1
|
Belousova ME, Malovichko YV, Shikov AE, Nizhnikov AA, Antonets KS. Dissecting the Environmental Consequences of Bacillus thuringiensis Application for Natural Ecosystems. Toxins (Basel) 2021; 13:toxins13050355. [PMID: 34065665 PMCID: PMC8155924 DOI: 10.3390/toxins13050355] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 05/10/2021] [Accepted: 05/13/2021] [Indexed: 12/30/2022] Open
Abstract
Bacillus thuringiensis (Bt), a natural pathogen of different invertebrates, primarily insects, is widely used as a biological control agent. While Bt-based preparations are claimed to be safe for non-target organisms due to the immense host specificity of the bacterium, the growing evidence witnesses the distant consequences of their application for natural communities. For instance, upon introduction to soil habitats, Bt strains can affect indigenous microorganisms, such as bacteria and fungi, and further establish complex relationships with local plants, ranging from a mostly beneficial demeanor, to pathogenesis-like plant colonization. By exerting a direct effect on target insects, Bt can indirectly affect other organisms in the food chain. Furthermore, they can also exert an off-target activity on various soil and terrestrial invertebrates, and the frequent acquisition of virulence factors unrelated to major insecticidal toxins can extend the Bt host range to vertebrates, including humans. Even in the absence of direct detrimental effects, the exposure to Bt treatment may affect non-target organisms by reducing prey base and its nutritional value, resulting in delayed alleviation of their viability. The immense phenotypic plasticity of Bt strains, coupled with the complexity of ecological relationships they can engage in, indicates that further assessment of future Bt-based pesticides' safety should consider multiple levels of ecosystem organization and extend to a wide variety of their inhabitants.
Collapse
Affiliation(s)
- Maria E. Belousova
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (M.E.B.); (Y.V.M.); (A.E.S.); (A.A.N.)
| | - Yury V. Malovichko
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (M.E.B.); (Y.V.M.); (A.E.S.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Anton E. Shikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (M.E.B.); (Y.V.M.); (A.E.S.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Anton A. Nizhnikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (M.E.B.); (Y.V.M.); (A.E.S.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Kirill S. Antonets
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (M.E.B.); (Y.V.M.); (A.E.S.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University, 199034 St. Petersburg, Russia
- Correspondence:
| |
Collapse
|
2
|
Aerosol and Surface Deposition Characteristics of Two Surrogates for Bacillus anthracis Spores. Appl Environ Microbiol 2016; 82:6682-6690. [PMID: 27613681 DOI: 10.1128/aem.02052-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 08/22/2016] [Indexed: 01/22/2023] Open
Abstract
Spores of an acrystalliferous derivative of Bacillus thuringiensis subsp. kurstaki, termed Btcry-, are morphologically, aerodynamically, and structurally indistinguishable from Bacillus anthracis spores. Btcry- spores were dispersed in a large, open-ended barn together with spores of Bacillus atrophaeus subsp. globigii, a historically used surrogate for Bacillus anthracis Spore suspensions (2 × 1012 CFU each of B. atrophaeus subsp. globigii and Btcry-) were aerosolized in each of five spray events using a backpack misting device incorporating an air blower; a wind of 4.9 to 7.6 m s-1 was also flowing through the barn in the same direction. Filter air samplers were situated throughout the barn to assess the aerosol density of the spores during each release. Trays filled with a surfactant in aqueous buffer were placed on the floor near the filter samplers to assess spore deposition. Spores were also recovered from arrays of solid surfaces (concrete, aluminum, and plywood) that had been laid on the floor and set up as a wall at the end of the barn. B. atrophaeus subsp. globigii spores were found to remain airborne for significantly longer periods, and to be deposited on horizontal surfaces at lower densities, than Btcry- spores, particularly near the spray source. There was a 6-fold-higher deposition of Btcry- spores than of B. atrophaeus subsp. globigii spores on vertical surfaces relative to the surrounding airborne density. This work is relevant for selecting the best B. anthracis surrogate for the prediction of human exposure, hazard assessment, and hazard management following a malicious release of B. anthracis IMPORTANCE: There is concern that pathogenic bacteria could be maliciously disseminated in the air to cause human infection and disruption of normal life. The threat from spore-forming organisms, such as the causative agent of anthrax, is particularly serious. In order to assess the extent of this risk, it is important to have a surrogate organism that can be used to replicate the dispersal characteristics of the threat agent accurately. This work compares the aerosol dispersal and deposition behaviors of the surrogates Btcry- and B. atrophaeus subsp. globigii Btcry- spores remained in the air for a shorter time, and were markedly more likely to adhere to vertical surfaces, than B. atrophaeus subsp. globigii spores.
Collapse
|
3
|
Risks for public health related to the presence of Bacillus cereus and other Bacillus spp. including Bacillus thuringiensis in foodstuffs. EFSA J 2016. [DOI: 10.2903/j.efsa.2016.4524] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
|
4
|
Yu Z, Xiong J, Zhou Q, Luo H, Hu S, Xia L, Sun M, Li L, Yu Z. The diverse nematicidal properties and biocontrol efficacy of Bacillus thuringiensis Cry6A against the root-knot nematode Meloidogyne hapla. J Invertebr Pathol 2014; 125:73-80. [PMID: 25556591 DOI: 10.1016/j.jip.2014.12.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 12/13/2014] [Accepted: 12/23/2014] [Indexed: 11/18/2022]
Abstract
Cry6A toxin from Bacillus thuringiensis is a representative nematicidal crystal protein with a variety of nematicidal properties to free-living nematode Caenorhabditis elegans. Cry6A shares very low homology and different structure with Cry5B, another representative nematicidal crystal protein, and probably acts in a distinct pathway. All these strongly indicate that Cry6A toxin is likely a potent candidate for nematicide. The present study dealt with global investigation to determine the detrimental impacts of Cry6Aa2 toxin on Meloidogyne hapla, a root-knot nematode, and evaluated its biocontrol efficacy in pot experiment. Obtained results indicated that Cry6Aa2 toxin exhibits obvious toxicity to second-stage juvenile of M. hapla, and significantly inhibits egg hatch, motility, and penetration to host plant. Pot experiment suggested that soil drenching with spore-crystal mixture of Cry6Aa2 can clearly lighten the disease of root-knot nematode, including reduction of galling index and egg masses on host plant root, decreasing final population of nematode in soil. Moreover, application of Cry6Aa2 can obviously promote plant growth. These results demonstrated that Cry6Aa2 toxin is a promising nematicidal agent, and possesses great potential in plant-parasitic nematode management and construction of transgenic crop with constant resistance to nematode.
Collapse
Affiliation(s)
- Ziquan Yu
- State Key Laboratory of Breeding Base of Microbial Molecular Biology, College of Life Science, Hunan Normal University, Changsha 410081, PR China.
| | - Jing Xiong
- State Key Laboratory of Breeding Base of Microbial Molecular Biology, College of Life Science, Hunan Normal University, Changsha 410081, PR China
| | - Qiaoni Zhou
- State Key Laboratory of Breeding Base of Microbial Molecular Biology, College of Life Science, Hunan Normal University, Changsha 410081, PR China
| | - Haiyan Luo
- State Key Laboratory of Breeding Base of Microbial Molecular Biology, College of Life Science, Hunan Normal University, Changsha 410081, PR China
| | - Shengbiao Hu
- State Key Laboratory of Breeding Base of Microbial Molecular Biology, College of Life Science, Hunan Normal University, Changsha 410081, PR China
| | - Liqiu Xia
- State Key Laboratory of Breeding Base of Microbial Molecular Biology, College of Life Science, Hunan Normal University, Changsha 410081, PR China
| | - Ming Sun
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Lin Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Ziniu Yu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| |
Collapse
|
5
|
Guidi V, Lehner A, Lüthy P, Tonolla M. Dynamics of Bacillus thuringiensis var. israelensis and Lysinibacillus sphaericus spores in urban catch basins after simultaneous application against mosquito larvae. PLoS One 2013; 8:e55658. [PMID: 23390547 PMCID: PMC3563526 DOI: 10.1371/journal.pone.0055658] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 12/28/2012] [Indexed: 11/23/2022] Open
Abstract
Bacillus thuringiensis var. israelensis (Bti) and Lysinibacillus sphaericus (Lsph) are extensively used in mosquito control programs. These biocides are the active ingredients of a commercial larvicide. Quantitative data on the fate of both Bti and Lsph applied together for the control of mosquitoes in urban drainage structures such as catch basins are lacking. We evaluated the dynamics and persistence of Bti and Lsph spores released through their concomitant application in urban catch basins in southern Switzerland. Detection and quantification of spores over time in water and sludge samples from catch basins were carried out using quantitative real-time PCR targeting both cry4A and cry4B toxin genes for Bti and the binA gene for Lsph. After treatment, Bti and Lsph spores attained concentrations of 3.76 (±0.08) and 4.13 (±0.09) log ml−1 in water, then decreased progressively over time, reaching baseline values. For both Bti and Lsph, spore levels in the order of 105 g−1 were observed in the bottom sludge two days after the treatment and remained constant for the whole test period (275 days). Indigenous Lsph strains were isolated from previously untreated catch basins. A selection of those was genotyped using pulsed field gel electrophoresis of SmaI-digested chromosomal DNA, revealing that a subset of isolates were members of the clonal population of strain 2362. No safety issues related to the use of this biopesticide in the environment have been observed during this study, because no significant increase in the number of spores was seen during the long observation period. The isolation of native Lysinibacillus sphaericus strains belonging to the same clonal population as strain 2362 from catch basins never treated with Lsph-based products indicates that the use of a combination of Bti and Lsph for the control of mosquitoes does not introduce non-indigenous microorganisms in this area.
Collapse
Affiliation(s)
- Valeria Guidi
- Microbial Ecology Group, Microbiology Unit, Plant Biology Department, University of Geneva, Genève, Switzerland
- Institute of Microbiology, Bellinzona, Switzerland
| | - Angelika Lehner
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zürich, Switzerland
| | - Peter Lüthy
- Institute of Microbiology, ETH Zürich, Zürich, Switzerland
| | - Mauro Tonolla
- Microbial Ecology Group, Microbiology Unit, Plant Biology Department, University of Geneva, Genève, Switzerland
- Institute of Microbiology, Bellinzona, Switzerland
- * E-mail:
| |
Collapse
|
6
|
Hendriksen NB, Carstensen J. Long-term survival of Bacillus thuringiensis subsp. kurstaki in a field trial. Can J Microbiol 2013; 59:34-8. [PMID: 23391227 DOI: 10.1139/cjm-2012-0380] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Long-term survival of Bacillus thuringiensis subsp. kurstaki DMU67R has been investigated in a field trial. An experimental cabbage plot was sprayed with DMU67R in 1993 and was allowed to lie fallow since then. The investigation reported here was carried out from 2001 to 2007 in a single square meter within the plot using a systematic randomized sampling approach. The bacterium survived at relative low densities in these 13 years after spraying. Statistical analyses revealed that the overall density decreased approximately 40% during years 8 to 13 after the application; however, the trend was not uniform and contained periods of both increases and decreases in density of DMU67R, with decreases in density notably related to conditions of low water content in the soil. Long-term survival of DMU67R in this field plot seems to include germination and growth, possibly related to growth in insect hosts, and death or inactivation during dry periods, both phases occurring during May to October where the soil temperature exceeds 10 °C.
Collapse
Affiliation(s)
- Niels Bohse Hendriksen
- Department of Environmental Science, Aarhus University, Frederiksborgvej 399, DK-4000 Roskilde, Denmark.
| | | |
Collapse
|
7
|
Van Cuyk S, Deshpande A, Hollander A, Duval N, Ticknor L, Layshock J, Gallegos-Graves L, Omberg KM. Persistence of Bacillus thuringiensis subsp. kurstaki in Urban Environments following Spraying. Appl Environ Microbiol 2011; 77:7954-61. [PMID: 21926205 PMCID: PMC3208992 DOI: 10.1128/aem.05207-11] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 08/26/2011] [Indexed: 11/20/2022] Open
Abstract
Bacillus thuringiensis subsp. kurstaki is applied extensively in North America to control the gypsy moth, Lymantria dispar. Since B. thuringiensis subsp. kurstaki shares many physical and biological properties with Bacillus anthracis, it is a reasonable surrogate for biodefense studies. A key question in biodefense is how long a biothreat agent will persist in the environment. There is some information in the literature on the persistence of Bacillus anthracis in laboratories and historical testing areas and for Bacillus thuringiensis in agricultural settings, but there is no information on the persistence of Bacillus spp. in the type of environment that would be encountered in a city or on a military installation. Since it is not feasible to release B. anthracis in a developed area, the controlled release of B. thuringiensis subsp. kurstaki for pest control was used to gain insight into the potential persistence of Bacillus spp. in outdoor urban environments. Persistence was evaluated in two locations: Fairfax County, VA, and Seattle, WA. Environmental samples were collected from multiple matrices and evaluated for the presence of viable B. thuringiensis subsp. kurstaki at times ranging from less than 1 day to 4 years after spraying. Real-time PCR and culture were used for analysis. B. thuringiensis subsp. kurstaki was found to persist in urban environments for at least 4 years. It was most frequently detected in soils and less frequently detected in wipes, grass, foliage, and water. The collective results indicate that certain species of Bacillus may persist for years following their dispersal in urban environments.
Collapse
Affiliation(s)
- Sheila Van Cuyk
- Los Alamos National Laboratory, MS F606, P.O. Box 1663, Los Alamos, NM 87545, USA.
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Distribution of Bacillus thuringiensis subsp. israelensis in Soil of a Swiss Wetland reserve after 22 years of mosquito control. Appl Environ Microbiol 2011; 77:3663-8. [PMID: 21498758 DOI: 10.1128/aem.00132-11] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recurrent treatments with Bacillus thuringiensis subsp. israelensis are required to control the floodwater mosquito Aedes vexans that breeds in large numbers in the wetlands of the Bolle di Magadino Reserve in Canton Ticino, Switzerland. Interventions have been carried out since 1988. In the present study, the spatial distribution of resting B. thuringiensis subsp. israelensis spores in the soil was measured. The B. thuringiensis subsp. israelensis concentration was determined in soil samples collected along six transects covering different elevations within the periodically flooded zones. A total of 258 samples were processed and analyzed by quantitative PCR that targeted an identical fragment of 159 bp for the B. thuringiensis subsp. israelensis cry4Aa and cry4Ba genes. B. thuringiensis subsp. israelensis spores were found to persist in soils of the wetland reserve at concentrations of up to 6.8 log per gram of soil. Continuous accumulation due to regular treatments could be excluded, as the decrease in spores amounted to 95.8% (95% confidence interval, 93.9 to 97.7%). The distribution of spores was correlated to the number of B. thuringiensis subsp. israelensis treatments, the elevation of the sampling point, and the duration of the flooding periods. The number of B. thuringiensis subsp. israelensis treatments was the major factor influencing the distribution of spores in the different topographic zones (P < 0.0001). These findings indicated that B. thuringiensis subsp. israelensis spores are rather immobile after their introduction into the environment.
Collapse
|
9
|
Greenberg DL, Busch JD, Keim P, Wagner DM. Identifying experimental surrogates for Bacillus anthracis spores: a review. INVESTIGATIVE GENETICS 2010; 1:4. [PMID: 21092338 PMCID: PMC2988482 DOI: 10.1186/2041-2223-1-4] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Accepted: 09/01/2010] [Indexed: 01/05/2023]
Abstract
Bacillus anthracis, the causative agent of anthrax, is a proven biological weapon. In order to study this threat, a number of experimental surrogates have been used over the past 70 years. However, not all surrogates are appropriate for B. anthracis, especially when investigating transport, fate and survival. Although B. atrophaeus has been widely used as a B. anthracis surrogate, the two species do not always behave identically in transport and survival models. Therefore, we devised a scheme to identify a more appropriate surrogate for B. anthracis. Our selection criteria included risk of use (pathogenicity), phylogenetic relationship, morphology and comparative survivability when challenged with biocides. Although our knowledge of certain parameters remains incomplete, especially with regards to comparisons of spore longevity under natural conditions, we found that B. thuringiensis provided the best overall fit as a non-pathogenic surrogate for B. anthracis. Thus, we suggest focusing on this surrogate in future experiments of spore fate and transport modelling.
Collapse
Affiliation(s)
- David L Greenberg
- Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011-4073, USA
| | - Joseph D Busch
- Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011-4073, USA
| | | | - David M Wagner
- Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011-4073, USA
| |
Collapse
|
10
|
Monnerat RG, Soares CM, Capdeville G, Jones G, Martins ES, Praça L, Cordeiro BA, Braz SV, dos Santos RC, Berry C. Translocation and insecticidal activity of Bacillus thuringiensis living inside of plants. Microb Biotechnol 2009; 2:512-20. [PMID: 21255282 PMCID: PMC3815911 DOI: 10.1111/j.1751-7915.2009.00116.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The major biological pesticide for the control of insect infestations of crops, Bacillus thuringiensis was found to be present naturally within cotton plants from fields that had never been treated with commercial formulations of this bacterium. The ability of B. thuringiensis to colonize plants as an endophyte was further established by the introduction of a strain marked by production of green fluorescent protein (GFP). After inoculation of this preparation close to the roots of cotton and cabbage seedlings, GFP-marked bacteria could be re-isolated from all parts of the plant, having entered the roots and migrated through the xylem. Leaves taken from the treated plants were able to cause toxicity when fed to the Lepidoptera Spodoptera frugiperda (cotton) and Plutella xylostella (cabbage). These results open up new horizons for understanding the natural ecology and evolution of B. thuringiensis and use of B. thuringiensis in insect control.
Collapse
Affiliation(s)
- Rose Gomes Monnerat
- Embrapa Recursos Geneticos e Biotecnologia, Parque Estação Biológica, Av W/5 Norte (final), CEP 70 770-900, Caixa Postal 02372, Brasília DF, Brazil.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Bizzarri MF, Bishop AH. The ecology of Bacillus thuringiensis on the Phylloplane: colonization from soil, plasmid transfer, and interaction with larvae of Pieris brassicae. MICROBIAL ECOLOGY 2008; 56:133-9. [PMID: 17973155 DOI: 10.1007/s00248-007-9331-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Accepted: 10/02/2007] [Indexed: 05/05/2023]
Abstract
Seedlings of clover (Triflorium hybridum) were colonized by Bacillus thuringiensis when spores and seeds were co-inoculated into soil. Both a strain isolated in the vegetative form from the phylloplane of clover, 2810-S-4, and a laboratory strain, HD-1, were able to colonize clover to a density of about 1000 CFU/g leaf when seeds were sown in sterile soil and to a density of about 300 CFU/g leaf in nonsterile soil. A strain lacking the characteristic insecticidal crystal proteins produced a similar level of colonization over a 5-week period as the wild type strain, indicating that crystal production was not a mitigating factor during colonization. A small plasmid, pBC16, was transferred between strains of B. thuringiensis when donor and recipient strains were sprayed in vegetative form onto leaves of clover and pak choi (Brassica campestris var. chinensis). The rate of transfer was about 0.1 transconjugants/recipient and was dependent on the plant species. The levels of B. thuringiensis that naturally colonized leaves of pak choi produced negligible levels of mortality in third instar larvae of Pieris brassicae feeding on the plants. Considerable multiplication occurred in the excreted frass but not in the guts of living insects. Spores in the frass could be a source of recolonization from the soil and be transferred to other plants. These findings illustrate a possible cycle, not dependent on insect pathology, by which B. thuringiensis diversifies and maintains itself in nature.
Collapse
Affiliation(s)
- M F Bizzarri
- School of Science, University of Greenwich, Chatham Maritime, UK
| | | |
Collapse
|
12
|
Magkos F, Arvaniti F, Zampelas A. Putting the safety of organic food into perspective. Nutr Res Rev 2007; 16:211-22. [DOI: 10.1079/nrr200361] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The demand for organic foods is constantly increasing mainly due to consumers' perception that they are healthier and safer than conventional foods. There is a need for information related to food safety to inform consumers of the health benefits and/or hazards of food products of both origins, in order to optimise the impact on health and minimise the risks. Several gaps and limitations in scientific knowledge with regard to food risk evaluation make it difficult to draw generalised conclusions. Still, some organic foods can be expected to contain fewer agrochemical residues and lower levels of nitrate than conventionally grown alternatives. On the other hand, environmental contaminants are equally present in foods of both origins. With regard to other food hazards, such as natural chemicals, microbial pathogens and mycotoxins, no clear conclusions can be drawn, although several interesting points can be highlighted. It is difficult, therefore, to weigh the risks, but what should be made clear to consumers is that ‘organic’ does not equal ‘safe’. If producers adopt proper agricultural practices and consumers maintain hygienic conditions, risks associated with food contaminants can be minimised, regardless of the food's organic or conventional origin.
Collapse
|
13
|
Bizzarri MF, Bishop AH. Recovery of Bacillus thuringiensis in vegetative form from the phylloplane of clover (Trifolium hybridum) during a growing season. J Invertebr Pathol 2007; 94:38-47. [PMID: 17005192 DOI: 10.1016/j.jip.2006.08.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2006] [Revised: 08/14/2006] [Accepted: 08/16/2006] [Indexed: 11/23/2022]
Abstract
Two media were developed which specifically allow the cultivation of Bacillus thuringiensis while it is in the vegetative as opposed to the spore form. Using these media B. thuringiensis was shown conclusively for the first time to exist in an active form on the phylloplane. The profile of its appearance in vegetative and spore form was followed over a growing season on clover (Trifolium hybridum) in the field. Three simultaneous and sudden rises and declines of both spore and vegetative cell densities were observed. The most common other spore-former on these leaves was Bacillus cereus but the fluctuations in appearance of these two very closely related species were not co-incident. Using specific PCR primers a considerable diversity of cry toxin gene types was found in isolates that had been recovered in vegetative form ('vegetative isolates') with the majority possessing multiple delta-endotoxin genes while some had only one of those tested. Bioassays against a lepidopteran insect of purified delta-endotoxins showed that they were no more potent than those from a laboratory-adapted strain. PCR primers for an internal region of the vip3A gene produced amplification in 70% of the vegetative isolates compared to 25% of the laboratory-adapted strains tested.
Collapse
|
14
|
Magkos F, Arvaniti F, Zampelas A. Organic Food: Buying More Safety or Just Peace of Mind? A Critical Review of the Literature. Crit Rev Food Sci Nutr 2006; 46:23-56. [PMID: 16403682 DOI: 10.1080/10408690490911846] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Consumer concern over the quality and safety of conventional food has intensified in recent years, and primarily drives the increasing demand for organically grown food, which is perceived as healthier and safer. Relevant scientific evidence, however, is scarce, while anecdotal reports abound. Although there is an urgent need for information related to health benefits and/or hazards of food products of both origins, generalized conclusions remain tentative in the absence of adequate comparative data. Organic fruits and vegetables can be expected to contain fewer agrochemical residues than conventionally grown alternatives; yet, the significance of this difference is questionable, inasmuch as actual levels of contamination in both types of food are generally well below acceptable limits. Also, some leafy, root, and tuber organic vegetables appear to have lower nitrate content compared with conventional ones, but whether or not dietary nitrate indeed constitutes a threat to human health is a matter of debate. On the other hand, no differences can be identified for environmental contaminants (e.g. cadmium and other heavy metals), which are likely to be present in food from both origins. With respect to other food hazards, such as endogenous plant toxins, biological pesticides and pathogenic microorganisms, available evidence is extremely limited preventing generalized statements. Also, results for mycotoxin contamination in cereal crops are variable and inconclusive; hence, no clear picture emerges. It is difficult, therefore, to weigh the risks, but what should be made clear is that 'organic' does not automatically equal 'safe.' Additional studies in this area of research are warranted. At our present state of knowledge, other factors rather than safety aspects seem to speak in favor of organic food.
Collapse
Affiliation(s)
- Faidon Magkos
- Laboratory of Nutrition and Clinical Dietetics, Department of Nutrition and Dietetics, Harokopio University, 70 El. Venizelou Ave, Kallithea, Athens, 176 71, Greece
| | | | | |
Collapse
|
15
|
Molecular approaches for identification and construction of novel insecticidal genes for crop protection. World J Microbiol Biotechnol 2005. [DOI: 10.1007/s11274-005-9027-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
16
|
Hajaij M, Carron A, Deleuze J, Gaven B, Setier-Rio ML, Vigo G, Thiéry I, Nielsen-LeRoux C, Lagneau C. Low persistence of Bacillus thuringiensis serovar israelensis spores in four mosquito biotopes of a salt marsh in southern France. MICROBIAL ECOLOGY 2005; 50:475-87. [PMID: 16328650 DOI: 10.1007/s00248-005-0247-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2004] [Accepted: 04/12/2005] [Indexed: 05/05/2023]
Abstract
We studied the persistence of Bacillus thuringiensis serovar israelensis (Bti) in a typical breeding site of the mosquito Ochlerotatus caspius in a particularly sensitive salt marsh ecosystem following two Bti-based larvicidal applications (Vectobac 12AS, 1.95 L/ha). The treated area was composed of four larval biotopes that differed in terms of the most representative plant species (Sarcocornia fruticosa, Bolboschoenus maritimus, Phragmites australis, and Juncus maritimus) and the physical and chemical characteristics of the soil. We sampled water, soil, and plants at various times before and after the applications (from spring to autumn, 2001) and quantified the spores of B. thuringiensis (Bt) and Bacillus species. The B. cereus group accounted for between 0% and 20% of all Bacillus spp. before application depending on the larval biotope. No Bti were found before application. The variation in the quantity of bacilli during the mosquito breeding season depended more on the larval biotope than on the season or the larvicidal application. More bacilli were found in soil (10(4)-10(6) spores/g) than on plant samples (10(2)-10(4) spores/g). The abundance in water (10(5) to 10(7) spores/L) appeared to be correlated to the water level of the breeding site. The number of Bti spores increased just after application, after declining; no spores were detected in soil or water 3 months after application. However, low numbers of Bti spores were present on foliage from three of the four studied plant strata. In conclusion, the larvicidal application has very little impact on Bacillus spp. flora after one breeding season (two applications).
Collapse
Affiliation(s)
- Myriam Hajaij
- Bactéries et Champignons Entomopathogènes, Institut Pasteur, Paris, France
| | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Hendriksen NB, Hansen BM. Long-term survival and germination of Bacillus thuringiensis var. kurstaki in a field trial. Can J Microbiol 2002; 48:256-61. [PMID: 11989770 DOI: 10.1139/w02-009] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Long-term survival, dispersal, and germination of Bacillus thuringiensis var. kurstaki DMU67R has been investigated in a field trial. An experimental cabbage plot was sprayed with DMU67R in 1993 and allowed to lie fallow since. The investigations reported here were carried out from 1997 to 2000 in this plot. High persistence of DMU67R for 7 years in the bulk soil of the plot has been demonstrated. The numbers have not significantly reduced since 1994, stabilizing around 6.6 x 10(2) cfu/g from 1996 to 2000. Horizontal dispersal of DMU67R in the 1994-1999 period was limited. Vertical dispersal occurred from 1994 to 1999, as 77% of the population of DMU67R occurred in the 0-2 cm layer in 1994, while only 22% of the population was found there in 1999. Most of the population in 1999 was present homogeneously in the upper 6 cm of the soil profile. Germination, as evidenced by the ratio of DMU67R cfu before and after heat treatment, was not observed in the bulk soil. However, in the rhizospheres of dandelion (Taraxacum officinalis) and quackgrass (Agropyron repens), 40 and 50% of DMU67R was present as vegetative germinated cells, respectively. No germination occurred in the rhizosphere of red fescue (Festuca rubra). The material from the gut of the earthworm species Lumbricus rubellus, Lumbricus terrestris, and Apporrectodea caliginosa and from a tipulid larvae from the plot also contained vegetative cells of DMU67R. Further investigations of A. caliginosa showed that germination seemed to be restricted to the gut and that sporulation occurred after defecation. The germination of DMU67R in rhizospheres and in the gut of nontarget invertebrates suggests that survival in the soil of B. thuringiensis is a dynamic process involving germination, cell divisions, and sporulation in specific microhabitats.
Collapse
Affiliation(s)
- Niels Bohse Hendriksen
- National Environmental Research Institute, Department of Environmental Chemistry and Microbiology, Roskilde, Denmark.
| | | |
Collapse
|
18
|
Chung YK, Lam-Phua SG, Chua YT, Yatiman R. Evaluation of biological and chemical insecticide mixture against Aedes aegypti larvae and adults by thermal fogging in Singapore. MEDICAL AND VETERINARY ENTOMOLOGY 2001; 15:321-327. [PMID: 11583451 DOI: 10.1046/j.0269-283x.2001.00311.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
To improve the operational efficiency of dengue vector control in Singapore, larvicide and adulticide were applied together by thermal fog generator (Agrofog AF40). The mixture consisted of Bacillus thuringiensis var. israelensis (Vectobac 12 AS) as biological larvicide at 1.5 L/ha and pirimiphos-methyl (Actellic 50 EC) as adulticide at 100 g ai/ha, diluted 10-fold with water. Aerosol of this mixture was evaluated against the mosquito Aedes aegypti (L.) (Diptera: Culicidae) in bioassays using cages of 10 adult females exposed at heights of 0.3-2.4 m and distances of 3-12 m from the hand-held generator. Cups containing 200 mL water were treated at ground level by exposure to the aerosol application at the same distances from the generator. Subsequent larval bioassays on days 1, 7, 14, 21 and 28 post-spray involved exposing 20 larvae/cup for 48 h. Droplets had VMD 57 microm and female mosquitoes were killed by 2 s exposure to the aerosol at 3 m. We obtained 92-100% mortality of the adult mosquitoes and 100% control of larvae at 3 m distance, but only 10-13% mortality at 12 m from the fogger. In treated cups, larvae showed high mortality (92%) when exposed for 48 h even 1 month post-treatment. Results demonstrate the practical advantage of using this mixture of Vectobac 12AS and Actellic 50 EC for simultaneous control of Aedes adults and larvae, with prolonged larvicidal efficacy in treated containers.
Collapse
Affiliation(s)
- Y K Chung
- Vector Control & Research Department, Ministry of the Environment, Singapore.
| | | | | | | |
Collapse
|