Dr. John Spizizen and 
Dr. Donald Hel inski 
July 18, 1978 
Page Two 
adopts an ultra conservative point of view. Espousing the ultra conservative 
point of view, one could hold that E_. col i chromosomal genes might not be expressed 
in £_. aeruginosa and thus cloning of E_. col i DMA into various strains of P_. aeru- 
ginosa should not be permitted outside the Guidelines until such had been demon- 
strated by experimental data. On the other hand, with a somewhat liberal point of 
view one can argue that the reciprocal could also occur naturally. 
List 2. Citrobacter freundii into Escherichia coli . The same considerations as 
enumerated above can be cited. 
However, in the absence of data, one could not clone Citrobacter freundii DNA 
into Pseudomonas aeruginosa or vice versa outside of the Guidelines even though 
both C_. freundi i and P_. aeruginosa can exchange with E_. col i . 
Thus based on a conservative approach, *one would have a variety of groupings 
depending upon published data with the possibility that one could permit reciprocal 
cloning even though the data were only unidirectional from one donor to one 
recipient, a somewhat more liberal stance. 
A second factor to consider in the conservative approach deals with how much 
credence one wishes to place on taxonomic relationships using whatever taxonomy 
( i . e . , Bergy's Manual) one chooses. In this regard, Escherichia coli as one species 
has almost as much diversity as the entire genus Salmonella and the genus Pseudo- 
monas has as much or more diversity than all the species in the family Entero- 
bacteriaceae . Thus to include all Pseudomonas species on one list in the 
absence of data is contrary to the conservative approach. In other words, there 
is data to show that P_. aeruginosa , P_. putida , P/ glycinea and a few other species 
do indeed have the capability of transmitting plasmids and/or chromosomal DNA to 
E_. col i K-12 but such data is not available for the vast majority of Pseudomonas 
species. Thus using a conservative approach, one could not list all species of 
Pseudomonas or for that matter all species of any of the genera listed in the 
present Appendix A since the data does not exist in the literature. 
The Liberal Position 
Include all those species and/or genera if any type of gene transfer occurs 
(transformation, transduction and/or conjugation including plasmid transfer). 
In this case, the data which show that broad host-range plasmids can pick up 
chromosomal DNA from one species and transfer and have it expressed in another, 
even though guanine-cytosine contents of the DNA are highly divergent, could be 
used to argue that the existence of any transfer mechanism would allow for the 
formation of any and all recombinant types by natural means. Thus using the 
liberal philosophy one would include essentially all gram negative microorganisms 
and allow cloning from one to another in all reciprocal arrays. 
[A— 320] 
