Hydro Microbiology Overview

Hydro Microbiology

• Branch of science studying water and microorganisms within.
• Fresh water makes up 3%.
• Saltwater makes up 97%.

Potable vs. Non-Potable Water

• Potable water is clear, odorless, and tasteless.
• Non-potable water is contaminated and isn't safe to drink.
• Contamination can include physical factors like turbidity/color changes from floods, or chemical factors from industrial waste, agricultural runoff, acid rain, or nuclear residue.

Biological Analysis

• Microorganisms like bacteria and viruses from sewage or industrial drainage can cause pathogenicity.

Chemical Analysis

• Dissolved oxygen (DO) is the amount of oxygen dissolved in aquatic ecosystems.
• Measured using direct methods like oxygen meters or titration methods.

Dissolved Oxygen (DO) by Titration Method

• Take a known water volume (50ml-100ml).
• Add fixing solution.
• Add indicator (K2Cr2O7; KOH)
• Titrate against 0.025N sodium thiosulfate until the color changes.
• Calculate the DO using the formula.
• Repeat the titration three times.

Biological Oxygen Demand (BOD)

• Amount of dissolved oxygen used by aerobic microorganisms to break down organic matter over time.
• Sources of organic matter include industrial waste, dead organisms, and other materials.
• Water quality is measured based on BOD results with respect to various ranges.

Procedures to Determine BOD

• Collect two water samples from same source.
• Immediately measure initial Dissolved Oxygen (DO) in one sample via titration.
• Incubate the second sample at 28-30°C for 5 days.
• Measure the final dissolved oxygen (DO) of this second incubated sample by titration.
• Calculate the BOD using the formula: BOD = Initial DO - Final DO.

Hints for Section

• Temperature (28-30°C) is suitable for microbial growth due to enzyme activity.
• Aquatic organisms rely on dissolved oxygen for their respiration.
• Diffusion and wave movements affect oxygen distribution in water systems.

Biological/Bacteriological Examination of Water Samples

• Aim: Recognize potable versus non-potable water by checking for bacterial growth.
• Factors affecting microbes in water include toxins, heavy metals, physical, and chemical environmental factors.
• Examples of water pollutants are sewage waste, pathogenic bacteria, Salmonella, etc.

Pathogenic Bacteria

• Changes from non-pathogenic to pathogenic can cause serious illness.
• Detection is expensive and has a short survival timeframe.
• Classification differences include Gram staining, morphology, and whether they are gram postive (+ve) or gram negative (-ve).

Presumptive, Confirmed, and Completed Tests

• Identify E.coli in water samples.
• Presumptive (qualitative) tests involve looking for color changes and gas production.
• Confirmed tests use selective media (like Eosin Methylene Blue (EMB) or MacConkey) to identify specific bacteria.
• Completed tests (like Gram stain) confirm morphology to ensure the bacteria is properly identified.

Water Sample Preservation

• Using slants increases surface area for microbial growth and reduces contamination.
• Slants help maintain the viability of bacteria for long periods.

Quantitative Analysis of Water Samples

• Water sample testing for microorganisms.
• Counting microbes.
• Determining if water is potable or not using a treatment efficiency method.

Most Probable Number (MPN) Method

• Counting method used to determine the number of microbes in a water sample.
• Depends on the results of presumptive tests and requires multiple tubes for analysis.
• Various calculations are needed based on the results in the index table.

Membrane Filter Technique (MFT)

• Method to determine the number of microorganisms/bacteria in a water sample.
• Selective media and sterilization steps are involved to isolate desired findings.

Advantages of MFT

• Reduces time and equipment requirements for large-volume water sample analyses.
• Permanently records analytical results.
• Identifies the presence or absence of E.coli in a water sample after 24 hours of incubation.
• Isolates and quantifies coliform bacteria.
• Efficient and acceptable method.

IMViC Tests

• Group of tests differentiates genera of coliform bacteria.
• Indole Production, Methyl Red, Vogues Proskaeur, and Citrate are included.
• Indicates the bacterial species based on results (acidic or basic).

Citrate Test

• Citrate test identifies if bacteria can use citrate as a carbon source.
• Note: Citrate medium turns blue when bacteria grow on it and use citrate because the pH will increase.
• Procedure to conduct the citrate agar media test.
• Observations for bacterial growth (positive result = +ve).
• Observations for bacterial non-growth (negative result = -ve).

Explore the fascinating field of hydro microbiology, focusing on the interaction between water and microorganisms. Learn about the critical differences between potable and non-potable water, and the analytical methods used to assess water quality, including biological and chemical analyses. This quiz will test your knowledge on important concepts like dissolved oxygen and its measurement.