624 
Diastatic  Ferment  of  Bacteria. 
Am.  Jour.  Pharm_ 
Dec,  1883. 
bacteria.  The  result  of  further  precise  experiments,  undertaken  to 
decide  this  point,  led  to  the  conclusion  that  bacteria  are  capable  of 
drawing  their  supply  of  carbon  from  starch,  and  that  the  appearances 
of  solution  or  corrosion  exhibited  by  the  solid  starch  granules  are 
identical  with  those  caused  by  the  action  of  diastase  or  saliva. 
The  method  used  by  the  author  was  as  follows :  To  about  20  or  25 
cc.  a  mixture  of  inorganic  salts  (sodium  chloride,  magnesium  sulphate, 
potassium  nitrate,  and  acid  ammonium  phosphate)  in  equal  propor- 
tions was  added  to  the  extent  of  1  per  cent.  The  same  quantity  of 
solid  wheat-starch  was  then  added,  and  the  liquid  then  inoculated  with 
one  or  two  drops  of  a  strongly  bacterial  solution,  shaken,  corked,  and 
allowed  to  remain  in  a  room  at  a  temperature  of  18  to  22°.  [^Bacte- 
rium  termo  was  the  predominating  organism  in  the  inoculating  fluids 
employed.]  In  from  5  to  7  days,  the  first  signs  of  commencing  corro- 
sion of  the  starch  grains  become  visible,  the  larger  grains  being  the 
earliest  attacked,  and  much  later,  when  these  have  almost  completely 
disappeared,  the  lesser  granules  are  attacked. 
In  a  second  series  of  experiments  soluble  starch  was  substituted  for 
the  solid  form,  the  progress  of  the  reaction  being  watched  by  the  aid 
of  iodine.  Samples  taken  from  time  to  time  exhibited  at  first  the- 
blue  color,  then  violet  or  dark  red,  passing  to  wine-red,  and,  finally,, 
when  the  starch  had  disappeared,  underwent  no  change. 
As  Baranetzky  has  shown,  the  starch  granules  of  different  kinds  are 
acted  on  with  very  unequal  rapidity  by  the  diastatic  ferments  of  plant 
juices,  the  strongest  ferment  of  all — malt  diastase — being  well  known 
to  have  no  perceptible  influence,  even  after  long  exposure,  on  solid 
potato-starch  granules,  whilst  wheat  and  buckwheat  are  dissolved  with 
facility. 
Experiments  were  made  with  a  view  to  ascertain  whether  the  action- 
of  bacteria  on  starch  was  analogous ;  in  these  wheat-starch  grains  are 
shown  to  be  by  far  the  most  readily  attacked  by  bacteria — in  several 
instances  having  even  completely  disappeared  before  other  sorts  of 
starch  were  attacked.  Differences  were  also  noticed  in  regard  to  the 
times  when  palm-starch,  canna-starch,  turmeric-starch,  and  iris-starch 
were  attacked,  their  degree  of  resistance  being  in  the  order  given. 
Potato-starch  alone  resisted  attack.  When  wheat-starch  in  the  solid 
state  was  mixed  with  starch  solution  or  with  starch-paste,  the  solution 
became  entirely  (and  the  paste  in  greater  part)  changed  before  the  solid 
granules  were  attacked. 
