Mar., 1923] WEIMER AND HARTER — PECTINASE PRODUCTION 
129 
amount of enzym was exuded into the substrate by reflexus at 40° and its 
action was determined, but the actual amount of mycelium produced was 
so small that its macerating power could not be measured. 
Table i. Average rate of maceration by the enzym exuded into the solution upon which the 
different species of Rhizopus grew at various temperatures , as well as by 
that retained by the mycelium* 
In Solution 
R. 
reflexus 
R. 
delemar 
R. 
oryzae 
R. 
chinen¬ 
sis 
R. 
nodosus 
R. 
tritici 
R. 
micro¬ 
sporus 
R. 
maydis 
10 
4-7 
4-7 
4-9 
3-2 5 
4 
5-5 
2-75 
2.1 
2.15 
4-5 
2.05 
1.45 
1-3 
2 
2 
1.5 
5 
i-75 
1.25 
1-75 
1-25 
2-5 
3.25 
1.87 
2 
244- 
Temperature 
for Growth 
of Fungi 
(° C.) 
R . 
nigri¬ 
cans 
40. 
30 . 
20. 
9 • 
4.87 
484- 
In Mycelium 
40. 
8 
8 
8-24 
4 
4-5 
30. 
3 
5 
3.8 
6 
3.8 
2.5 
20. 
3 
3 
3-5 
6.5 
3 
2.5 
9. 
2-75 
2.5 
2.87 
2.67 
2-5 
3 
8 
24 
8-24 
24 
Figures indicate time in hours necessary to complete maceration. 
The table shows that the enzym content of the solution was least 
when the different species were grown at 40° C., the time required to macer¬ 
ate the disks varying from 3.25 hours to 10 hours. Reflexus, a low-tempera¬ 
ture form, made a very feeble growth at 40°. Under these conditions the 
total amount of pectinase produced by it was small in comparison with that 
secreted by the other species grown at the same temperature. On the 
other hand, the time required to macerate the disks was considerably 
shortened when the growth took place at 30°. This is particularly true of 
reflexus , which grew much better at the latter temperature. With respect 
to this temperature, it is interesting to note that chinensis, which, together 
with microsporus, was shown (1) not to be parasitic on sweet potatoes, 
required a much longer time to macerate the tissue than any of the other 
species. Both species, however, were shown elsewhere (2) to produce a 
pectinase when grown at 30° which would disintegrate raw sweet-potato 
tissue. At 20° all the species made a good growth and exuded a considerable 
quantity of enzym into the substrate. The time required for the enzym to 
complete maceration was less when the fungus was grown at this temperature 
than when it was grown at 30°, with one exception, chinensis, although the 
difference in time here is not great. Both chinensis and nigricans required 
two to four times longer than any of the other species completely to dissolve 
out the middle lamellae of the disks. At 9 0 several of the fungi made no 
growth. This is particularly true of the high-, and of some of the inter¬ 
mediate-temperature forms. The enzym exuded into the solution by 
microsporus and nigricans, which made a slight growth at 9 0 , required 24 
