淡水河口紅樹林沈積物中脫氮細菌之研究

This work investigated denitrifying
bacteria and their denitrifying activity in the
sediment from forests of the mangrove
Kandelia candel in the Tansui Estuary. The
samples were collected from Watsuwe 、
Chuwei and Kuantu. Effects of nitrate,
glucose, NaCl and temperature on the
denitrifying (N2O-producing) activity of the
sediment samples were determined by the
acetylene blockage technique. Nitrous oxide
(N2O) was never detectable unless the
samples were supplemented with both nitrate
and glucose. The levels of such potential
denitrifying activity did not greatly differ in
NaCl concentrations ranging from 0 to 3.5%.
All the samples supplemented with both
nitrate and glucose exhibited detectable
activity within 12h incubation at 35 or 40℃.
However, activity was not detected from any
of those incubated at 20 ℃ , and those
incubated at 25 or 30℃ exhibited nil or
relative low levels of activity. Insufficiency
of both nitrate and organic matter would be
apt to restrict the magnitude of in situ
denitrification in the sediment of the
mangrove forests. Salinity is probably not a
limiting factor for the activity, whereas low
temperature in the seasons other than summer
would be a main factor limiting the
expression of denitrifying activity.
Denitrifying bacteria distributed in the
mangrove forest sediment were enumerated
by the most-probable-number (MPN) method
2
in liquid broth. The counting values ranged
from 104 to 105 cells/g wet wt.. Twenty-nine
rods-shaped, denitrifying bacteria isolated
from the sediment samples were divided into
three group according to the tests of Gram
reactions、fermentation、motility and salt
requirement. Twenty-six salt-requiring
Gram-negative strains were identified as
members of the group Alteromonas-
Pseudomonas- Deleya. The other three strains
that did not require salt for growth were
identified as species of either Pseudomonas
(two strains) or Bacillus (one strain).