A biological culture unit , comprising: a chamber body having a top surface and a bottom surface , the chamber body having defined therein a growth chamber having an access opening at the top surface and an aliquot chamber having an access opening at the top surface and a first fluid path extending from the growth chamber to the top surface and a second fluid path extending from the aliquot chamber to the top surface; a valve plate disposed on the top surface of the chamber body and rotatably connected with the chamber body to rotate about a rotation axis relative to the chamber body, the valve plate including a growth chamber access port , an aliquot chamber access port , a transfer actuator , and a third fluid path , the valve plate being rotatable about the rotation axis into a plurality of selectable positions including: a loading position in which the growth chamber access port is aligned with the access opening of the growth chamber and the third fluid path is not aligned to connect the first and second fluid paths; a transfer position in which the third fluid path is aligned to connect the first and second fluid paths and the transfer actuator is aligned with one of the access opening of the growth chamber and the access opening of the aliquot chamber; and an extraction position in which the aliquot chamber access port is aligned with the access opening of the aliquot chamber and the third fluid path is not aligned to connect the first and second fluid paths. a chamber body having a top surface and a bottom surface , the chamber body having defined therein a growth chamber having an access opening at the top surface and an aliquot chamber having an access opening at the top surface and a first fluid path extending from the growth chamber to the top surface and a second fluid path extending from the aliquot chamber to the top surface; a valve plate disposed on the top surface of the chamber body and rotatably connected with the chamber body to rotate about a rotation axis relative to the chamber body, the valve plate including a growth chamber access port , an aliquot chamber access port , a transfer actuator , and a third fluid path , the valve plate being rotatable about the rotation axis into a plurality of selectable positions including: a loading position in which the growth chamber access port is aligned with the access opening of the growth chamber and the third fluid path is not aligned to connect the first and second fluid paths; a transfer position in which the third fluid path is aligned to connect the first and second fluid paths and the transfer actuator is aligned with one of the access opening of the growth chamber and the access opening of the aliquot chamber; and an extraction position in which the aliquot chamber access port is aligned with the access opening of the aliquot chamber and the third fluid path is not aligned to connect the first and second fluid paths. a loading position in which the growth chamber access port is aligned with the access opening of the growth chamber and the third fluid path is not aligned to connect the first and second fluid paths; a transfer position in which the third fluid path is aligned to connect the first and second fluid paths and the transfer actuator is aligned with one of the access opening of the growth chamber and the access opening of the aliquot chamber; and an extraction position in which the aliquot chamber access port is aligned with the access opening of the aliquot chamber and the third fluid path is not aligned to connect the first and second fluid paths. <EOS>