Use of Chlorella vulgaris (Chlorophyceae) to test wood preservatives at a laboratory scale

GAGNETEN, AM.; MURGUIA, M.C.; ORMAECHEA, A.; RENO, U. ; REGALDO, L.

Berlin

Congreso; 6th SETAC world Congress ? SETAC Europe 22nd Annual Meeting.; 2012

SETAC WORLD - SETAC EUROPE

Most of the surfactants and antimicrobials are discarded after use in industrial effluents or sewage and can reach rivers, lakes and oceans, driving the development of new surfactants that are less harmful to the environment. We present the results obtained after testing a novel wood preservant compound through acute and chronic toxicity tests using Chlorella vulgaris (Chlorophyceae).Two compounds were studied: a gemini synthesized and isolated at the laboratory (A5D, 80-85% purity), and a TCMTB based commercial (solution 30%). TCMTB is an oil soluble active agent used to preserve wood, very efficient due to its high penetrating power. We calculated the growth rate (μ) (PROBALG2 program), the percentage of growth inhibition (%I) and EC50 96h for each of the compounds, all essays with three replicates per concentration. With TCMTB the following concentrations were tested: 1.562 x 10-4 ml/l, 3.125 x 10-4 ml/l, 6.250 x 10-4 ml/l, 1.250 x 10-3 ml/l, 2.5 x10-3 ml/l, 5 x 10-3 ml/l, 0.01 ml/l, 0.02 ml/l and a control. A5D gemini concentrations were: 0.32 mg/l, 0.64 mg/l, 1.68 mg/l, 2.56 mg/l, 5.12 mg/l, 10.24 mg/l, 20 mg/l, 48 mg/l and a control. The culture conditions were constant, continuous illumination with white light 3000 lux, 23±1°C.With TCMTB we obtained: EC50 = 2.172 x 10-4 mg/l. Between the lowest and the highest concentration we obtained 50.300 and 4000 cells/ml; μ between 0.0096 and -0016 and (%I) between 36 and 206.With the gemini compound we obtained: EC50 = 0.6568 mg/l (three orders of magnitude smaller than the commercial product). Between the lowest and the highest concentrations we obtained between 4800 - 54400 cells/ml; μ between 0.010 and -0.014 and (%I) between 33.0 and 193.3. These results highlight the importance of promoting the synthesis of compounds less harmful to the environment.