during a short investigative period in the same water body both in the marine and fresh
water aquatic environments. However, several reports have been published concerning
the distribution of the concentration of B group vitamins. The present paper appears to be
the first field study of the continual fluctuations in the concentration of B group vitamins
for a successive 30 hour period in an in situ closed system.
MATERIALS AND METHODS
Water samples were collected every 6 hours over a 30 hour period from three depths (5 m,
thermocline and 30 m) at a station located in the pelagic zone of the main basin of Lake
Biwa. 21 subsamples from three layers were enclosed into glass bottles and incubated in
situ for 6 hours at the same depth of the station. The incubation of the water samples was
carried out at every successive sampling time during the investigative period. Immediately
after sampling, the water samples collected and the incubated samples were carried back
to the laboratory and used for the assay of thiamine, biotine and vitamin B
12
by the
microbiological method discribed in the previous paper (Kurata A. et al., 1976). For the
assay of B group vitamins, water samples were concentrated by approximately 50-fold, by
evaporation under reduced pressure at 40°C. The concentrations of thiamine, biotin and
vitamin B12 were determined microbiologically, using Lactobacillus fermenti ATCC
9338, L. arabinosus ATCC 8014 and L. leichmannii ATCC 7830, respectively. Heterotrophic bacteria were isolated from the water and Egeria densa using ZoBell 2216 F medium
(ZoBell 2216 medium prepared with distilled water) and examined for the production of
thiamine, biotin and vitamin B12.
RESULTS AND DISCUSSION
Successive variations in the concentration of thiamine, biotin and vitamin B12 in waters
from 5 m, thermocline and 30 m deep layers were examined over 30 hours at the
designated station. Thiamine data are shown as an example in Figure 1. The concentrations of the three kinds of vitamins showed a greater range in the 5 m deep layer than in the
30 m deep layer. Generally, the concentrations of vitamins increased gradually from the
Figure 1 : Fluctuations of the concentration of thiamine for 30 hours in a 5
m deep layer (O—), in a thermocline (A—) and in a 30 m deep layer
(□...).
170
water aquatic environments. However, several reports have been published concerning
the distribution of the concentration of B group vitamins. The present paper appears to be
the first field study of the continual fluctuations in the concentration of B group vitamins
for a successive 30 hour period in an in situ closed system.
MATERIALS AND METHODS
Water samples were collected every 6 hours over a 30 hour period from three depths (5 m,
thermocline and 30 m) at a station located in the pelagic zone of the main basin of Lake
Biwa. 21 subsamples from three layers were enclosed into glass bottles and incubated in
situ for 6 hours at the same depth of the station. The incubation of the water samples was
carried out at every successive sampling time during the investigative period. Immediately
after sampling, the water samples collected and the incubated samples were carried back
to the laboratory and used for the assay of thiamine, biotine and vitamin B
12
by the
microbiological method discribed in the previous paper (Kurata A. et al., 1976). For the
assay of B group vitamins, water samples were concentrated by approximately 50-fold, by
evaporation under reduced pressure at 40°C. The concentrations of thiamine, biotin and
vitamin B12 were determined microbiologically, using Lactobacillus fermenti ATCC
9338, L. arabinosus ATCC 8014 and L. leichmannii ATCC 7830, respectively. Heterotrophic bacteria were isolated from the water and Egeria densa using ZoBell 2216 F medium
(ZoBell 2216 medium prepared with distilled water) and examined for the production of
thiamine, biotin and vitamin B12.
RESULTS AND DISCUSSION
Successive variations in the concentration of thiamine, biotin and vitamin B12 in waters
from 5 m, thermocline and 30 m deep layers were examined over 30 hours at the
designated station. Thiamine data are shown as an example in Figure 1. The concentrations of the three kinds of vitamins showed a greater range in the 5 m deep layer than in the
30 m deep layer. Generally, the concentrations of vitamins increased gradually from the
Figure 1 : Fluctuations of the concentration of thiamine for 30 hours in a 5
m deep layer (O—), in a thermocline (A—) and in a 30 m deep layer
(□...).
170