﻿550 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1943 
  

  

  therefrom 
  an 
  organism 
  capable 
  of 
  attacking 
  Gram-positive 
  cocci. 
  1 
  

   The 
  technic 
  adopted 
  was 
  to 
  add, 
  from 
  time 
  to 
  time, 
  suspensions 
  of 
  

   living 
  streptococci 
  and 
  staphylococci 
  to 
  soil 
  in 
  the 
  hope 
  of 
  provoking 
  

   the 
  development 
  of 
  a 
  microbial 
  flora 
  able 
  to 
  utilize 
  these 
  cells. 
  In 
  1939, 
  

   after 
  a 
  period 
  of 
  2 
  years, 
  he 
  was 
  able 
  to 
  announce 
  the 
  success 
  of 
  the 
  

   experiment. 
  There 
  was 
  isolated 
  from 
  the 
  soil 
  a 
  bacterium, 
  identified 
  

   as 
  Bacillus 
  brevis, 
  which 
  brought 
  about 
  the 
  lysis 
  of 
  living 
  staphylo- 
  

   cocci, 
  streptococci, 
  and 
  pneumococci. 
  A 
  short 
  time 
  later 
  Hoogerheide, 
  

   who 
  had 
  been 
  working 
  independently 
  at 
  the 
  Franklin 
  Institute, 
  also 
  

   reported 
  the 
  isolation 
  of 
  several 
  strains 
  of 
  soil 
  bacilli 
  which 
  pro- 
  

   duced 
  antibacterial 
  substances. 
  Other 
  species, 
  endowed 
  with 
  the 
  same 
  

   type 
  of 
  antagonistic 
  activity, 
  have 
  been 
  obtained 
  also 
  from 
  sewage 
  

   and 
  from 
  cheese. 
  

  

  Tyrothricin, 
  gramicidin, 
  and 
  tyrocidine. 
  — 
  It 
  was 
  soon 
  found 
  that 
  

   the 
  lytic 
  properties 
  were 
  exhibited 
  not 
  only 
  by 
  the 
  living 
  Bacillus 
  

   brevis, 
  but 
  also 
  by 
  cell-free 
  solutions 
  obtained 
  from 
  old 
  cultures 
  in 
  

   which 
  self-digestion, 
  or 
  autolysis, 
  of 
  the 
  bacteria 
  had 
  taken 
  place. 
  

   From 
  such 
  solutions 
  there 
  have 
  been 
  obtained 
  several 
  active 
  fractions 
  

   which 
  differ 
  in 
  chemical 
  composition 
  and 
  in 
  biological 
  properties. 
  

   Apparently 
  these 
  various 
  substances 
  are 
  derived, 
  through 
  the 
  proc- 
  

   esses 
  of 
  autolysis 
  and 
  the 
  subsequent 
  manipulations 
  of 
  extraction, 
  

   from 
  a 
  single 
  parent 
  substance 
  originally 
  present 
  in 
  the 
  bacterial 
  

   cell. 
  On 
  acidification 
  of 
  the 
  culture 
  fluid 
  there 
  is 
  obtained 
  a 
  protein 
  

   precipitate 
  from 
  which 
  a 
  protein-free 
  active 
  substance 
  can 
  be 
  ex- 
  

   tracted 
  with 
  alcohol 
  and 
  precipitated 
  with 
  salt 
  solution. 
  The 
  material 
  

   obtained 
  in 
  this 
  manner 
  has 
  been 
  designated 
  "tyrothricin" 
  afteir 
  

   Tyrothrix, 
  the 
  old 
  generic 
  name 
  of 
  a 
  group 
  of 
  bacteria 
  early 
  recog- 
  

   nized 
  as 
  having 
  antagonistic 
  properties. 
  About 
  half 
  a 
  gram 
  of 
  tyro- 
  

   thricin 
  can 
  be 
  prepared 
  from 
  a 
  liter 
  of 
  bacterial 
  culture. 
  Tyrothricin 
  

   has 
  been 
  further 
  separated 
  into 
  two 
  active 
  components, 
  named 
  "grami- 
  

   cidin" 
  and 
  "tyrocidine," 
  which 
  account 
  for 
  approximately 
  20 
  and 
  50 
  

   percent, 
  respectively, 
  of 
  the 
  parent 
  material. 
  

  

  Both 
  gramicidin 
  and 
  tyrocidine 
  have 
  beert 
  isolated 
  in 
  pure 
  crystal- 
  

   line 
  state 
  and 
  considerable 
  information 
  concerning 
  their 
  chemical 
  

   properties 
  has 
  been 
  obtained. 
  Both 
  compounds 
  are 
  complex 
  poly- 
  

  

  1 
  In 
  the 
  staining 
  technic 
  devised 
  by 
  the 
  Danish 
  bacteriologist 
  Gram, 
  the 
  bacteria 
  are 
  

   treated 
  successively 
  with 
  a 
  dye, 
  such 
  as 
  gentian 
  violet, 
  with 
  iodine, 
  and 
  with 
  alcohol. 
  

   Those 
  which 
  are 
  decolorized 
  by 
  the 
  alcohol 
  are 
  termed 
  Gram-negative, 
  whereas 
  those 
  which 
  

   retain 
  the 
  dye 
  are 
  Gram-positive. 
  Although 
  the 
  Gram 
  stain 
  was 
  introduced 
  as 
  a 
  purely 
  

   empirical 
  procedure, 
  it 
  has 
  been 
  found 
  to 
  differentiate 
  bacterial 
  species 
  into 
  two 
  fairly 
  

   sharply 
  defined 
  groups 
  which 
  differ 
  also 
  in 
  numerous 
  structural 
  and 
  physiological 
  character- 
  

   istics. 
  The 
  reason 
  for 
  the 
  difference 
  in 
  staining 
  properties 
  is 
  not 
  entirely 
  clear 
  but 
  presum- 
  

   ably 
  is 
  related 
  to 
  the 
  properties 
  of 
  the 
  cell 
  wall. 
  

  

  Of 
  the 
  common 
  disease-producing 
  cocci, 
  the 
  streptococci, 
  staphylococci, 
  and 
  pneumococci 
  

   are 
  Gram-positive, 
  whereas 
  the 
  gonococci 
  and 
  meningococci 
  are 
  Gram-negative. 
  Among 
  the 
  

   Gram-positive 
  bacilli 
  are 
  the 
  causal 
  organisms 
  of 
  diphtheria, 
  gas 
  gangrene, 
  tetanus, 
  tuber- 
  

   culosis, 
  leprosy, 
  and 
  anthrax 
  ; 
  Gram-negative 
  bacilli 
  include 
  the 
  agents 
  of 
  typhoid 
  and 
  para- 
  

   typhoid 
  fevers, 
  bacillary 
  dysentery, 
  bubonic 
  plague, 
  and 
  undulant 
  fever. 
  

  

  