population, for this particular sample, Is distributed over a wide variety 

 of genera with no single genus predominating. The major genera were 

 Arthrobacter , Bacillus , Gaf fkya , Moraxella , Sarcina , Staphylococcus 

 epidermus and Rhodotorula totally representing 64% of the population. 

 Most of the organisms, 52%, were associated with the first two stages 

 which retains particles greater than 5.5 . Arthrobacter , and Bacillus 

 are somewhat evenly distributed over the six stages while Moraxella , 

 Gaf fkya , Sarcina and Staphylococcus are predominantly found on the first 

 stage. The latter three genera are also associated with human skin and 

 may have originated from that source. One P^. aeruginosa colony was 

 isolated on stage three but no Staph , aureus was recovered. 



The population distribution for the crew-bridge compartment on day 13- 

 TSA is presented on Table 2. The major genera were Acinetobacter , 

 Arthrobacter , Gaf fkya , Moraxella and Sarcina totally representing 56% of 

 the population. Again, most of the organisms, 65%, were associated with 

 the first two stages while Gaf fkya and Sarcina were predominantly found 

 on the first two stages, as on day 2. One Staphylococcus aureus colony 

 was isolated from stage 1 but no Pseudomonas aeruginosa was recovered. 



In comparing the two days, 2 and 13, to determine what redistribution 

 had occurred it is seen that Acinetobacter has increased from 2% to 9% 

 of the organisms, Arthrobacter remained stable. Bacillus decreased but 

 remained evenly distributed, Gaf fkya and Morazella almost doubled, Staph . 

 epidermus decreased and the yeasts dropped considerately. Aeromonas , 

 Vibrio and a few other genera were not recovered on day 13 while Kurthia 

 increased to 5% of the population. On day two, 27 different genera or 

 groups of organisms were recovered with only 20 on day 13. This may 

 represent a slight simplification in the air flora. On day 13, 11 genera 

 were not recovered which had previously been recovered (albeit at low 

 levels) while four new genera were recovered. There was no redistribu- 

 tion of the genera within the six stages, those which were evenly dis- 

 tributed remained so (i.e. Bacillus ) and those associated with the larger 

 particles maintained that distribution (i.e. Gaf fkya ) . 



In grouping the organisms according to morphological and biochemical 

 similarities (Table 3) comparisons can be seen more readily, Table 4. 

 Some genera appear in more than one group, as Sarcina which is included 

 in the pigmented, fermentative and Gram-positive group. The pigmented, 

 Alcaligenes-Achromobacter , and Gram-positive rod groups increased with 

 some internal rearrangement while all those in the Gram-positive cocci 

 group increased, more notably Gaf fkya . Pseudomonas , the fermentative 

 group and the Gram-positive rods and yeasts group decreased. 



The distribution of organisms on the 2216 medium for day two in the crew- 

 bridge compartment reveals 17 different genera represented with a pre- 

 dominence in the Acinetobacter , Arthrobacter , Gaf fkya , Moraxella and 

 Sarcina genera. The groups differed from those on TSA for the same day 

 (Table 4) with most of the organisms in the Alcaligenes-Achromobacter 

 group . 



IX-43 



