The relevance of gene transfer to the safety of food and feed derived from genetically modified (GM) plants

Application of microbial agents in organic solid waste composting: a review

The rapid growth of organic solid waste has recently exacerbated environmental pollution problems, and its improper treatment has led to the loss of a large number of biomass resources. Here, we expound the advantages of microbial agents composting compared with conventional organic solid waste treatment technology, and review the important role of microbial agents composting in organic solid waste composting from the aspects of screening and identification, optimization of conditions, mechanism of action, combination with other technologies and ultra-high-temperature and ultra-low-temperature microbial composting. We discuss the value of microorganisms with different growth conditions in organic solid waste composting, and put forward a seasonal multi-temperature composite microbial composting technology. Provide new ideas for the all-round treatment of microbial agents in organic solid waste in the future. © 2024 Society of Chemical Industry.

Transformation of Rhodococcus Pigment Production Hydroxylase (PPH) gene into Camelina sativa: an alternative marker for the detection of transgenic plants

Abstract Production of transgenic plants with desired agronomic and horticultural traits has gained great importance to fulfill demands of the growing population. Genetic transformation is also a fundamental step to study basics of plant sciences. Different transformation protocols have been developed and used which are reliable and efficient. These protocols used antibiotic or herbicide resistance genes incorporated along with gene of interest to identify transformed plants from non-transformed ones. These marker genes may pose a threat to human and environment. Use of visual markers enables direct and easier observation of transformed plants with more precision. In current study a gene cassette with ‘pigment production hydroxylase (PPH) gene under fiber specific promoter (GhSCFP) and downstream Nos-terminator was designed. After checking the structural and functional efficiency of codon optimized gene using bioinformatics tools, the cassette was sent for chemical synthesis from commercial source. The pigment gene cassette (PPH_CEMB), cloned in pCAMBIA-1301, was transformed into Agrobacterium through electroporation. Agrobacterium-mediated floral dip method was used to transform Camelina sativa inflorescence. After seed setting a total of 600 seed were observed for change in color and out of these, 19 seeds developed a reddish-brown coloration, while the remaining 581 seeds remained yellow. The transformation efficiency calculated on basis of color change was 1.0%. PCR analysis of leaves obtained after sowing reddish seeds confirmed the transformation of pigment production gene, while no PCR amplification was observed in leaves of plants from wild type seeds. From the results it is evident that Agrobacterium-mediated transformation of C. sativa inflorescence is very efficient and environment friendly technique not only for detection of transformed plants but also to study basic cellular processes.

The impact of 'framing' in the adoption of GM crops

Genetically modified (GM) crops offer significant advantages in our crop improvement programs because they are created using a more targeted approach which is not possible in traditional breeding methods. Human benefit is one of the main objectives of crop improvement but the legal framework for the introduction of GM crops and the depiction and portrayal of GM crops in the media create barriers to these benefits. This article attempts to highlight the barriers to GM crop adoption particularly focusing on the idea of "framing" and the way GM technology is framed in the media. The resulting public health, economic, and ecological concerns about genetically modified plants, along with the reality of these misconceptions, are discussed with specific examples. Finally, we propose potential routes toward increased acceptance of GM crops.

Advances in Electrochemical Techniques for the Detection and Analysis of Genetically Modified Organisms: An Analysis Based on Bibliometrics

Since the first successful transgenic plants obtained in 1983, dozens of plants have been tested. On the one hand, genetically modified plants solve the problems of agricultural production. However, due to exogenous genes of transgenic plants, such as its seeds or pollen drift, diffusion between populations will likely lead to superweeds or affect the original traits. The detection technology of transgenic plants and their products have received considerable attention. Electrochemical sensing technology is a fast, low-cost, and portable analysis technology. This review interprets the application of electrochemical technology in the analysis and detection of transgenic products through bibliometrics. A total of 83 research articles were analyzed, spanning 2001 to 2021. We described the different stages in the development history of the subject and the contributions of countries and institutions to the topic. Although there were more annual publications in some years, there was no explosive growth in any period. The lack of breakthroughs in this technology is a significant factor in the lack of experts from other fields cross-examining the subject. Through keyword co-occurrence analysis, different research directions on this topic were discussed. The use of nanomaterials with excellent electrical conductivity allows for more sensitive detection of GM crops by electrochemical sensors. Furthermore, co-citation analysis was used to interpret the most popular reports on the topic. In the end, we predict the future development of this topic according to the analysis results.

Should we still worry about the safety of GMO foods? Why and why not? A review

Global population is increasing at an alarming rate, posing a threat on the supplies of basic needs and services. However, population increase does not seem to be a common agendum of the global scientists and political leaders. People in the developed countries are more concerned about new technologies and their products. Pseudo-threats related to the uncertainties of genetic engineering of crops and their outputs present on consumers are more audible and controversial than the real difficulties the world is experiencing at the moment and in the future. This review presents brief summaries of the real reasons to worry about and the uncertainties about genetically modified organisms. This article also presents the real uncertainties shared by consumers and scientists with respect to the past, present, and future of genetically engineered organisms. Developments in the field of precision genetics in the recent years and the implications on regulatory, breeding, and socio-cultural dimensions of the global settings are included.

Evaluation of resistance gene transfer from heat-treated Escherichia coli

Antimicrobial-resistant Escherichia coli may be present in various foods. The aim of this study was to evaluate the impact of heat treatment, simulating food preparation, on the possibility of antimicrobial resistance genes being transferred from E. coli cells. The study was performed on antimicrobial-resistant E. coli cells in suspension in a sterile saline solution. The stability of resistance genes and the possibility of their transfer by transformation or conjugation were analyzed. Results showed that antimicrobial-resistant E. coli cells managing to survive after a few minutes at 60 °C retained their antimicrobial resistance. No plasmid could be transferred by conjugation from antimicrobial-resistant E. coli cells heated to 60 °C for ten or more minutes. Twelve electroporation experiments were performed using a bacterial suspension heated to 70 °C for 30 min. Genes coding for resistance to extended-spectrum cephalosporins, tetracycline or sulfonamides were transferred to an E. coli DH5α recipient on two occasions. In conclusion we showed that heat-treated E. coli may occasionally transfer resistance genes.

Agrobacterium-mediated plant transformation: biology and applications

Plant genetic transformation heavily relies on the bacterial pathogen Agrobacterium tumefaciens as a powerful tool to deliver genes of interest into a host plant. Inside the plant nucleus, the transferred DNA is capable of integrating into the plant genome for inheritance to the next generation (i.e. stable transformation). Alternatively, the foreign DNA can transiently remain in the nucleus without integrating into the genome but still be transcribed to produce desirable gene products (i.e. transient transformation). From the discovery of A. tumefaciens to its wide application in plant biotechnology, numerous aspects of the interaction between A. tumefaciens and plants have been elucidated. This article aims to provide a comprehensive review of the biology and the applications of Agrobacterium-mediated plant transformation, which may be useful for both microbiologists and plant biologists who desire a better understanding of plant transformation, protein expression in plants, and plant-microbe interaction.

PCR-Based Method for the Detection of Toxic Mushrooms Causing Food-Poisoning Incidents

In this study, species-specific identification of five toxic mushrooms, Chlorophyllum molybdites, Gymnopilus junonius, Hypholoma fasciculare, Pleurocybella porrigens, and Tricholoma ustale, which have been involved in food-poisoning incidents in Japan, was investigated. Specific primer pairs targeting internal transcribed spacer (ITS) regions were designed for PCR detection. The specific amplicons were obtained from fresh, cooked, and simulated gastric fluid (SGF)-treated samples. No amplicons were detected from other mushrooms with similar morphology. Our method using one-step extraction of mushrooms allows rapid detection within 2.5 hr. It could be utilized for rapid identification or screening of toxic mushrooms.

Detection of dietary DNA, protein, and glyphosate in meat, milk, and eggs

Products such as meat, milk, and eggs from animals that have consumed genetically engineered (GE) feed are not currently subject to mandatory GE labeling requirements. Some voluntary "non-genetically modified organism" labeling has been associated with such products, indicating that the animals were not fed GE crops, as there are no commercialized GE food animals. This review summarizes the available scientific literature on the detection of dietary DNA and protein in animal products and briefly discusses the implications of mandatory GE labeling for products from animals that have consumed GE feed. Because glyphosate is used on some GE crops, the available studies on glyphosate residues in animal products are also reviewed. In GE crops, recombinant DNA (rDNA) makes up a small percentage of the plant's total DNA. The final amount of DNA in food/feed depends on many factors including the variable number and density of cells in the edible parts, the DNA-containing matrix, environmental conditions, and the specific transgenic event. Processing treatments and animals' digestive systems degrade DNA into small fragments. Available reports conclude that endogenous DNA and rDNA are processed in exactly the same way in the gastrointestinal tract and that they account for a very small proportion of food intake by weight. Small pieces of high copy number endogenous plant genes have occasionally been detected in meat and milk. Similarly sized pieces of rDNA have also been identified in meat, primarily fish, although detection is inconsistent. Dietary rDNA fragments have not been detected in chicken or quail eggs or in fresh milk from cows or goats. Collectively, studies have failed to identify full-length endogenous or rDNA transcripts or recombinant proteins in meat, milk, or eggs. Similarly, because mammals do not bioaccumulate glyphosate and it is rapidly excreted, negligible levels of glyphosate in cattle, pig and poultry meat, milk, and eggs have been reported. Despite consumer concern about the presence of trace concentrations of glyphosate that might have been applied to feed crops and/or the presence of rDNA or recombinant proteins in meat, milk, and eggs, the available data do not provide evidence to suggest that products from animals that have consumed approved GE feed crops differ in any distinguishable way from those derived from animals fed conventional feed or that products from animals fed GE feedstuffs pose novel health risks.

Proteome rebalancing in transgenic Camelina occurs within the enlarged proteome induced by β-carotene accumulation and storage protein suppression

Oilseed crops are global commodities for their oil and protein seed content. We have engineered the oilseed Camelina sativa to exhibit increased protein content with a slight decrease in oil content. The introduction of a phytoene synthase gene with an RNAi cassette directed to suppress the storage protein 2S albumin resulted in seeds with an 11-24 % elevation in overall protein. The phytoene synthase cassette alone produced enhanced β-carotene content of an average 275 ± 6.10 μg/g dry seed and an overall altered seed composition of 11 % less protein and comparable nontransgenic amounts of both oil and carbohydrates. Stacking an RNAi to suppress the major 2S storage protein resulted in seeds that contain elevated protein and slight decrease in oil and carbohydrate amounts showing that Camelina rebalances its proteome within an enlarged protein content genotype. In both β-carotene enhanced seeds with/without RNAi2S suppression, the seed size was noticeably enlarged compared to nontransgenic counterpart seeds. Metabolic analysis of maturing seeds indicate that the enhanced β-carotene trait had the larger effect than the RNAi2S suppression on the seed metabolome. The use of a GRAS (generally regarded as safe) β-carotene as a visual marker in a floral dip transformation system, such as Camelina, might eliminate the need for costly regulatory and controversial antibiotic resistance markers. β-carotene enhanced RNAi2S suppressed Camelina seeds could be further developed as a rapid heterologous protein production platform in a nonfood crop leveraging its enlarged protein content and visual marker.

Transgenic Crops and Sustainable Agriculture in the European Context

The rapid adoption of transgenic crops in the United States, Argentina, and Canada stands in strong contrast to the situation in the European Union (EU), where a de facto moratorium has been in place since 1998. This article reviews recent scientific literature relevant to the problematic introduction of transgenic crops in the EU to assess if there are specific reasons why transgenic crops have a potentially greater adverse impact on sustainable agriculture in the EU context than elsewhere. Sustainable agriculture integrates three main goals: environmental health, economic profitability, and socioeconomic equity. Transgenic crops do not appear a suitable tool for sustainable agriculture in the EU due to specific environmental, economic, and socioeconomic reasons. Therefore, a moratorium on transgenic crops based on the precautionary principle should be officially adopted until proper risk assessment. In addition, agroecological alternatives to transgenic crops fit better the EU vision of agriculture.

The Effects of GH Transgenic Goats on the Microflora of the Intestine, Feces and Surrounding Soil

The development of genetically engineered animals has brought with it increasing concerns about biosafety issues. We therefore evaluated the risks of growth hormone from transgenic goats, including the probability of horizontal gene transfer and the impact on the microbial community of the goats’ gastrointestinal tracts, feces and the surrounding soil. The results showed that neither the GH nor the neoR gene could be detected in the samples. Moreover, there was no significant change in the microbial community of the gastrointestinal tracts, feces and soil, as tested with PCR-denaturing gradient gel electrophoresis and 16S rDNA sequencing. Finally, phylogenetic analysis showed that the intestinal content, feces and soil samples all contained the same dominant group of bacteria. These results demonstrated that expression of goat growth hormone in the mammary of GH transgenic goat does not influence the microflora of the intestine, feces and surrounding soil.

Reducing blood glucose levels in TIDM mice with an orally administered extract of sericin from hIGF-I-transgenic silkworm cocoons

In previous studies, we reported that the blood glucose levels of mice with type I diabetes mellitus (TIDM) was reduced with orally administered silk gland powder from silkworms transgenic for human insulin-like growth factor-I (hIGF-I). However, potential safety hazards could not be eliminated because the transgenic silk gland powder contained heterologous DNA, including the green fluorescent protein (gfp) and neomycin resistance (neo) genes. These shortcomings might be overcome if the recombinant hIGF-I were secreted into the sericin layer of the cocoon. In this study, silkworm eggs were transfected with a novel piggyBac transposon vector, pigA3GFP-serHS-hIGF-I-neo, containing the neo, gfp, and hIGF-I genes controlled by the sericin-1 (ser-1) promoter with the signal peptide DNA sequence of the fibrin heavy chain (Fib-H) and a helper plasmid containing the piggyBac transposase sequence under the control of the Bombyx mori actin 3 (A3) promoter, using sperm-mediated gene transfer to generate the transformed silkworms. The hIGF-I content estimated by enzyme-linked immunosorbent assay was approximately 162.7 ng/g. To estimate the biological activity of the expressed hIGF-I, streptozotocin-induced TIDM mice were orally administered sericin from the transgenic silkworm. The blood glucose levels of the mice were significantly reduced, suggesting that the extract from the transgenic hIGF-I silkworm cocoons can be used as an orally administered drug.

Effects of genetically modified T2A-1 rice on the GI health of rats after 90-day supplement

Bacillus thuringiensis insecticidal toxin (Bt) rice will be commercialized as a main food source. Traditional safety assessments on genetically modified products pay little attention on gastrointestinal (GI) health. More data about GI health of Bt rice must be provided to dispel public' doubts about the potential effects on human health. We constructed an improved safety assessment animal model using a basic subchronic toxicity experiment, measuring a range of parameters including microflora composition, intestinal permeability, epithelial structure, fecal enzymes, bacterial activity, and intestinal immunity. Significant differences were found between rice-fed groups and AIN93G-fed control groups in several parameters, whereas no differences were observed between genetically modified and non-genetically modified groups. No adverse effects were found on GI health resulting from genetically modified T2A-1 rice. In conclusion, this study may offer a systematic safety assessment model for GM material with respect to the effects on GI health.

Antimicrobial resistance in the food chain: a review

Antimicrobial resistant zoonotic pathogens present on food constitute a direct risk to public health. Antimicrobial resistance genes in commensal or pathogenic strains form an indirect risk to public health, as they increase the gene pool from which pathogenic bacteria can pick up resistance traits. Food can be contaminated with antimicrobial resistant bacteria and/or antimicrobial resistance genes in several ways. A first way is the presence of antibiotic resistant bacteria on food selected by the use of antibiotics during agricultural production. A second route is the possible presence of resistance genes in bacteria that are intentionally added during the processing of food (starter cultures, probiotics, bioconserving microorganisms and bacteriophages). A last way is through cross-contamination with antimicrobial resistant bacteria during food processing. Raw food products can be consumed without having undergone prior processing or preservation and therefore hold a substantial risk for transfer of antimicrobial resistance to humans, as the eventually present resistant bacteria are not killed. As a consequence, transfer of antimicrobial resistance genes between bacteria after ingestion by humans may occur. Under minimal processing or preservation treatment conditions, sublethally damaged or stressed cells can be maintained in the food, inducing antimicrobial resistance build-up and enhancing the risk of resistance transfer. Food processes that kill bacteria in food products, decrease the risk of transmission of antimicrobial resistance.

Staphylococcus aureus Efb protein expression in Nicotiana tabacum and immune response to oral administration

Staphylococcus aureus (S. aureus) is one of the most widespread agent of diseases in humans and animals. In dairy cows, S. aureus is the most frequently isolated contagious pathogens in mastitis cases and vaccines are one of the potential tools to control the infections, thus decreasing the use of antibiotics. Among all the virulence factors produced by S. aureus, extra cellular fibrinogen binding protein (Efb) is an important one in the pathogenesis of mastitis. Plants are useful bioreactors to produce antigens and the aim of the study was the production of Efb in two cultivars of Nicotiana tabacum as a mean to produce vaccine against S. aureus in plants. A matrix attachment region (MAR) sequence was inserted near the two borders of transfer-DNA in the transformation vector in the two possible orientations. The presence of MAR elements in the transformation system significantly improved transformation efficiency and Efb protein yield up to a 2% level on total soluble protein (TSP). Mice orally immunized with transgenic lyophilized leaves produced an antigen-specific immune response.

A survey of drug resistance bla genes originating from synthetic plasmid vectors in six Chinese rivers

Antibiotic resistance poses a significant challenge to human health and its rate continues to rise globally. While antibiotic-selectable synthetic plasmid vectors have proved invaluable tools of genetic engineering, this class of artificial recombinant DNA sequences with high expression of antibiotic resistance genes presents an unknown risk beyond the laboratory setting. Contamination of environmental microbes with synthetic plasmid vector-sourced antibiotic resistance genes may represent a yet unrecognized source of antibiotic resistance. In this study, PCR and real-time quantitative PCR were used to investigate the synthetic plasmid vector-originated ampicillin resistance gene, β-lactam antibiotic (blá), in microbes from six Chinese rivers with significant human interactions. Various levels of blá were detected in all six rivers, with the highest levels in the Pearl and Haihe rivers. To validate the blá pollution, environmental plasmids in the river samples were captured by the E. coli transformants from the community plasmid metagenome. The resultant plasmid library of 205 ampicillin-resistant E. coli (transformants) showed a blá-positive rate of 27.3% by PCR. Sequencing results confirmed the synthetic plasmid vector sources. In addition, results of the Kirby-Bauer disc-diffusion test reinforced the ampicillin-resistant functions of the environmental plasmids. The resistance spectrum of transformants from the Pearl and Haihe rivers, in particular, had expanded to the third- and fourth-generation of cephalosporin drugs, while that of other transformants mainly involved first- and second-generation cephalosporins. This study not only reveals environmental contamination of synthetic plasmid vector-sourced blá drug resistance genes in Chinese rivers, but also suggests that synthetic plasmid vectors may represent a source of antibiotic resistance in humans.

Impacts of human lysozyme transgene on the microflora of pig feces and the surrounding soil

The rapid development of genetic engineering and extensive applications of genetically engineered (GE) animals have provided many research benefits, but concerns have been raised over the potential environmental impact of transgenic animals. We investigated the effects of human lysozyme (hLZ) transgenic pigs which can express hLZ in their mammary glands on the surrounding environment from the angle of the changes of pig feces and the surrounding soil, including the probability of horizontal gene transfer (HGT), the impact on microbial communities in pig gastrointestinal (GI) tracts and soil, and the influence on the total nitrogen (TN) and total phosphorus (TP) content of pig excrement and surrounding soil. Results showed that hLZ gene was not detected by polymerase chain reaction (PCR) or quantitative real-time PCR (Q-PCR) in gut microbial DNA extracts of manure or microbial DNA extracts of topsoil. PCR-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) analysis and 16S rDNA sequence analysis showed that hLZ gene had no impact on the microflora structure of pig guts or soil. Finally, TN and TP contents were not significantly different in pig manure or soils taken at different distances from the pig site (P>0.25).

Do genetically modified crops affect animal reproduction? A review of the ongoing debate

In the past few years, genetically modified (GM) crops aimed at producing food/feed that became part of the regular agriculture in many areas of the world. However, we are uncertain whether GM food and feed can exert potential adverse effects on humans or animals. Of importance, the reproductive toxicology of GM crops has been studied using a number of methods, and by feeding GM crops to a number species of animals to ensure the safety assessment of GM food and feed. It appears that there are no adverse effects of GM crops on many species of animals in acute and short-term feeding studies, but serious debates of effects of long-term and multigenerational feeding studies remain. The aims of this review are to focus on the latest (last 3 to 4 years) findings and debates on reproduction of male and female animals after feeding daily diets containing the GM crops, and to present the possible mechanism(s) to explain their influences.

Multiplex real-time PCR assay for simultaneous detection of Omphalotus guepiniformis and Lentinula edodes

A rapid multiplex real-time PCR assay was developed to achieve highly specific, simultaneous detection of two kinds of mushrooms, Omphalotus guepiniformis and Lentinula edodes. Primers and TaqMan minor groove binder probes were designed according to the internal transcribed spacers 1-5.8S region of rDNA and evaluated by the specificity for fruiting bodies of 17 O. guepiniformis, 16 L. edodes and samples from 57 other species. DNA extracts of all the target species had positive signals with no cross-reaction, the limit of detection being 0.00025 ng of DNA. Threshold cycle (Ct) values for raw and processed fruiting bodies and for fruiting bodies (1% (w/w)) mixed with foodstuffs or artificial gastric juice contents ranged from 17.16 to 26.60 for both examined species. This new assay proved specific to the target species, highly sensitive, and applicable to processed food samples and gastric juice contents, making it useful for rapidly identifying O. guepiniformis and L. edodes.

Comparison of three DNA extraction methods for feed products and four amplification methods for the 5'-junction fragment of Roundup Ready soybean

Three methods of DNA extraction from feed products and four detection methods for the 5'-junction fragment of genetically modified (GM) Roundup Ready soybean (RRS) were compared and evaluated. The DNA extraction methods, including cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and guanidine hydrochloride (Kit), were assessed for their yields and purity of DNA, extraction time, and reagent cost. The DNA yields of CTAB, SDS, and Kit were 52-694, 164-1750 and 23-105 ng/mg sample, and their extraction time was 2.5-3, 2-2.5, and 1.5-2 h with reagent cost about US dollar 0.24, 0.13, and 1.9 per extraction, respectively. The SDS method was generally well suited to all kinds of feed matrices tested. The limits of detection for the four amplification protocols, including loop-mediated isothermal amplification (LAMP), hyperbranched rolling circle amplification (HRCA), conventional polymerase chain reaction (PCR), and real-time PCR, were 48.5, 4.85, 485, and 9 copies of the pTLH10 plasmid, respectively. The ranked results of the four detection methods were based on multiattribute utility theory as follows (from best to worse): HRCA, LAMP, PCR, and real-time PCR. This comparative evaluation was specifically useful for selection of a highly efficient DNA extraction or amplification method for detecting different GM ingredients.

Approaches for gene targeting and targeted gene expression in plants

Transgenic science and technology are fundamental to state-of-the-art plant molecular genetics and crop improvement. The new generation of technology endeavors to introduce genes 'stably' into 'site-specific' locations and in 'single copy' without the integration of extraneous vector 'backbone' sequences or selectable markers and with a 'predictable and consistent' expression. Several similar strategies and technologies, which can push the development of 'smart' genetically modified plants with desirable attributes, as well as enhance their consumer acceptability, are discussed in this review.

Catecholamines increase conjugative gene transfer between enteric bacteria

The ability of pathogenic bacteria to sense and respond to periods of host stress is critical to their lifestyle. Adrenaline and norepinephrine are catecholamines that mediate acute host stress in vertebrates and invertebrates. Catecholamines are also used as environmental cues to enhance growth, motility and virulence of bacterial pathogens via specific binding receptors. Incidence of multidrug resistant and highly virulent bacterial pathogens is on the rise, and majority of the genes for antimicrobial resistance (AMR) and virulence are carried on horizontally transferable genetic elements. Conjugation machinery offers an efficient method for acquisition of AMR and virulence genes, which may be responsible for propelling the evolution of pathogenic bacteria. Here we show that norepinephrine (NE) at physiological concentrations enhances horizontal gene transfer (HGT) efficiencies of a conjugative plasmid from a clinical strain of Salmonella Typhimurium to an Escherichia coli recipient in vitro. Expressions of plasmid encoded transfer (tra) genes necessary for conjugation were also significantly upregulated in the presence of NE. Phentolamine, an α-adrenergic receptor antagonist, negated the effects of NE on conjugation more strongly than propranolol, a β-adrenergic receptor antagonist. This study for the first time provides evidence that innate mediators of acute host stress may influence evolution and adaptation of bacterial pathogens.

Assessment of bacterial antibiotic resistance transfer in the gut

We assessed horizontal gene transfer between bacteria in the gastrointestinal (GI) tract. During the last decades, the emergence of antibiotic resistant strains and treatment failures of bacterial infections have increased the public awareness of antibiotic usage. The use of broad spectrum antibiotics creates a selective pressure on the bacterial flora, thus increasing the emergence of multiresistant bacteria, which results in a vicious circle of treatments and emergence of new antibiotic resistant bacteria. The human gastrointestinal tract is a massive reservoir of bacteria with a potential for both receiving and transferring antibiotic resistance genes. The increased use of fermented food products and probiotics, as food supplements and health promoting products containing massive amounts of bacteria acting as either donors and/or recipients of antibiotic resistance genes in the human GI tract, also contributes to the emergence of antibiotic resistant strains. This paper deals with the assessment of antibiotic resistance gene transfer occurring in the gut.

Health considerations regarding horizontal transfer of microbial transgenes present in genetically modified crops

The potential effects of horizontal gene transfer on human health are an important item in the safety assessment of genetically modified organisms. Horizontal gene transfer from genetically modified crops to gut microflora most likely occurs with transgenes of microbial origin. The characteristics of microbial transgenes other than antibiotic-resistance genes in market-approved genetically modified crops are reviewed. These characteristics include the microbial source, natural function, function in genetically modified crops, natural prevalence, geographical distribution, similarity to other microbial genes, known horizontal transfer activity, selective conditions and environments for horizontally transferred genes, and potential contribution to pathogenicity and virulence in humans and animals. The assessment of this set of data for each of the microbial genes reviewed does not give rise to health concerns. We recommend including the above-mentioned items into the premarket safety assessment of genetically modified crops carrying transgenes other than those reviewed in the present study.

Lack of detectable DNA uptake by transformation of selected recipients in mono-associated rats

Background

An important concern revealed in the public discussion of the use of genetically modified (GM) plants for human consumption, is the potential transfer of DNA from these plants to bacteria present in the gastrointestinal tract. Especially, there is a concern that antibiotic resistance genes used for the construction of GM plants end up in pathogenic bacteria, eventually leading to untreatable disease.

Findings

Three different bacterial species (Escherichia coli, Bacillus subtilis, Streptococcus gordonii), all natural inhabitants of the food and intestinal tract environment were used as recipients for uptake of DNA. As source of DNA both plasmid and genomic DNA from GM plants were used in in vitro and in vivo transformation studies. Mono-associated rats, creating a worst-case scenario, did not give rise to any detectable transfer of DNA.

Conclusion

Although we were unable to detect any transformation events in our experiment, it cannot be ruled out that this could happen in the GI tract. However, since several steps are required before expression of plant-derived DNA in intestinal bacteria, we believe this is unlikely, and antibiotic resistance development in this environment is more in danger by the massive use of antibiotics than the consumption of GM food harbouring antibiotic resistance genes.

Diagnostic microarray for human and animal bacterial diseases and their virulence and antimicrobial resistance genes

Rapid diagnosis and treatment of disease is often based on the identification and characterization of causative agents derived from phenotypic characteristics. Current methods can be laborious and time-consuming, often requiring many skilled personnel and a large amount of lab space. The objective of our study was to develop a spotted microarray for rapid identification and characterization of bacterial pathogens and their antimicrobial resistance genes. Our spotted microarray consists of 489 70mer probes that detect 40 bacterial pathogens of medical, veterinary and zoonotic importance (including 15 NIAID Category A, B and C pathogens); associated genes that encode resistance for antimicrobial and metal resistance; and DNA elements that are important for horizontal gene transfer among bacteria. High specificity and reliability of the microarray was achieved for bacterial pathogens of animal and human importance by validating MDR pathogenic bacteria as pure cultures or by following their inoculation in complex and highly organic sample matrices, such as soil and manure.

Facts and fiction of genetically engineered food

The generation of genetically engineered (GE) foods has been raising several concerns and controversies that divide not only the general public but also the scientific community. The fear and importance of the new technology, as well as commercial interests, have supported many of the ongoing discussions. The recent increase in the number of GE foods approved for import into the European Union and the increasingly global commercial food trades justify revisiting the facts and fiction surrounding this technology with the aim of increasing public awareness for well-informed decisions. Techniques that have recently become available for assessing food quality and its impact on human health, as well as the wealth of scientific data previously generated, clearly support the safety of commercialized GE products.