The main purpose of the last line of the passage is to signal the reader that steps will follow.
In the first part of the passage, the author is giving some <em>background information</em> about the topic, which functions as an introduction to develop the main topic. The last sentence serves <em>to trigger</em> what the passage is actually concerned in, that is, the different ways in which contamination by this bacterium can be avoided. Thus, what the reader is expecting after the last line are some steps to follow.
This is a rather subjective question, and it really depends on your personal opinions about the topic. In my eyes, yes, justice and forgiveness can go hand in hand. Let's take an example of an offender who committed a particular crime.
He or she will be prosecuted for what they did, and thus justice will be served. However, after they've endured their punishment, they might become law-abiding citizens again, and this is where forgiveness takes place - they can be forgiven for their evil deeds and allowed back into the society (although, this depends on the crime they've committed).
