Induction of phlorotannins during UV exposure mitigates inhibition of photosynthesis and DNA damage in the kelp Lessonia nigrescens.

Phlorotannins of brown algae are multifunctional compounds with putative roles in herbivore deterrence, antioxidation and as primary cell wall components. Due to their peripheral localization and absorption at short wavelengths, a photoprotective role is suggested. We examined the induction of phlorotannins by artificial UV radiation in the intertidal kelp Lessonia nigrescens and whether they attenuate the inhibition of photosynthesis and DNA damage, two major detrimental effects of UV. The soluble and cell wall-bound fractions of phlorotannins were quantified in blades collected in summer and winter. Major findings were that (1) the synthesis of phlorotannins (both forms) was induced by UV only in summer; (2) the induction was fast (within 3 days); and (3) there was a positive relationship between of the contents of insoluble phlorotannins and the suppression of photoinhibition and DNA damage, measured as formation of cyclobutane pyrimidine dimers and 6-4 photoproducts. Overall, the photoprotective role of phlorotannins appears to respond to an interplay between the external UV stimulus, seasonal acclimation and intrinsic morpho-functional processes. In summer, when algae are naturally exposed to high UV irradiances, soluble phlorotannins are induced, while their transition to insoluble phlorotannins could be related with the growth requirements, as active blade elongation occurs during this season.

Bioconversion of apple pomace into a multienzyme bio-feed by two mixed strains of Aspergillus niger in solid state fermentation

Apple pomace is a wasted resource produced in large quantities and its deposit has caused serious environmental problems, so it is significance to make the full utilization of the residues. The objectives of this work were to produce multienzyme bio-feed, biodegrade the anti-nutritional factors such as pectin and tannins in apple pomace, and obtain the nutritional enrichment of the fermented substrate. The mixture of apple pomace and cottonseed powder (1:1, w/w), supplemented with 1 percent (w/w) (NH4)2SO4 and 0.1 percent (w/w) KH2PO4, was proved to be the optimum medium for the mixed strains of Aspergillus niger M2 and M3 (2:1, w/w). The activities of pectinase, proteinase and cellulase achieved 21168 u/g, 3585 u/g and 1208u/g, and the biodegradation rates of pectin and tannins reached 99.0 percent and 66.1 percent, respectively, when 0.4 percent(w/w) of the test fungiwere inoculated and incubated at 30ºC for 48 hrs in solid state fermentation. The utilization of apple pomace in the paper can be served as a model for the similar waste recycling.