Environmental Microbiology of Aquatic and Waste Systems

40 3 Aspects of the Molecular Biology of Microorganisms of Relevance to the Aquatic Environment

Southern blot. Microarrays have the following advan-
tages over other nucleic acid–based approaches:
(a) High throughput: Thousands of array elements
can be deposited on a very small surface area
enabling gene expression to be monitored at the
genomic level. Also, many components of a micro-
bial community can be monitored simultaneously
in a single experiment.
(b) High sensitivity: Small amounts of the target and
probe are restricted to a small area ensuring high
concentrations and very rapid reactions.
(c) Differential display: Different target samples can
be labeled with different fluorescent tags and then
hybridized to the same microarray, allowing the
simultaneous analysis of two or more biological
samples.

(d) Low background interference: Non-specific bind-

ing to the solid surface is very low resulting in easy

removal of organic and fluorescent compounds that

attach to microarrays during fabrication.

(e) Automation: Microarray technology is amena-

ble to automation making it ultimately cost-

effective when compared with other nucleic acid

technologies.

3.3.1 Applications of Microarray Technology

Microarray technology is still young but yet it has

found use in a few areas which have importance in

microbiology in general as well as in.

1

Preparation of the

micro array slide

Slideismade of

chemical-resistant

glasscoated with

poly(L-lysine) or

other cross-linking

chemical which

anchors the DNA

on to the glass.

2

mRNA of interest

prepared

AAA

TTT

cDNA

3

mRNA of interest

placed in specific

positions on slide

4

Probe labelled

with fluorescent

dye introduced

on slde

5

Slides scanned

for fluorescenc ie

for hybridiztion

Fluorescent

probe

Fluorescent

probe

DNA of interest

Control (No hybridization with probe)

(Hybridization with probe)

Spotting of

mRNA

and of the

probe done

robotically

Spotting of

mRNA

and of the

probe done

robotically

Fig. 3.5 Schematic representation of the cDNA microarray procedure