Norberto Palleroni


Research Interests:

Norberto Palleroni (2nd from left) with Alexander Fleming (center) at the International Congresses of Microbiology in Rio de Janeiro in the 1950s.

I was born in Buenos Aires, Argentina. The education of children and young persons was taken from the French system, but now it has changed, in my opinion, for the worse. The similarity was more evident in the studies that ended in the baccalaureate. After the obligatory elementary grades, a young person has to follow with the secondary schools if the financial position of the family permits that. The system was very “French” in the institutions called “Colegios Nacionales”, to get a preparation required for any profession, with the exception of the commercial careers, which require special courses.

The basic education goes through 7 years of elementary education, and the National and Commercial Colleges may vary from 5 to 7 years. After my baccalaureate I entered the University in the School of Agronomic Engineering. The basic idea of this career is to consider that plants and farm animals are like machines, whose efficiency can be stimulated by physiological and/or genetic techniques. I was a good student, and in spite of money shortage of our home, I got out in the first category, with a beautiful diploma from which was hanging a beautiful gold medal. When I left home to continue my work somewhere else in the country, I left this gift in my home as a proof that I had reached a satisfactory end due not only of myself but also because the sacrifice of everyone of my relatives.

Soon after the end of my studies, I got a scholarship from Rotary International to come to the States, where I wanted to learn more biology, and I chose the Southern Illinois University, where Professor Carl C. Lindegren was the head of a group dedicated to yeast genetics. I stayed there for almost one year, and I was happy to reach interesting data which gave four publishable papers (one of them went to the important journal Nature, which was, of course, less demanding than today in the publication of scientific results).

Back in Argentina, I had an offer from the University of Cuyo, in Mendoza, a beautiful province that includes the highest peaks of the South American Andes. Shortly after this appointment, the John Simon Guggenheim Memorial Foundation gave me a fellowship to study metabolism of carbohydrates by bacteria, in particular, by a species that is now renamed, but at the time was very well known by biochemists as Pseudomonas saccharophila. At the beginning I worked mostly with an interesting enzyme that I found, capable for isomerizing free sugars, fructose and mannose. Using this enzyme, I was able to synthesizing a new disaccharide very similar to sucrose, glucosyl-D-rhamnulose. My work was related to the work of Professor Mike Doudoroff. However, my work was also discussed by Prof. Roger Y. Stanier, and I maintained a long and very profitable relationship with these two scientists. Dr Stanier was interested mainly in the metabolism of bacteria of the genus Pseudomonas, particularly the degradation of aromatic organic compounds.

Norberto Palleroni's "impersonation" of Beijerinck at the Laboratory of Microbiology at Delft University. The influence of Beijerinck and the "Delft School" of microbiology can be traced through the family tree of scientists: Santos Soriano who studied with Beijerinck was Norberto Palleroni's microbiology teacher.

In total I spent almost twenty years of my life in Berkeley, at the Department of Bacteriology of the University of California. During the first three years of my work I was supported by fellowships of the Guggenheim Foundation (years 1952, 1953 and 1954). I was quite fortunate in three fellowships by such a prestigious foundation. In successive years, the professors, and particular, Dr Mike Doudoroff gave me a salary coming from the support received from several sources for his research.

Several species of Pseudomonas were the subject of our research, and during our work it was a striking fact that although all the strains under study shared basic properties of their genus, there were also very deep differences which pointed to a high diversity in the collection. The results of our morphological and physiological characterization of Pseudomonas species was published in an enormous article in the Journal of General Microbiology [R. Y. Stanier, N. J. Palleroni and M. Doudoroff. The Aerobic Pseudomonads: a Taxonomic Study. J . Gen. Microbial. (1966), 43, 159-271; doi:10.1099/00221287-43-2-159]. The article became almost immediately a so-called “citation classic”. [Cited over 2000 times according to Google Scholar, Oct 2012].

In many discussions we had in the lab, Prof. Stanier insisted in the necessity of studying the genus to get a better knowledge of the basis of the great diversity within the genus. I started doing experiments in which I tried to define the heterogeneity of the DNA of members of the genus. In fact this heterogeneity was so profound, that there hardly any homology between some pairs of strains in the collection. In addition to the DNA results, the morphology and physiology of strains also pointed to the impossibility of withdrawing a convincing conclusion about the heterogeneity.

In the middle of my studies I had to visit my family in Buenos Aires, and as a reading material I took some of the work done in other laboratories on other groups of organisms, where they had observed very low or absent homology among ribosomal RNA of some of the groups of strains. In all the cases, however, there was a similarity among the groups, that is pairs, of strains of a genus could differ in the homology of the ribosomal RNA. When I came back to Berkeley, I had a meeting with Doudoroff and Stanier, and manifested the convenience of studying RNA homologies in the Pseudomonas species.

Since my experience with rRNA was rather limited, I spend a few weeks in the Department of Bacteriology of the University of Washington, in Seattle, WA, and in coming to Berkeley, I adapted the hybridization of the RNA samples using techniques with which I was familiar, because of their use in the DNA experiments. The results of the rRNA hybridization experiments were quite spectacular. The various species of the genus Pseudomonas pointed to the fact that Pseudomonas behaved as an entity of several genera. Pseudomonas was not a single genus, and I could recognize at least 5 genera starting with a collection representing the various previously known species. Soon after this finding, in the laboratory of Dr. John Johnson, using Clostridium, they could find a situation similar to Pseudomonas, that is, rRNA groups which appear similar to individual genera. In any case, soon after our findings using rRNA homology data, the use of this approach to taxonomy of bacteria became feasible and very illuminating.

During this phase of our work in Berkeley as part of the Doudoroff group, Dr. Stanier had only a marginal participation, because he moved to Paris. In any event, the work in this line was reaching an end, and the discovery of cancer in both great friends, mostly as consequence of their almost continuous inclination of having cigarettes in their lips. When we moved to Eastern U.S., Roger Stanier stayed with us, and also Mike Doudoroff gave me a call from the hospital where he had been operated and commented that the proportion of people escaping the vicious attack of cancer, was negligible. These two men were the most capable I found in my life and they were very dear friends.

I moved to the East (against the Buster Keaton recommendation of moving West) because I accepted an offer from the great Pharmaceutical Center, Hoffman-La Roche, where I was appointed as the taxonomist to keep in good shape all the organisms used in organic synthesis and in the production of antibiotics. I had to visit Japan in several occasions, to keep an eye on the culture collection, and similarly, I had to travel to Basel, in Switzerland for similar purposes. Originally, my appointed was a consequence of the interest that they have of isolating strains of poorly known, and I invented a method which consisted in trapping the motile spores of the strains of Actinoplanes inside of capillary tubes containing solutions of simple composition. With the capillaries I was able to isolated hundreds of strains, and later, to subject the strains to works on genetics, by producing protoplasts which could undergo fusion. Not too long ago I was able to repeat the hunting of Actinoplanes into capillary tubes, and Max and myself will take advantage of this approach for other interesting purposes. In summary, this is part of the story.

I cannot very well avoid a bit of personal pride, a stupid baroque attachment of the Italian personality. My deep interest in biology and in the bacteriology that I practiced for years of my life, I would like the fact that I received the present in the name of some of the friends that kept me alive. The species that carry my last name in the shape of bacteriological are: Pseudomonas palleroniana, Actinoplanes palleronii, Hydrogenophaga palleronii, and Genus Palleronia, of Mediterraneae bacteria with the species Palleronia marisminoris.

Pseudomonas palleroniana
International Journal of Systematic and Evolutionary Microbiology (2002), 52: 2065-2074. doi: 10.1099/ijs.0.02225-0

Actinoplanes palleronii
Microbiology (1990) 136: 19-36. doi: 10.1099/00221287-136-1-19

Hydrogenophaga palleronii
Int J Syst Bacteriol (1989) 39:319-333; doi:10.1099/00207713-39-3-319

Palleronia marisminoris
International Journal of Systematic and Evolutionary Microbiology (2005), 55: 2525-2530. doi: 10.1099/ijs.0.63906-0

Selected Publications:

The Pseudomonas Story. Environmental Microbiology. 2010, 12:1377-1383
Palleroni NJ

The Pseudomonas Story. Environmental Microbiology. 2010,
Palleroni NJ
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Prokaryote taxonomy of the 20th century and the impact of studies on the genus Pseudomonas: a personal view. Microbiology. 2003, 141:1-7
Pallerioni NJ

Prokaryote taxonomy of the 20th century and the impact of studies on the genus Pseudomonas: a personal view . Microbiology. 2003, 141, 1-7
Palleroni NJ
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Pseudomonas classification: A new case history in the taxonomy of Gram-negative bacteria. Antonie van Leeuwenhoek. 1993, 64: 231-251
Palleroni NJ

Stenotrophomonas, a new bacterial genus for Xanthomonas maltophilia (Hugh 1980) Swings et al. 1983. Int J System Evol Microbiol. 1993, 43:606-609
Palleroni NJ, and John F. Bradbury JF
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Introduction to the family Pseudomonadaceae. In: The Prokaryotes. . 1992,
Palleroni NJ

Prokaryotic diversity and the importance of culturing. Antonie van Leeuwenhoek. 1977, 72: 3-19
Palleroni NJ

Chamber for bacterial chemotaxis experiments. Appl Environ Microbiol. 1976, 32: 729-730
Palleroni NJ

Nucleic acid homologies in the genus Pseudomonas. Int J System Bacteriol. 1973, 23:333-339
Palleroni NJ, Kunisawa R, Contopoulou R and Doudoroff M
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The aerobic Pseudomonads: A taxonomic study. Microbiology. 1970, 43:159-271
Stanier RY, Palleroni NJ and Doudoroff M
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Taxonomy of the aerobic pseudomonads: Pseudomonas cepacia, P. marginata, P. alliicola and P. caryophylli.. Microbiology. 1966, 60:199-214
Ballard RW, Palleroni NJ, Doudoroff M, Stanier RY and Mandel M
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