Chapter 1, Problem 1E.1RQ

(a)

Summary Introduction

To explain: The purpose of flaming inoculating instrument prior to and after each inoculation.

Introduction: Subculture technique is used to carry on the growth of the bacteria. During subculture, a bacterium is transferred from the initial growth medium to another medium, which is useful for microbial tests and also in producing bulk stock cultures of the desired bacterium.

Explanation of Solution

The inoculating instrument used for inoculation is maybe of inoculation loop or inoculation needle. These instruments are made up of tungsten material that heats up and cools down quickly. The purpose of flaming the instrument prior to and after each inoculation is to destroy or reduce any potential microbes that can contaminate the culture.

(b)

Summary Introduction

To explain: The purpose of holding the test tube caps in the hand.

Introduction: Subculture technique is used to carry on the growth of the bacteria. During the subculture, a bacterium is transferred from the initial growth medium to another medium, which is useful for microbial tests and also in producing bulk stock cultures of the desired bacterium.

Explanation of Solution

The microbes are transferred from one stock medium to another medium in the subculture. During the procedure, two test tubes are held in a V shape to avoid contact with one another. The cap from the stock is removed by the little finger and the cap from another test is removed in-between the index and middle finger. This type of procedure is followed to avoid placing of the caps in the bench of the laminar airflow chamber that might contaminate the place as well cross-contaminate the inoculating medium.

(c)

Summary Introduction

To explain: The importance of cooling the inoculating instrument prior to obtaining the inoculum.

Introduction: Subculture technique is used to carry on the growth of the bacteria. During the subculture, a bacterium is transferred from the initial growth medium to another medium, which is useful for microbial tests and also in producing bulk stock cultures of the desired bacterium.

Explanation of Solution

The inoculating instrument used for inoculation is maybe of inoculation loop or inoculation needle. These instruments are made up of tungsten material that heats up and cools down quickly. The cooling of the inoculating instrument is important before obtaining the inoculum. Hence, placing the instrument while it is red hot will result in the death of the microbes and no growth will be seen in the subculture.

(d)

Summary Introduction

To explain: The importance of flaming the neck of the tubes immediately after uncapping and before recapping.

Introduction: Subculture technique is used to carry on the growth of the bacteria. During the subculture, a bacterium is transferred from the initial growth medium to another medium, which is useful for microbial tests and also in producing bulk stock cultures of the desired bacterium.

Explanation of Solution

The purpose of flaming the neck of the tubes before and capping and uncapping is to destroy any microbes present at the neck of the tubes. Moreover, it also reduces the chance of any contamination by aerosols or by touching the necks of the tubes.