humic substance and aquatic microbial ecology ahn, tae-seok
DESCRIPTION
Humic substance and aquatic microbial ecology Ahn, Tae-Seok. Introduction. v DOC and POC Most allochthonous dissolved organic carbon (DOC) and particle organic carbon (POC) in aquatic ecosystem are coming from terrestrial ecosystem v DOC From exudate (Rhizosphere) - PowerPoint PPT PresentationTRANSCRIPT
Humic substance and aquatic microbial ecology
Ahn, Tae-Seok
v DOC and POC
• Most allochthonous dissolved organic carbon (DOC) and particle organic carbon (POC) in aquatic ecosystem are coming from terrestrial ecosystemv DOC• From exudate (Rhizosphere)• Resultant of microbial degradation v POC• From debris of plant (lignin, cellulose from leaves, wooden particles)
Therefore, The characteristics of DOC and POC depend on land
use
More over Dissolved humic substances (HS) comprise 50-80 % of DOC in aquatic ecosystem (Farjalla et al, 2009)
IntroductionIntroduction
A. HS is biologically inert in aquatic ecosystem
B. Ecological function of HS is related to iron, phosphate bioavailability, pH condtion and light penetration (Steinberg et al 2008)
C. DOC and HS enter planktonic food web through Microbial Loop (Azam et al 1983), and are important source of energy and matter
IntroductionIntroduction
D. HS is consisted with acidic materials, so the streams and lakes with HS are acidic state
E. Acidic lake (pH about 4) in Japan zooplankton is abundant, but there is no phytoplankton.
IntroductionIntroduction
IntroductionIntroduction
Zooplankton are eating bacteria and phytoplankton
Red: phytoplanktonBlue: bacteria stained with DTAF
These microphotographys are evidence of the MICROBIAL LOOP
(Sim and Ahn, 1983)
G. HS is coming from forest, low nutrient concentration
IntroductionIntroduction
Brown colored HS in stream of forestJuly, 2009, Forest near Bayreuth
H. Another source of HS is coming from poultry waste, with high concentration of nutrient
IntroductionIntroduction
Over flow of black colored waste water form poultry June 2006, Pusan, Korea
HS + N, PEnergy and
Nutrientsupply
Bacteria
HS
Energy ?P source ?
Phytoplankton
Low pH
inhibits Exudatestimulates
Zooplankton
grazing
grazing
FISH
Natural source
Waste water
Over growth= Saprobic state
Stimulates=Eutrophication
HS vs Microbial loop
1. Bacterial community structure in HS conatinning stream and poultry waste water
MethodsMethods
Total bacterial number (Invitrogen, 1998)Community with DGGE & FISH method β-glucosidase & phsophatese activities (Chróst, 1989) -MUF method
Profiles of microbial community by DGGE
MethodsMethods
Samples
DNA extraction
TotalsampleDNA
PCR
PCRamplicon
DGGE
Community Fingerprinting
Sequence analysis
Phylogenetic &
functional diversity
Detection of Bacillus by fluorescent in situ hybridization (FISH)
MethodsMethods
Probe name probe sequence
S-G-Bacill-0597-a-A-22 5’-GGGTCATTGGAAACTGGGGAAC-3’
Hybridization : 45 , 4 hrs, ℃ Washing : 45 , 20 min℃
Bacillus sp. from Lake Baikal by FISH
2. Role of HS in aquatic ecosystem
MethodsMethods
After addition of HS containing water to natural lake water, and the change of bacterial community and activity will be analyzed
Grazing behavior of Zooplankton will be defined
Expected Expected resultsresults1. Microbial availability of HS
• HS is source for energy and matter…. So by the changes of enzymatic activities
hypothesis : if phosphatase activity is increasing=HS would be source for phosphate
if glucosidase activity is high=HS is for energy
2. Profile of microbial community
• HS would be acting as trigger for bacterial succession = how? What is the effects?
Expected Expected resultsresults3. Different effect of nutrient rich or poor
HS to aquatic ecosystem Do Zooplankton change their grazing behavior by
HS ? And nutrient is effecting for grazing behavior? If that what is the machanism?