Environmental Fate and Transport of Solvent-Stabilizer Compounds - Environmental Investigation and Remediation - page 163

FIGURE 3.5 Light micrograph of C. sinensis Strain A. (From Nakamiya, K., et al., 2005, Applied and
Environmental Microbiology 71(3): 1254-1258. With permission.)

Nakamiya et al. applied an innovative technique, reacting phenyl boronate with the degradation
products, to identify the products of C. sinensis biodegradation of 1,4-dioxane. Phenyl boronate
forms ether bonds with dihydroxy compounds in water-methanol; the derivatives are amenable to
gas chromatography/mass spectrometry analysis. By analyzing the breakdown products, Nakamiya
et al. were able to propose a degradation pathway for i lamentous fungus degradation of 1,4-dioxane,
as shown in Figure 3.6. The pathway follows the sequential production of ethylene glycol, glycolal-
dehyde, glycolic acid, and oxalic acid followed by incorporation of the glycolic acid and/or oxalic
acid into the tricarboxylic acid cycle. This study proposed etherases and oxidases as the likely
enzymes involved in C. sinensis degradation of 1,4-dioxane by Strain A, as shown in Figure 3.7 . The

0.08 1.2

1, 4-dioxane

70

Protein

0.07

Ethylene glycol

1

60

0.06

50 0.8

0.05

40

0.04 0.6

30

0.03

0.4

20

0.02

10 0.2

0.01

0 0

0 20 40 60 80 100 120

Time (h)

FIGURE 3.6 Rates of 1,4-dioxane degradation and product formation by C. sinensis . (From Nakamiya, K.,
et al., 2005, Applied and Environmental Microbiology 71(3): 1254-1258. With permission.)