Examination of Bacterial Content of Sea Water

Topics: Bacteria, Microbiology, Water Pages: 6 (1418 words) Published: March 24, 2010
Project Title: Examination of bacterial content of sea water samples from selected sites in South East England Introduction Over the past few years coastal beaches across the UK has seen lavished with recognition for their cleanliness, by sections of the media and various organisarions. Majority of these beaches have been awarded the Blue flag award in recognition for meeting set criteria on various standard including cleanliness, water quality, environmental management and environmental education and information programme; an award ran by independent non-profit organisation Foundation for Environmental Education (FEE) and with similar programme ran by The marine conservation society (MCS). The general perception is that this beaches clean due to the reduce numbers of household litters presents, giving the impression that the litter level are the determinant of the cleanliness of the water.

This study intends to examine:

The bacteria population of samples obtained from several site across south east coast of England. Identify species of Gram Negative (-) & (+) of each sample. identify any faecal coliform bacteria which might suggest water contamination.

These indicator organisms are used for indication of water contaminant by human and other warm-blooded animals (APHA 1992). Several sample will be obtained from beach that are participant in some form of recognised sanitary programme and have meet set criteria by a recognised monitoring body. While several more sample will be obtained from location not participating in any such sanitary programmes. This will ensure an even sample distribution of bacterial population and data comparison.

Various bacteriological techniques will then be employed to help identify any present bacteria species.


Of the four samples; the bacteria population count would be lower in samples obtained from location awarded the “blue flag” award.

Material, Equipment and Method

Petri dish
70% Alcohol Bleach
Sterile water/ saline solIodine solution
R2A & R3A AgarMacConkey Agar
Masking Tape Acetone Alcohol
Safranine Sterile swab
Crystal violet dyeMicroscopic oil Micropipette Tips (20- 2000 µl, 200-1000 µl, 1-5mL)Inoculating loops & wire Micro-slideMarking pen
Pipette PasteurSterile forceps
Mannitol salt agarBlood agar
Filter paperSample containers
Durham’s (fermentation tube) tubeTDA
Ringer solution (Quarter strength)Hydrogen peroxide
API Gram (+)(-)selective biochemical test kits/ API 20EIND reagent TMPD or DMPD (Redox indicators)
James reagent

Equipment :

Bunsen burner
Stop clock
Micropipette (20- 2000 µl, 200-1000 µl, 1-5mL)
Glass Rod spreader
Laboratory coat
Rubber glove
Light Microscope
Staining rack
Coulter Counter
Test tube, bottles, caps & stoppers
Discard jars
disinfectant pot
Beaker flask

Experimental Methodologies
The bacteria population first needs to be analysis. The water sample will be transferred to the laboratory in a cold chain under aseptic conditions to minimise the risk of contamination

The sample under investigation would certainly contain mixtures of various organisms. In order to assess the bacterial flora population of the samples, it is essential to use selective and non- selective media because no one medium or temperature will support all present organisms. This will provide suitable favourable growth environment for the various group of organisms.

Direct Count Method

The bacteria population of an unknown mixture is investigated using the direct count method. First; the four original samples will be diluted to 10-¹ to 10-³ in peptone / deionised water and 0.1 mL of these dilutions will then be streaked in triplicate with the spread plate technique onto the selective (MacConkey, Blood agar,...

References: APHA (1992) Standard Methods for the Examination of Water and Wastewater, 15th edn. New York: Water Pollution Control Federation
Bergey, David H.; John G. Holt; Noel R. Krieg; Peter H.A. Sneath (1994). Bergey 's Manual of Determinative Bacteriology (9th ed.). Lippincott Williams & Wilkins
Madigan, MT; Martinko J, Parker J (2004). Brock Biology of Microorganisms (10th ed.). Lippincott Williams & Wilkins.
Reasoner, D.J. & Geldreich E.E. (1995). A new medium for the enumeration and subculture of bacteria from portable water. Applied and Environmental Microbiology.49, 1-7.
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