Agriculture Reference
In-Depth Information
Each 320-ml solution of 1000-fold-diluted seaweed culture broth or of the commercial liquid
fertilizer was added underneath the plastic screen to fully soak the seeds. Each prepared pot
was covered with aluminum foil to keep the seeds in the dark. After the seeds germinated, all
the pots were placed by the window all day to provide enough sunlight for plant growth.
Light from two light bulbs (100 W) that were placed 50 cm from the pots was provided
instead on cloudy days. The air temperatures at day and night were maintained at
approximately 24 and 18 °C, respectively, by natural ventilation and heating. The water
temperature was approximately 17 °C, and the relative humidity in the culture room was
approximately 65% on average . Each solution of the culture broths or commercial liquid
fertilizers was refreshed every 3 d. Measurements of plant growth (stem height, stem
thickness, leaf number and leaf length) were periodically performed for both kidney bean and
barley.
Analyses
The cell density, which indicates the number of viable cells, was measured after the
samples were diluted and plated on nutrient agar. Cell density is expressed as colony forming
units (CFU) per ml of sample. The concentrations of COD Cr and TN were analyzed by a
water-quality analyzer. The concentrations of Na + , NH 4 + , Cl - , NO 2 - , NO 3 - , and PO 4 3- were
estimated by ion chromatography (Metrohm 792 Basic IC, Switzerland). The columns that
were used in these analyses were Metrosep C2-150 (150×4.0 mm) and Metrosep Supp 5-150
(150×4.0 mm) for cations and anions, respectively.
All measurements were performed in triplicate. The composition of amino acids and
heavy metals in the culture broth of each seaweed was analyzed at the Korea Basic Science
Institute (Seoul, Korea).
The characterization of the microorganisms' ability to degrade each seaweed was
deduced from the quantity of reducing sugars. Thin-layer chromatography (TLC) was also
used to differentiate and identify various seaweed-decomposition products. The reducing
sugars were quantified by the 3,5-dinitrosalicylic acid (DNS) method (Chaplin & Kennedy,
1986), using glucose as the standard substrate for green seaweed and brown seaweed
polysaccharides and using galactose as the standard substrate for red seaweed
polysaccharides. TLC was performed by the ascending method, using Silica Gel-60 TLC
plates (E. Merck, Darmstadt, Germany). n-butanol:acetic acid:water (2:1:1), n-
butanol:ethanol:water (3:2:2) and n-butanol:isopropanol:ethanol:water (2:3:3:2) solutions
were used to develop the green seaweed, red seaweed and brown seaweed decomposition
products on the TLC plates, respectively.
The products that were depolymerized from green seaweed polysaccharides were
visualized by heating at 120 °C for 15 min, after spraying with 10% (v v -1 ) H 2 SO 4 in ethanol.
The products that were depolymerized from red seaweed polysaccharides were visualized by
heating at 110 °C for 10 min, after spraying with 0.2% naphthoresorcinol solution and 10% (v
v -1 ) H 2 SO 4 in ethanol. The products that were depolymerized from brown seaweed
polysaccharides were visualized by heating at 110 °C for 20 min, after spraying with 10% (v
v -1 ) H 2 SO 4 in ethanol.
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