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The effect of activated carbon on the organic and elemental composition of plant tissue culture medium

by Van Winkle, Stephen C.

Abstract (Summary)
This research was motivated by differences in plant tissue culture success when using growth media with different activated carbons (non-acid washed vs. tissue culture grades). The primary research objective was to correlate the physical or chemical character of activated carbon with its impact on the elemental and hormonal composition of tissue culture medium, and hence with culture success. A bioassay (Norway spruce initiation) was developed based on a liquid medium containing activated carbon (0.3 g/L). Activated carbon was characterized using standard techniques. Elemental composition of media was quantified by inductively coupled plasma atomic emission spectroscopy and capillary ion electrophoresis. Hormonal composition was measured using UV spectroscopy and high performance liquid chromatography. Of the mineral elements present in the growth medium, only copper and zinc were adsorbed onto activated carbon, ca. 95% and 50%, respectively. Extent of adsorption was similar for non-acid washed and tissue culture grades of activated carbon. The elemental composition of the medium was more sensitive to the system pH than to differences in activated carbon character, with marked precipitation of elements in response to increased pH (from 5.8 to 6.5): iron (-33%), manganese (-40%), phosphorus (-15%), and zinc (-28%). Precipitation was reversible. Media formulated with reduced levels of Fe, Mn and P gave reduced success of the bioassay (-20%). In single-hormone adsorption experiments (constant pH 5.8), 6-benzylaminopurine (BAP) adsorbed to twice the level of 2,4-dichlorophenoxyacetic acid (2,4-D). When both hormones were present, BAP adsorption was similar to its single-solute case, while 2,4-D adsorption was greatly reduced. 2,4-D adsorption varied with pH over the normal tissue culture pH range, explained through solubility and pKa . Hormone adsorption was linearly correlated to activated carbon surface area (BET) and total pore volume with r2 values exceeding 0.97. On a per-mass basis, at constant pH, total pore volume accounted for approximately 95% of the hormone adsorption for eight different activated carbons. The bioassay was more sensitive to different hormone levels than to the observed differences in elemental composition. Therefore, the critical material characteristic when using different tissue culture grades of activated carbon is their relative total pore volumes.
Bibliographical Information:

Advisor:Institute of Paper Science and Technology

School:Georgia Institute of Technology

School Location:USA - Georgia

Source Type:Master's Thesis

Keywords:institute of paper science and technology

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