A biological culture unit comprises a chamber body and a valve plate. The chamber body has defined therein a growth chamber and an aliquot chamber. The valve plate is disposed on the top surface of the chamber body and is movable to define selectable configurations of the biological culture unit for: (1) loading the growth chamber; (3) transferring an aliquot from the growth chamber to the aliquot chamber via a path defined within the biological culture unit in the transfer position; and (4) extracting the aliquot from the aliquot chamber. The selectable positions may further include (2) a growth position, and (5) a termination position for putting a termination agent into the growth and aliquot chambers. The valve plate may further include a neutralizer port that is aligned with the aliquot chamber in the loading position, for loading a neutralizing agent into the aliquot chamber.