Polyextremophilic Chitinolytic Activity by a Marine Strain (IG119) of Clonostachys  rosea

Abstract

The investigation for novel unique extremozymes is a valuable business for which the marine environment has been overlooked. The marine fungus Clonostachys rosea IG119 was tested for growth and chitinolytic enzyme production at different combinations of salinity and pH using response surface methodology. RSM modelling predicted best growth in-between pH 3.0 and 9.0 and at salinity of 0-40‱, and maximum enzyme activity (411.137 IU/L) at pH 6.4 and salinity 0‱; however, quite high production (>390 IU/L) was still predicted at pH 4.5-8.5. The highest growth and activity were obtained, respectively, at pH 4.0 and 8.0, in absence of salt. The crude enzyme was tested at different salinities (0-120‱) and pHs (2.0-13.0). The best activity was achieved at pH 4.0, but it was still high (in-between 3.0 and 12.0) at pH 2.0 and 13.0. Salinity did not affect the activity in all tested conditions. Overall, C. rosea IG119 was able to grow and produce chitinolytic enzymes under polyextremophilic conditions, and its crude enzyme solution showed more evident polyextremophilic features. The promising chitinolytic activity of IG119 and the peculiar characteristics of its chitinolytic enzymes could be suitable for several biotechnological applications (i.e., degradation of salty chitin-rich materials and biocontrol of spoiling organisms, possibly solving some relevant environmental issues).

Keywords: Clonostachys rosea; chitinolytic enzymes; high producer; marine fungi; polyextremophiles; response surface methodology.

Figure 1

Clonostachys rosea IG119 growth (a) and enzyme activity (b) in static and shaken cultures.

Figure 2

Box plots of radial growth by Clonostachys rosea IG119 on solid media. (a) Growth at different salinities at pH 8. (b) Growth at different pHs and salinities. All data collected daily during the experiment (16 days) were standardized on daily maximum. The same greek letters over the boxes indicate not significant differences among data, as determined by the post hoc test (p < 0.005).

Figure 3

Single (a) and combined (b) effects of different pHs and salinities on the biomass production by Clonostachys rosea IG119 as reported by the RSM model.

Figure 4

Single (a) and combined (b) effects of different pHs and salinities on the chitinolytic enzyme production by Clonostachys rosea IG119 as reported by the RSM model.

Figure 5

Effect of pH on the Clonostachys rosea IG119 crude enzyme activity.

Figure 6

Activity of Clonostachys rosea IG119 crude extract in polyextremophilic conditions.