The effects have been investigated of closures and vessels on light intensities inside closed vessels. Four kinds of closures (aluminum foil cap (CA), translucent polypropylene formed cap (CP), silicon foam rubber plug (PS) and transparent polycarbonate formed lid (LP)) and three kinds of vessels (47ml glass flat bottom test tube, 132ml glass Erlenmeyer flask and 370ml polycarbonate box type vessel) were used. One straight fluorescent tube (cool white) was employed as a light source. Light intensities were measured using an illuminometer with a small photoreceptor. The measured illuminance [lx] was converted into the photon flux of 400-700nm wave lengths [μmol·m-2·s-1]. The results can be summarized as follows:
(1) The percentage of the photon flux reduction due to the closures to the photon flux on the shelf surface was 41% for CA, 8% for CP, and 49% for PS in case the test tubes were used as a vessel, and was 17% for CA and 24% for PS in case the flasks were used as a vessel.
(2) The percentage of the photon flux reduction due to the test tubes including stainless wire frame stands, and the flasks, to the photon flux on the shelf surface was 36% and 7%, respectively.
(3) Mean photon flux inside the closed vessels was in the order:
CA-flask (45)>PS-flask(41)>LP-box type vessel (38)
>CP-test tube (33)>CA-test tube (14)>PS-test tube (9)
Values in the parentheses indicate the mean photon flux [μmol·m-2·s-1]. The mean photon flux on the shelf surface was 59 μmol·m-2·s-1.
(4) The photon flux inside each closed vessel was dependent on each position of the closed vessel on the culture shelf, and the distribution of the photon flux varied markedly with the closure-vessel combination.