Student name: Salla Leppäkoski

RUN-EU institution: Häme University of Applied Sciences, Finland

Abstract

Seaweed Ulva spp. is used for food, feed, pharmaceuticals, biofiltration, biofuels and biostimulants. Seaweed over-harvesting can lead to environmental problems, which can be reduced by cultivating seaweed in controlled systems. In addition, seaweed’s biomass production and biochemical profile can be optimised in controlled cultivation. Challenge in controlled seaweed cultivation is colonisation by micro-organisms. This study evaluated the suitability of various sterilisation agents for reducing and eliminating contaminations in Ulva spp. cultures. Samples of Ulva spp. were collected from Batel beach, Portugal and exposed to three different sterilization agents (NaOCl, EtOH and Triton X-100) with different exposure times (from 30 s to 10 min). Sterilised pieces of Ulva spp. were placed on Petri dishes and kept in temperature-controlled room. Chlorophyll loss and the presence of contaminants were observed for three days. Triton X-100 for 30 s exposure time was found to be the most effective sterilisation agent for Ulva spp. without causing chlorophyll loss. NaOCl (1-3% for 30-60 s) removed contaminants but chlorophyll loss was detected. However, with this treatment reproductive cells were observed, which makes it an interesting alternative for continuous cultivation. EtOH was found to be inefficient for sterilisation.