Aptitude Regulatory News (APTD)

MICROGEN PLC

16 JANUARY 2012

BLOCK LISTING RETURN

Name of applicant: MICROGEN PLC

Name of scheme: MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME

Period of return: From: 1 JULY 2011 To: 31 DECEMBER 2011

Balance under scheme from previous returns:

MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME - 625,500 ORDINARY SHARES OF 5P EACH

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME - 112,291 ORDINARY SHARES OF 5P EACH

The amount by which the block scheme has

been increased, if the scheme has been

increased since the date of the last return: N/A

Number of securities issued/allotted under

scheme during period:

MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME - 172,500 ORDINARY SHARES OF 5P EACH

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME - 0 ORDINARY SHARES OF 5P EACH

Balance under scheme not yet issued/allotted

at end of period

MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME - 453,000 ORDINARY SHARES OF 5P EACH

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME - 112,291 ORDINARY SHARES OF 5P EACH

Number and class of securities originally

listed and the date of admission

MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME - 800,000 ORDINARY SHARES OF 5P EACH

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME - 200,000 ORDINARY SHARES OF 5P EACH

15 APRIL 2005

MICROGEN PLC 1997 AND 1999 EXECUTIVE SHARE OPTION SCHEME - 745,000 ORDINARY SHARES OF 5P EACH

MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME - 30,000 ORDINARY SHARES OF 5P EACH

27 JUNE 2008

Total number of securities in issue at the end

of the period

81,395,677 ORDINARY SHARES OF 5P EACH

The remaining securities listed under the MICROGEN PLC 1996 SAVINGS RELATED SHARE OPTION SCHEME have now expired and the scheme will no longer be referred to in subsequent returns.

Name of contact: ANJUM SIDDIQI, COMPANY SECRETARY

Address of contact: OLD CHANGE HOUSE, 128 QUEEN VICTORIA STREET, LONDON, EC4V 4BJ

Telephone number of contact: 020 7496 8100

www.microgen.com