Comparison Of LED And Fluorescent Lighting In The Culture Of

1. Comparison Of LED And Fluorescent Lighting In The Culture Of Wild And Green Mutant Strains Of Gracilaria Tikvahiae George Kraemer1, G. Yunxiang Mao2,3, Jang Kim3, Charles Yarish3 1Environmental Studies Program, Purchase College (SUNY), 2College of Marine Life Sciences, Ocean University of China, Qingdao, 3Ecology and Evolutionary Biology, University of Connecticut, Stamford • Rising energy costs require energy efficient operations • Light emitting diode (LED) performance has increased ca. 30-fold per decade since 1970, while operating costs have decreased by a factor of 10 per decade; • Application of LED technology has significant advantages over other light sources: Energy efficiency, low emitting temperature, small size, long lifetime; • Globally, aquaculture is a $USD 7 billion industry, in which the United States plays a minor role; • We investigated the efficacy of LEDs in generating biomass in support of our field aquaculture operations using the agarophyteGracilaria tikvahiae ; • Study Objectives: • To compare growth and pigment levels of a wild and a green mutant strain of G. tikvahiae under: • fluorescent lighting (control) • pure primary color (red, green, or blue) LEDs • mixed LEDs INTRODUCTION RESULTS Fig. 1 Fig. 4 Fig. 5 Growth of the wild strain was 11% higher than green mutant under fluorescent light (monochromatic experiment; Fig. 1). Pooled over all experiments, growth rates of the two strains were indistinguishable (p = 0.35; data not shown). The pattern of growth was similar for both strains (F > (R = G) > B). The green mutant, however, grew significantly (45%) slower under pure blue LED light than did the wild strain (p = 0.0068). Letters indicate statistical difference Tissue of the green mutant possessed lower pigment levels, except for phycocyanin (growth under fluorescent light; Fig. 4). Chlorophyll and carotenoid levels co-varied similarly in both strains under all light regimes (Fig. 5). Fig. 2 Fig. 3 Fig. 6 Phycoerythrinand phycyocyanin levels co-varied differently in each strain under all light regimes (Fig. 6). Gracilaria tikvahiae strains (wild, green mutant) were obtained from the UConn Stamford Culture Collection. Strains originated locally (Long Island Sound). A starting biomass of 0.2 g FW was placed in 100 mL cylindrical glass jars and incubated in nutrient-replete VSE media (changed every 3-4 days) at 100 µmoles photons m-2 s-1 under each light source for 16 (green mutant) to 21 (wild type) days. T4 tubes provided fluorescent light from above cultures. LED arrays were placed around the inside of PVC cylinders. Measurement of final biomass enabled calculation of growth rate (% d-1). Tissue pigment levels (chlorophyll, carotenoids, phycoerythrin, phycocyanin) were measured using standard methods (extraction and spectrophotometry). METHODS CONCLUSIONS Growth rates of G. tikvahiae are higher under fluorescent light than primary color LED. Color blends (≥20% of each primary color) equalized growth rate and tissue chlorophyll levels. The wild and green mutant strains exhibited gross differences in pigment levels. The wild and green mutant strains differ in the phycoGiven #2, above, economics and environmental issues argue strongly for the use of LED in algal culture: The pattern of growth of the wild strain (F > (R = G) > B) was reduced with mixing of two primary color LEDs, and the differences disappeared with increasing primary color blends (letters indicate statistical difference). Tissue chlorophyll levels were higher under green-only and Red+Blue LED (Fig. 4). When all three primary colors were supplied (regardless of percent), tissue chlorophyll levels were indistinguishable (letters indicate statistical difference).