The 8
th
International Conference
May 19–20, 2011, Vilnius, Lithuania
Selected papers
ISSN 2029!7106 print / ISSN 2029!7092 online
ISBN 978!9955!28!826!8 (1 Volume)
ISBN 978!9955!28!827!5 (3 Volumes)
© Vilnius Gediminas Technical University, 2011
25
! "#$# %$#&%’#
(
! #)# *#
+
! ,’# $-#.-#
/
! ,0# .$
1
1, 2, 3, 4, 5
!"#$%&
’"(
5
()*
4
+ , - . !"/00#
)$#2$ Historically 2,4,6!Trinitrotoluene (TNT) was the most widely used military explosive. TNT is toxic and
mutagenic compound, having a serious impact on the environment. The aim of this study was to evaluate an effi!
ciency of bioaugmentation in combination with nutrient amendments and rye -. Design of 30!days soil col!
umn experiment provided the control of nitroaromatics (NA) distribution from topsoil (4cm) to deeper layers of soil
horizon (20cm). For bioaugmentation, consortium with 5 isolates belonging to 1( and -"
( ( was used. For biostimulation, molasses and plant extract was added to soil. At the begin!
ning of the experiment, only topsoil was contaminated with TNT and its degradation products (75mg NA/kg). After
30 day experiment, the NA concentration in soil amended with nutrients and bacteria consortium was decreased in
topsoil from 75 mg/kg to ~4 mg/kg. In the sets with planting rye and nutrient amendments, NA migration to deeper
layers of soil horizon was detected. To compare microbial activity in different experimental sets, enzymatic activity
(i.e. fluoresceine diacetate hydrolysis, FDA) was measured. After 30!days experiment, FDA activity in soil with bac!
teria consortium was two!fold higher, as compared to non!augmented soil. An increase of microbial enzymatic activ!
ity was detected only in topsoil. Growth of rye was more active in the presence of bacteria consortium. In turn, TNT
and its degradation products inhibited plant development. Thus, the results of this experiment indicated to the active
role of bioaugmentation and biostimulation in the process of NA degradation. In turn, the growth of rye in the pres!
ence of nutrient amendments was not efficient in terms of NA biodegradation.
"34%5 bioaugmentation, biodegradation, enzymatic activity, explosives, plant growth, soil column experiment.
))’#$%5 Am – nutrient amendments; AM!5 – bacteria consortium; CFU – colony forming units; FDA – fluo!
resceine diacetate; NA – nitroaromatic compounds; TNT – 2,4,6!Trinitrotoluene.
$%.2$%
Historically TNT was the most widely used military
explosive. TNT is toxic and mutagenic compound, having
a serious impact on the environment. biodegradation
of nitroaromatic compounds is known as very complex
process, which depends on many environmental factors.
Among these factors are the composition and concentration
of NA, soil properties, aeration, climatic conditions (tem!
perature, humidity etc.), microbial community, presence of
co!substrates etc. These factors influence the process dy!
namics separately and in synergistic interrelations. There
are three main biotechnological approaches known for
bioremediation of soils contaminated with explosives, i.e.
biostimulation, bioaugmentation and phytoremediation.
Each of these approaches requires deep knowledge and
special experience. Application of these approaches to!
gether in different combinations leads to drastic changes in
biodegradation process as compared to the processes where
these approaches are used separately. Moreover, such a
combination of different approaches can lead to unex!
pected, not always positive results.
The phytodegradation of organic compounds can
take place inside the plant or within the rhizosphere of the
plant. Many different compounds and classes of com!
pounds can be removed from the environment by this
method, including aromatic compounds in soils (Newman
and Reynolds 2004). Planting with Johnsongrass or wild
ryegrass resulted in a decrease of TNT concentrations in
soil (Sung 2003). Different plants are used to reme!
diate surface waters contaminated with TNT and could
reduce toxicity in the system (Hitchcock . 2003). In
many cases, plant strategy used to grow on soils contami!
nated with TNT is based on metabolization and immobi!
lization of TNT in roots (Vila 2007). Studies with
plants have demonstrated their ability to transform TNT
to monoaminodinitrotoluenes and unidentified com!
pounds more polar than TNT (Sun 2000).
Degradation of toxic organic compounds in soil by
plant!associated bacteria can involve endophytic and