• Keine Ergebnisse gefunden

The  Resazurin-­‐Agar  Method:    A  Quick  Test  to  Determine  Water  Quality  

N/A
N/A
Protected

Academic year: 2022

Aktie "The  Resazurin-­‐Agar  Method:    A  Quick  Test  to  Determine  Water  Quality  "

Copied!
1
0
0

Wird geladen.... (Jetzt Volltext ansehen)

Volltext

(1)

SFB 754

The  Resazurin-­‐Agar  Method:    A  Quick  Test  to  Determine  Water  Quality  

Jonas Huckfeldt*, Lisa Claußen and Bjarne Westphal Humboldt- Schule Kiel

GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany

Structure-of-Resazurin-

Structure of Resazurin

Resazurin  is  a  blue  redox-­‐indicator  which  turns  irreversibly  to  the  pink  coloured  resorufin  when  reduced  by  bacteria.  Thus   the   degree   and   speed   of   colour   change   is   an   indica>on   of   microbial   ac>vity   and   bacterial   numbers.   We   tested   the   suitability  of  resazurin  agar  plates  to  test  the  microbial  ac>vity  in  small  volumes  of  different  water  samples.    

Laboratory  Tests  

•  The  resazurin  was  reduced  in  the  presence  of  yogurt  bacteria   in  the  filters.    

•  A  discoloura>on  gradient  with  regard  to  the  concentra>on  of   bacteria  was  recognizable.  

•  A  strong  contamina>on  by  foreign  bacteria  caused  reduction of resazurin and resorufin in the plates after 78 hrs.

Preliminary   experiment   using   a   stock   suspension   of   yogurt   bacteria   was   prepared.   Different   dilu>ons   of   the   suspension   were  placed  onto  filters  and  the  filters  were  placed  face  down  on   the  resazurin  agar  plates.  

24 hrs

78 hrs

•  The  test  is  quick.  Results  are  obtainable  within  24  hours  as  compared  to  other  screening  tests  like                BOD  (Biological  Oxygen  Demand),  which  need  several  days  before  results  can  be  evaluated.  

•  It  is  simple  and  can  be  performed  with  a  minimum  of  effort  and  expense,  with  several  screenings            cos>ng  less  than  $1.  

•  Using  cell  well  plates,  mul>ple  assays  can  be  done  simultaneously  lessening  the  >me  for  processing   numerous  samples.  

•  The  test  can  be  used  for  freshwater  and  marine    environmental  samples.    

•  The  method  is  very  simple  and  can  thus  be  adopted  for  microbiology  and  ecology  lessons  in  schools.  

The  Resazurin-­‐  Agar-­‐  Method  for  es>ma>ng  microbial  ac>vity  and  thus  water  quality  has  several  advantages  :    

Lake  Water  Samples  

•  More  reduced  resazurin  was  observed  in  the  sample  from  the  site   where   the   water   was   warmer.   The   higher   temperatures   there   might  have  caused  faster  mul>plica>on  of  the  bacteria  leading  to   higher  numbers  of  microbes.    

 

•  Cell  wells  were  found  to  be  prac>cal  for  this  kind  of  test,  enabling   mul>ple   assays   with   different   water   samples.   This   also   makes   comparison  of  water  samples  easier.    

The   method   was   verified   using   bacteria   collected   from   2   different   sources   in   a   pond.   One   source   was   near   a   sub-­‐surface   pipe   which   drains   warm   water   into   the   pond.   The   second   source   was   on   the   opposite  side  of  the  pond,  where  the  water  is  colder.    

Start

61 hrs

Seawater  Samples  

Water   samples   from   different   depths   at   two   sta>ons   in   the   Bal>c   Sea   were   collected   and   filter   frac>onated   to   separate   different   sizes   of   bacteria.   The   oxygen   concentra>ons   at   the   sta>ons  were  measured  separately  using  the  Winkler  method.    

•  In   water   samples   collected   from   the   sta>on   with   lower   oxygen   concentra>ons   a   higher   resazurin   reduc>on   was   observed.  High  microbial  ac>vity  may  have  contributed  to  the   low  oxygen  levels  at  the  sta>on.    

 

•  Water  samples  collected  lower  in  the  water  column  showed   higher  microbial  ac>vity.  

•  Par>cles   collected   on   the   3.0   μm   filter   showed   higher   resazurin   reduc>on   probably   due   to   bacteria   aYached   to   sinking  organic  maYer.    

O 2-concentration (ppm) 8,45

8,30

O2 -concentration (ppm) 7,65

7,25

Surface

Mid depth

Bottom

0,2 0,45 0,8 3,0 0,2 0,45 0,8 3,0

Sta>on  1   Sta>on  2  

Filterpore  size  (μm)  

* Corresponding Author: Jonas Huckfeldt jonas.huckfeldt@web.de

Start

1   3   2  

4   5   6

8 7

9   10   11  

Materials  used  for  making  the  agar  plates  

Informa>on:  

 

The  numbers  indicate   decreasing  

concentra>ons  of   bacteria  in  the  filters.  

Each  step  corresponds   to  ½  dilu>on  of  the  

preceeding  step.    

 

Discoloura>on  was     more  intensive  in  the   lower  numbers  aber  24  

hours.    

Study  site  

Water  samples  were  collected  on  board  a   research  vessel  (A)  from  different  depths   with  a  RoseYe  water  sampler  (B  &  C).  

A  

B   C  

Filter  frac>ona>on  of  the  water  samples   Sample  collec>on  sites:  

(1)  warm  water  (red   arrow)  and  (2)  cold   water  (blue  arrow)   (1)    

(2)    

26 hrs

Site  2  

Samples  were  diluted  with  dis>lled  water  

                 decreasing  dilu>on  of  sample   Site  1  

Water  samples  

Referenzen

ÄHNLICHE DOKUMENTE

The ACHE stock solution activity and kinetics of ATCH hydrolysis were measured by the Ell- man’s method at pH 8, ionic strength I = 0.11 m (ensured by concentration of buffer) and 25

As an example for the usage of our test specification quality model instantiation for TTCN-3, we applied it to several versions of a TTCN-3 test suite for testing the con- formance

The method is based on a Branch and Bound algorithm in which branches, or partitions, are subsets of discrete decision variables for waste treatment levels and the bounds are

Increased federal funding for municipal wastewater treatment; required states to develop water-quality standards; established Federal Water Pollution Control

Enclosed by this shorter discussion is the main body of the review dealing in turn with(!) identifiability and experimental design, (2) the generation of preliminary

1) The replacement of the phytoplankton biomass by oxygen concentration to express the photosynthetic oxygen production rate (equation 12) is a somewhat arbitrary

in which pS is the state estimation error covariance matrix, P is the parameter estimation error covariance matrix, and P P is a matrix representing error covariances between

The economic assumptions of the one season model will be used, for the most part, ,in the two season analysis. For the upstream user, the three piece linear benefit function given