nitrogen source, the best results were obtained with casein and other sources of proteic nitrogen, comparatively to the mineral nitrogen. However, statistic significance (p<0.01) only was found between the productivity obtained in the medium prepared with casein and ammonium sulphate. The optimum pH of the purified enzyme for inulin hydrolysis was found between 4.0 and 4.5 and the optimun temperature at 60oC. When treated by 30 minutes in this temperature no loss of activity was observed. The enzyme showed capacity to hydrolyse sucrose, raffinose and inulin from which it liberated only fructose units showing, therefore, an exo-action mechanism. Acting on inulins from several sources, the enzyme showed larger hydrolysis speed on the polissaccharide from chicory (Cichorium intibus), comparatively, to the inulins from dahlia (Dahlia pinnata) and Jerusalem artichoke (Helianthus tuberosus) roots.

Aspergillus niveus Blochwitz 4128URM: new source for inulinase production

“…At 15 and 20 g L -1 inulin concentrations, the biosynthesis of inulinase occurred in log phase of the growth. Cruz et al(1998) observed a similar behavior for A. niger 245, which showed inulinase production in the log phase between 24 h and 60 h. Poorna and Kulkarni (1995) obtained, working with the same species, maximum growth in 48 h and maximum inulinase production in the log phase between 48 h and 60 h. The inulinase production by A. niveus 4128URM was shown to be dependent of the inulin concentration and fermentation time. In the studied range, the maximum inulinase activity was significantly superior (P<0.05) at inulin concentrations of 15 g L -1 (8.71 U mL , the maximum inulinase activity was significantly lower (2.63 U mL -1 ) at 24 h, showing decrease after this period probably due the diauxic phenomena presented in this concentration.…”

“…Ongen-Baysal et al(1994) found best results at pH between 5.0 and 6.0 at 50 ºC and Cruz et al(1998) at pH 4.0 to 4.5 at 60 ºC. Some species of Aspergillus produce inulinases with maximum activity at higher temperatures, such as A. niger 245 at 60 ºC (Cruz et al, 1998). However, temperatures above 55 ºC could inactivate some inulinases produced by fungi (Vandamme and Derycke, 1983), a fact that occurred with the inulinase of A. niveus 4128URM, when incubated at 60 ºC.…”

“…Derycke and Vandamme (1984) obtained higher inulinase activity at pH 4.4 and 4.6 at temperatures of 55 ºC and 56 ºC. Ongen-Baysal et al(1994) found best results at pH between 5.0 and 6.0 at 50 ºC and Cruz et al(1998) at pH 4.0 to 4.5 at 60 ºC. Some species of Aspergillus produce inulinases with maximum activity at higher temperatures, such as A. niger 245 at 60 ºC (Cruz et al, 1998).…”

“…Among the filamentous fungi, species of Aspergillus described in the literature are A. aureus, A. fischeri, A. flavus and A. nidulans (Gupta et al, 1994a), A. awamori (Zherebtsov et al, 1995), A. candidus (Kochhar et al, 1999), A. niger (Derycke and Vandamme, 1984;Ongen-Baysal et al, 1994;Wallis et al, 1997;Cruz et al, 1998;Nguyen et al, 1999), A. oryzae and A. versicolor (Kochhar et al, 1997). Till now, however, there is no report on inulinase production from A. niveus.…”

Partial characterization of an inulinase produced by Aspergillus japonicus URM5633

“…Some species of Aspergillus produce inulinases with maximum activity at higher temperatures. For example, the inulinase from A. niger 245 has optimal activity at 60ºC (Cruz et al 1998). However, temperatures above 55ºC may disable some inulinases that are produced by fungi (Vandamme and Derycke 1983b).…”