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[SANET-MG] GM bacteria joined to plants
April 22, 2004
Prof. Joe cummins
?Engineered bacteria joined to plants for remediation of chemical pollutants
may cleanup pollution but also spread disease?
Recently the journal Nature Biotechnology featured an article showing that
phytoremediation ( pollution elimination using plants) could be greatly
improved by genetically modifying (GM) pollution destroying bacteria living
within the plant tissues (endophyte). The bacterium modified was Burkholderia
cepacia a natural resident of the yellow lupine. The plant modified with the
GM bacterium took up the pollutant toluene from the soil and the GM bacteria
destroyed the pollutant rather than releasing it to the atmosphere. The plant
bearing a GM bacterium provided a potent tool for remediating polluted soil
(1). The research report failed to mention that Burkolderia cepacia has the
ability to cause fatal disease in humans as will be described below.
The groundwater of Wichita,Kansas was found to polluted with chemical
solvents dichloroethylene and trichloroethylene and that pollution was
remediated using a natural strain of Burkholderia cepacia (2). Neither
special public health measures nor epidemiological follow up seemed to have
followed the remediation.
The United states Environmental Protection Agency (EPA) has considered the
problems associated with approval of Burkholderia cepacia as a plant
pesticide, not only is the bacterium used to fight plant pests but is itself
a plant pest as well as it is a disease agent in human. EPA , through a
Scientific Advisory Panel (SAP) reviewed Burkholderia cepacia (Bc) as a plant
pesticide and acknowledged the link to human disease (3,4). The SAP risk
assessment peculiarly noted ?Bc has been referred to as an opportunistic human
pathogen. However, as might be expected, the strains registered or proposed for
use as biopesticides were isolated from the soil or plant roots,rather than
from human patients?(4) In reality , as will be shown below, the SAP comment
offered cold comfort because the Bc strains isolated from patients proved
essentially undistinguishable from strains isolated from the roots of crops
such as corn. The American Phytopathological Society has proved a useful
review of the risks from plant disease ,or human disease along with the
benefits in remediating chemical pollution and fighting some plant
diseases(5). Unfortunately, there has been no clear and simple way to
differentiate between the evil and the beneficial strains of Bc and no way of
preventing the two from exchanging genes.
Burkhoderia cepacia (Bc) has an unusual genetic makeup, the Bc strains have
a relatively large amount of DNA (about twice that of E. coli) and unlike most
bacteria, that usually have a single chromosome, Bc strains have as many as
five large replicons (chromosomes) and the different chromosomes are rich in
insertion sequences that allow for extensive gene exchange between different
Bc strains and insertion of disease related genes from other bacterial
species (6). Bc is a prominent cause of death among cystic fibrosis patients,
the bacterium frequently reaches epidemic proportion among such patients and an
epidemic related strain was identified in soil samples in USA (7). Bc is
believed to be a complex species made up of seven distinct genomic sub species
all of which are capable of infecting humans, even though genomovar III
(subspecies) is most frequently associated with epidemics., all of the disease
related genomovars of Bc were isolated from maize rhizosphere (root ecology)
(8). Bc pathology is difficult to contain because disease bacteria may be
replenished continually from the soil and plant material.
Nosocomial (hospital based) Bc epidemics appeared among patients with
diabetes, malignancy, heart failure and chronic obstructive pulmonary disease
(9). A nosocomial Bc outbreak appeared in an intensive pediatric care unit
(10). Bc infection was common among renal transplants (11). Different CF clones
showed differing infectivity among cystic fibrosis patients and patients with
different complaints (12,13) Antibiotic resistant Bc infection was the most
common cause of death among lung transplants for cystic fibrosis patients
(14). Bc causes feared infections because the strains tend to be antibiotic
resistant. Bc isolated from different infections were found to be resistant to
all seven tested antibiotics but were sensitive to treatment with honey (14).
Clearly there is a large literature on the threat of Burkhoderia cepacia
infection and its large death toll among compromised patients. Here-to fore,
the existing evidence indicates that the bacterial infections may pass from
the ecosystem to the hospital ward and there seems no way of insuring that the
Bc strains used in biotechnology are unable to infect compromised humans.
Science reporting is based on a foundation of full and truth full reporting and
the failure of journal editors to insure that the detrimental effects of
biological agents being promoted are fully reported seems negligent.
Unfortunately, biotechnology science reporting seems to have taken on the
characteristics of public relations promotion.
1. Barac,T,Taghavi,S,Borremans,B, Provoost,A, Oeyen,L,
Colpaert,J,Vangronsveld,J. and van der Lelie,D. ?Engineered endophytic bacteria
improve phytoremediation of water-soluble, volatile, organic pollutants? 2004
nature biotech online: 11 April doi:10.1038/nbt960
2. Mostellar,D,Borguin,A and Olsen,Camp Dressler and McKee Inc. ?Aerobic
bioremediation of TCE contaminated ground water: bioaugmentation with
Burkholderia cepacia PR301? 1997 Bioremedation Kansa B pp1-4
3. United States EPA ?Report FIFRA scientific advisory panel meeting july
20-23,1999 session1-Burkholderia cepacia : risk assessment of a biopesticide
with afffinities to a human opportunistic pathogen? 1999 SAP Report No. 99-04
4. United States EPA ?Risk assessment of Burkholderia cepacia based
biopesticides and other pathogens related to oppoetunistic human pathogens?
5. Parke,J.?Burkholderia cepacia :friend or foe?? 2000 The education center of
the American Phytopathologial Society pp1-8
6. Wigley,P and Burton,N. ?Multiple chromosomes in Burkholderia cepacia and B.
gladioli and their distribution on clinical andenvironmental strains of B.
cepacia? 2000 J. Applied Microbiology 88,914-8
7. LiPuma J, Spilker T, Coenye T. and Gonzalez C. ?An epidemic Burkholderia
cepacia complex strain identified in soil.? 2002 Lancet 359,2002-3
8. Fiore,A,Laevens,S,Bevivino,A,Dalmastri,C,Tabacchioni,S,Vandamme,P. and
Chiarini,L. ?Burkholderia cepacia complex: distribution of genomovars among
isolates from the maize rhizosphere in Italy? 2001 Environmental Microbiology
9. Huang, C, Jang,T, Liu ,C, Fung ,C, Yu ,K. and Wong ,W. ?Characteristics of
patients with Burkholderia cepacia bacteremia.? 2001 J Microbiol Immunol
10. Bureau-Chalot ,F, Piednoir,E,Pierrat,C, Santerne ,B. and Bajolet,O.
?Nosocomial Burkholderia cepacia outbreak in an intensive pediatric care unit?
2003 Archives de pédiatrie 10 , 882?88
11. Li,F,Chan,K,Chan,T. and Lai,K. ?Burkholderia urinary tract infection after
renal transoplantation? 2003, Transplant Infect. Dis, 5,59-61
12. Agodi A, Barchitta M, Giannino V, Collura A, Pensabene T, Garlaschi
M,Pasquarella C, Luzzaro F, Sinatra F, Mahenthiralingam E. and Stefani, S.
?Burkholderia cepacia complex in cystic fibrosis and non-cystic fibrosis
patients: identification of a cluster of epidemic lineages.?2002
13. Manno,G, Dalmastri,C, Tabacchioni,S, Vandamme,P, Lorini,R, Minicucci,L,
Romano,L, Giannattasio,A, Chiarini,L.and Bevivino,A. ?Epidemiology and Clinical
Course of Burkholderia cepacia Complex Infections, Particularly Those Caused by
Different Burkholderia cenocepacia Strains, among Patients Attending an Italian
Cystic Fibrosis Center? 2004, journal of clinical microbiology 42,1491-7
14. Dobbina,C, Maleyb,M,Harknessc,J, Bennd,R,Maloufe,M, Glanvillee,A. and .
Byea,P. ?The impact of pan-resistant bacterial pathogens on survival after
lung transplantation in cystic fibrosis:results from a single large referral
centre? 2004 Journal of Hospital Infection 56,277-82
15. Cooper,R, Wigley,P. and Burton,N. ?Susceptibility of multiresistant
strains of Burkholderia cepacia to honey? 2000 Letters in Applied
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