As jyotsna has addressed the first part of ur question I am answering the second part with an example.

In May 2011, a virtually unknown strain of E. coli, now known as O104:H4, made worldwide headlines when an outbreak in Germany sickened approximately 4,000 people and killed 50. This event quickly became the deadliest food borne illness outbreak in history. It was related with some fresh vegetable imported in Germany, the source and the vegetable, at that time was unknown. Using NXG, whole genome of E.coli (O104:H4) was mapped within days – a feat that would have taken months if the outbreak had happened a decade earlier. This resulted in comparing and understanding the gene responsible for parthenogenesis in this Ecoli strain. Also the source of this pathogen was traced within few weeks.There are lot of more information on net which will give you detail information about this particular event and many more such study.

New sequencing techniques evolved after Sanger's sequencing is known as next generation sequencing. 454-Roche pyrosequencing, Illumina solexa are the NG platforms used vividly these days. This platforms helps to microbial diversity study(metagenomic study), functional gene gene diversity of environmental sample. 

As jyotsna has addressed the first part of ur question I am answering the second part with an example.

In May 2011, a virtually unknown strain of E. coli, now known as O104:H4, made worldwide headlines when an outbreak in Germany sickened approximately 4,000 people and killed 50. This event quickly became the deadliest food borne illness outbreak in history. It was related with some fresh vegetable imported in Germany, the source and the vegetable, at that time was unknown. Using NXG, whole genome of E.coli (O104:H4) was mapped within days – a feat that would have taken months if the outbreak had happened a decade earlier. This resulted in comparing and understanding the gene responsible for parthenogenesis in this Ecoli strain. Also the source of this pathogen was traced within few weeks.There are lot of more information on net which will give you detail information about this particular event and many more such study.