Foodborne Microbes Research Articles

Young People’s Views on Food Hygiene and Food Safety: A Multicentre Qualitative Study

Foodborne diseases are a global burden, are preventable, and young people are a key population for behaviour change as they gain autonomy. This study aimed to explore young people’s needs across several European countries in relation to learning about and implementing food hygiene and food safety. Qualitative focus groups and interviews were conducted in rural and city regions across England, France, Hungary and Portugal. Data were collected to attain data saturation, transcribed, thematically analysed, and mapped to the Theoretical Domains Framework. Twenty-five out of 84 schools approached (29.8%) participated, with data collected from 156 11–18-year-old students. Students had good knowledge of personal hygiene but did not always follow hygiene rules due to forgetfulness, lack of facilities or lack of concern for consequences. Students had limited understanding of foodborne microbes, underestimated the risks and consequences of foodborne illness and perceived the “home” environment as the safest. Young people preferred interactive educational methods. Addressing gaps in young people’s food safety knowledge is essential to improve their lack of concern towards foodborne illness and motivate them to follow food hygiene and safety behaviours consistently. Findings have been used to develop educational resources to address gaps in knowledge, skills, attitudes and beliefs.

Nanobody-based immunosensing methods for safeguarding public health.

Immunosensing methods are biosensing techniques based on specific recognition of an antigen–antibody immunocomplex, which have become commonly used in safeguarding public health. Taking advantage of antibody-related biotechnological advances, the utilization of an antigen-binding fragment of a heavy-chain-only antibody termed as 'nanobody' holds significant biomedical potential. Compared with the conventional full-length antibody, a single-domain nanobody retaining cognate antigen specificity possesses remarkable physicochemical stability and structural adaptability, which enables a flexible and efficient molecular design of the immunosensing strategy. This minireview aims to summarize the recent progress in immunosensing methods using nanobody targeting tumor markers, environmental pollutants, and foodborne microbes.

Production and antimicrobial activity of trans-resveratrol, trans-arachidin-1 and trans-arachidin-3 from elicited peanut hairy root cultures in shake flasks compared with bioreactors

Obtaining large-scale hairy root cultures is a major challenge to increasing root biomass and secondary metabolite production. Enhanced production of stilbene compounds such as trans-resveratrol, trans-arachidin-1 and trans-arachidin-3 was achieved using an elicitor treatment procedure. Two different hairy root inoculum densities were investigated and compared between shake flask and bioreactor cultures. The lowest growth index was observed using a 20 g/L inoculum size in the bioreactor, which differed significantly from bioreactor of 5 g/L. Increasing the hairy root inoculum size from 5 g/L to 20 g/L in both the shake flask and bioreactor significantly improve antioxidant activity, phenolic content and stilbene compound levels. The highest ABTS and FRAP antioxidant activity, and levels of total phenolic compounds, trans-arachidin-1 and trans-arachidin-3 in the crude extract were demonstrated in shake flask cultures with a 20 g/L inoculum after elicitation for 72 h. The minimum inhibitory concentrations (MICs) of the crude extract to inhibit growth of foodborne microbes, S. aureus, S. typhimurium and E. coli, were 187.5, 250 and 500 μg/mL, respectively. This was due to the ability of the crude extract to disrupt the cell membrane, as observed by scanning electron microscopy (SEM) showing ruptured pores on the S. aureus and S. typhimurium cell surfaces. Moreover, the E. coli cell division process could be inhibited by the crude extract, which promoted an increase in cell size. A DNA nicking assay indicated that a 50 μg/mL concentration of the crude extract caused plasmid DNA damage that might be due to a genotoxic effect of the pro-oxidant activity of the crude extract.

Retaining the ‘essence’ of essential oil: Nanoemulsions of citral and carvone reduced oil loss and enhanced antibacterial efficacy via bacterial membrane perturbation

Essential oils (EO), which can be extracted from different edible, therapeutic and herbal plants, have been well known as natural antimicrobial additives. However, it is usually hard to attain high antimicrobial efficacy of these EOs, when these are used in different combinations for the control of foodborne microbes, because of their low solubility in water and interactive binding. Here, we report an optimized oil-in-water (o/w) nanoemulsification process for citral and carvone which generated mean droplet size of 11–19 nm. It was found that nature of surfactant viz., Brij-58 vs leaf extract of Lantana camara (LC) plays crucial role in determining the overall stability and size of the droplets. The screened nanoemulsions (NEs), when stored for long duration, showed minimal decrease in oil content with retention of antioxidant activity. The prepared NEs documented enhanced antibacterial activity compared to pure oils whereas higher degree of killing was observed towards Pseudomonas aeruginosa. The NEs also showed killing of both the bacteria on wound dressing cotton gauze bandages (GB). The outcome of the present study may be used for the development of safe and biocompatible antibacterial agents.

Development of antiviral and bacteriostatic chitosan-based food packaging material with grape seed extract for murine norovirus, Escherichia coli and Listeria innocua control.

Edible coatings and films based on chitosan, and containing grape seed extract (GSE), were developed and their activities tested against murine norovirus (MNV‐1), Listeria innocua and Escherichia coli K12. Grape seed extract concentrations of 1%, 1.5%, and 2.5% dissolved in deionized water resulted in MNV‐1 plaque reductions (p < .05) of 1.75, 2.60, and 3.58 log PFU/ml, respectively after 3 hr. Two percent (w/w) chitosan solutions incorporated with 2.5% and 5% GSE also significantly (p < .05) reduced MNV‐1 titers by 2.68 and 4.00 log PFU/ml, respectively after 3 hr. Additionally, incorporation of the GSE into the chitosan films also showed antimicrobial efficacy against MNV‐1, L. innocua, and E. coli K12. Chitosan films containing 5%, 10%, and 15% GSE caused MNV‐1 reductions of 0.92, 1.89, and 2.27 log PFU/ml, respectively, after 4 hr of incubation. Also, after 24 hr, the 5% and 10% GSE films reduced MNV‐1 titers by 1.90 and 3.26 log PFU/ml, respectively, while the 15% GSE film reduced MNV‐1 to undetectable levels. For E. coli K12, there were reductions of 2.28, 5.18, and 7.14 log CFU/ml after 24 hr exposure by the 5%, 10%, and 15% GSE films, respectively. Also, L. innocua counts were reduced by 3.06, 6.15, and 6.91 log CFU/ml by the 5%, 10%, and 15% GSE films, respectively. This study demonstrated that GSE in edible films and coatings is effective against the organisms tested, and this shows that they are effective against foodborne microbes of public health concerns.

TLC bioautography-guided isolation of essential oil components of cinnamon and clove and assessment of their antimicrobial and antioxidant potential in combination.

This study aimed to evaluate possible synergistic interactions on antimicrobial and antioxidant efficacy of clove and cinnamon oil components in combination and characterization of compounds responsible for synergistic interactions using TLC bioautography followed by checkerboard titration, isobologram analysis, and spectrometric characterization. Among the combinations tested, cinnamaldehyde from cinnamon oil and eugenol from clove oil in combination showed a synergistic antimicrobial interaction against foodborne microbes Listeria monocytogenes (fractional inhibitory concentration index (FICI): 0.31), Salmonella typhimurium (FICI: 0.41), and Aspergillus niger (FICI: 0.48), and synergistic antioxidant efficacy (combination index: 0.78) in in vitro model. Cinnamaldehyde/eugenol blend did not show any cytotoxic effect (IC50 > 1000 μg/ml) in human normal keratinocyte cell line. The results provide evidence that the cinnamaldehyde/eugenol blend may help in designing a more potent novel natural antimicrobial and antioxidant agent in food and pharmaceutical industries.

DNA sequencing, genomes and genetic markers of microbes on fruits and vegetables.

SummaryThe development of DNA sequencing technology has provided an effective method for studying foodborne and phytopathogenic microorganisms on fruits and vegetables (F & V). DNA sequencing has successfully proceeded through three generations, including the tens of operating platforms. These advances have significantly promoted microbial whole‐genome sequencing (WGS) and DNA polymorphism research. Based on genomic and regional polymorphisms, genetic markers have been widely obtained. These molecular markers are used as targets for PCR or chip analyses to detect microbes at the genetic level. Furthermore, metagenomic analyses conducted by sequencing the hypervariable regions of ribosomal DNA (rDNA) have revealed comprehensive microbial communities in various studies on F & V. This review highlights the basic principles of three generations of DNA sequencing, and summarizes the WGS studies of and available DNA markers for major bacterial foodborne pathogens and phytopathogenic fungi found on F & V. In addition, rDNA sequencing‐based bacterial and fungal metagenomics are summarized under three topics. These findings deepen the understanding of DNA sequencing and its application in studies of foodborne and phytopathogenic microbes and shed light on strategies for the monitoring of F & V microbes and quality control.

Feasibility of Determination of Foodborne Microbe Contamination of Fresh-Cut Shredded Cabbage Using SW-NIR

Shredded cabbage is widely used in much ready-to-eat food. Therefore, rapid methods for detecting and monitoring the contamination of foodborne microbes is essential. Short wavelength near infrared (SW-NIR) spectroscopy was applied on two types of solutions, a drained solution from the outer surface of the shredded cabbage (SC) and a ground solution of shredded cabbage (GC) which were inoculated with a mixture of two bacterial suspensions, Escherichia coli and Salmonella typhimurium. NIR spectra of around 700 to 1100 nm were collected from the samples after 0, 4, and 8 h at 37 °C incubation, along with the growth of total bacteria, E. coli and S. typhimurium. The raw spectra were obtained from both sample types, clearly separated with the increase of incubation time. The first derivative, a Savitzky–Golay pretreatment, was applied on the GC spectra, while the second derivative was applied on the SC spectra before developing the calibration equation, using partial least squares regression (PLS). The obtained correlation (r) of the SC spectra was higher than the GC spectra, while the standard error of cross-validation (SECV) was lower. The ratio of prediction of deviation (RPD) of the SC spectra was higher than the GC spectra, especially in total bacteria, quite normal for the E. coli but relatively low for the S. typhimurium. The prediction results of microbial spoilage were more reliable on the SC than on the GC spectra. Total bacterial detection was best for quantitative measurement, as E. coli contamination could only be distinguished between high and low values. Conversely, S. typhimurium predictions were not optimal for either sample type. The SW-NIR shows the feasibility for detecting the existence of microbes in the solution obtained from SC, but for a more specific application for discrimination or quantitation is needed, proving further research in still required.

Effect of annealing temperature on the morphology and antibacterial activity of Mg-doped zinc oxide nanorods

Herein, magnesium-doped zinc oxide nanorods (MgZnO NRs) were synthesized by the co-precipitation method and annealed at different temperatures in the range of 100–500 °C. The increase in the annealing temperature was found to influence both chemical and morphological structures of the MgZnO NRs: Ultraviolet–visible diffuse reflectance spectroscopy showed an increase in band gap with increase in the annealing temperature. Fourier-transform infrared spectra showed that two characteristic peaks at 487 cm−1 and 442 cm−1 corresponding to a weak Zn–O stretching initially decreased and then disappeared with increase in the annealing temperature. Moreover, the MgZnO NRs annealed at 100 °C had large crystallite size, high aspect ratio, and narrow edges. Remarkably, the MgZnO NRs annealed at 100 °C exhibited the highest antibacterial activity against both S. aureus and E. coli strains, attributed to the high aspect ratio and diffusion ability of the Zn2+ ions and large surface charge, crystallite size, and surface area. The MgZnO NRs annealed at the relatively low temperature of 100 °C could be easily produced commercially, in large quantities, and effectively used to prevent the growth of foodborne microbes in food packaging applications.

Essential Oil Nanoemulsions and their Antimicrobial and Food Applications

The consumer awareness for secure insignificantly handled food has constrained the food dealers either to decrease the measure of chemically synthetic antimicrobial substances or to replace them with natural ones. Essential oils (EO) extracted from edible, therapeutic and herbal plants have been well recognized as natural antimicrobial additives. As characteristic then viable antimicrobials, EO have been progressively observed towards control of foodborne microbes and progression of nourishment wellbeing. It is ordinarily hard to achieve high antimicrobial vulnerability when mixing with EO in nourishment based items because of low dissolvability of water and interactive binding. Subsequently, the delivery system of nanoemulsion-based EO is emerging as aviable solution to control the growth of foodborne pathogens. Lipophilic compounds are distributed uniformly in the aqueous phase with the help of nanoemulsion technique. Therefore, the nanoemulsion formulation is generally comprised of mainly three constituents i.e. oil phase, aqueous and a surfactant. Nanoemulsions droplet average diameters should below 100 nm. According to previous studies, the clove, cinnamon and thyme oil nanoemulsions which were formulated with non ionic surfactants (Spans and Tweens) were having droplet size less than 100nm. The current review emphases on essential oil based nanoemulsions which are prepared with different ingredients which hence, enhance the antimicrobial action in food items.

Probiotics and plant-derived compounds as eco-friendly agents to inhibit microbial toxins in poultry feed: a comprehensive review.

Some of pathogenic bacteria and fungi have the ability to produce fetal toxins which may be the direct causes of cytotoxicity or cellular dysfunction in the colonization site. Biological and non-biological environmental factors, challenge and microbes influence the effect of toxins on these pathogens. Modern research mentions that many natural materials can reduce the production of toxins in pathogenic microbes. However, researches that explain the mechanical theories of their effects are meager. This review aimed to discuss the ameliorative potential role of plant-derived compounds and probiotics to reduce the toxin production of food-borne microbes either in poultry bodies or poultry feedstuff. Moreover, studies that highlight their own toxicological mechanisms have been discussed. Adding natural additives to feed has a clear positive effect on the enzymatic and microbiological appearance of the small intestine without any adverse effect on the liver. Studies in this respect were proposed to clarify the effects of these natural additives for feed. In conclusion, it could be suggested that the incorporation of probiotics, herbal extracts, and herbs in the poultry diets has some beneficial effects on productive performance, without a positive impact on economic efficiency. In addition, the use of these natural additives in feed has a useful impact on the microbiological appearance of the small intestine and do not have any adverse impacts on intestinal absorption or liver activity as evidenced by histological examination.

Hygiene Hypothesis: What Is the Current Thinking?

Our aim was to discuss the hygiene hypothesis and current thinking about it. Hygiene hypothesis suggests that an underlying reason for the recent prominent rise in allergic diseases may be linked with the diminution of the incidence of early childhood infections, which can be transmitted by means of contact with older siblings. Hygiene hypothesis suggests that contact with microbes in the environment in early life through pets, unpasteurized food, and nonsterilized water may protect from atopic diseases. Exposure to microbial pathogens and animals in infancy prevents atopy by Th1-like cytokine responses or by modifying Th2-like immune responses. Chronic infection and inflammation may protect against atopic disease. Alteration of exposure to microorganisms and access to clean water as well as issues related with food, sanitation, medical and obstetric practices, and urban lifestyle may have significant roles. Decreased exposure to bacteria in the early infancy period may shift the immune system to a predominantly Th2 state which is detected in atopic cases. Environmental exposure may lead to epigenetic changes which causes a shift of immune reactions against microorganisms. The hygiene hypothesis implies that modern living conditions can be responsible for the rise in the incidences of allergic disease and asthma. Protective effect of food-borne microbes on allergic diseases is another remarkable issue.

Preparation of chitosan-TiO2 composite film with efficient antimicrobial activities under visible light for food packaging applications

By incorporation of TiO2 nano-powder in chitosan, a chitosan-TiO2 composite film was prepared with efficient antimicrobial activity against food-borne pathogenic microbes and expected to be a promising food packaging material. Scanning electron microscopy analysis showed that the TiO2 nano-powder was successfully and uniformly dispersed into the chitosan matrix. TiO2 addition led to enhanced hydrophilicity, to better mechanical properties, and to decreased light transmittance in visible light region of the composite film. The chitosan-TiO2 film possessed efficient antimicrobial activity against four tested strains, i.e. Escherichia coli, Staphylococcus aureus, Candida albicans, and Aspergillus niger with 100% sterilization in 12h. It moreover provoked the leakage of cellular substances through damaged membrane. The prepared chitosan-TiO2 film was tested for packaging red grapes to prevent microbial infection and extend their shelf life. Results were positive, stressing the potential of the novel bio-nano composite film for food packaging applications.

Inhibitory effect of novel thioflavone derivatives against foodborne and spoilage microbes on fresh fruit

AbstractIn this study, the antimicrobial activities of four thioflavones against foodborne and food spoilage bacteria (Three Gram‐positive and Five Gram‐negative bacteria) and one fungus were assessed. Antimicrobial effects of the thioflavones were evaluated using broth micro‐dilution and agar dilution assays. We generated survival curves based on the kinetics of bacterial inactivation after 24 hr of thioflavone exposure. The minimum inhibitory concentrations (MIC) for the microorganisms tested were 8–120 μg/mL. The minimum bactericidal concentrations (MBC) were 60–120 μg/mL. We evaluated three novel thioflavone derivatives and found that they exhibited strong antimicrobial activities against most of the microorganisms tested. In an in vivo antifungal study, thioflavone treatments reduced fungal decay, and 4'‐chloro‐thioflavone at a concentration of 120 μg/mL showed complete control of Rhizopus sp. in wound‐inoculated fruit.Practical applicationsThere is an urgent need for the development of new classes of antimicrobial compounds and the new thioflavone derivatives represent such a development. Thioflavones are sulfur‐containing flavones that inhibit the growth of foodborne pathogens and food spoilage microorganisms. Foodborne spoilage by bacteria or fungi cause postharvest decay and rapid deterioration, which affects the quality and shortens the shelf life of fruits and vegetables. We believe that these new thioflavone derivatives provide a viable alternative as a food preservative can extend shelf life of fruits and vegetables.

Advancements in Microarray Utility for Detection and Tracking of Foodborne Microbes in the Genomic Era

Outbreaks caused by foodborne microbes pose serious public health and food safety concerns worldwide. There is a great demand for rapid, sensitive and high-throughput methods to detect and track these pathogens in food, water and other environments. Recent advances in DNA genomic technology have enabled high-throughput analyses of strains by capturing total genomic content of strains and with concomitant comparative phylogenies. Microarrays are particularly adept for distilling large amounts of genomic DNA sequence information such as the gene(s) or genetic traits of hundreds of foodborne isolates in a single experiment. Hence, over the past two decades, microarray technology has advanced tremendously due to accessibility to thousands of complete and draft microbial genomes and this progress has led to the design and manufacturing of newer microarrays which can now identify gene sequence variations down to a single nucleotide polymorphism. DNA microarray remains a useful tool for rapid and refined genomic analysis of foodborne microbes. In this review, we will primarily focus our discussion on pathogen detection, serotype identification and tracking the genetic diversity and source of contamination of respective foodborne strains with our first-hand experience in using this technology.

The Impacts of Climate Change on Food Poisoning Cases in Malaysia

Introduction: Malaysia is a tropical country, and the climate is hot and humid throughout the year, which is suitable for the growth of the foodborne microbes. This study is an attempt to quantify climate-induced increases in morbidity rates of food poisoning cases. Methodology: Monthly food poisoning cases and average monthly meteorological data from 2004 to 2014 were obtained from the Malaysian Ministry of Health and Malaysian Meteorological Department, respectively. Population projections in Malaysia, up to the year 2040 were adopted from the Malaysian Department of Statistics and modified to the year 2100 based on the mean percentage increase of 40 years. The PRECIS model was used to project future climate up to the year 2100 under the A1B scenario. Poisson generalized linear models were developed to quantify the relationship between climatic parameters and the number of reported food poisoning cases in the future. Result: The findings revealed that the total number of food poisoning cases in Malaysia during the 11 years of study period was 134,818 cases with 46 deaths. The mean age of the patients was 20±18 years old. Some 52.8% of the cases were among the ages of 13-24 years old, followed by 25.3% and 21.6% among the ages of 25-59 years old and below than 12 years old, respectively. Among the cases, 97.2% were Malaysians and 55.7% were females. Temperature, precipitation and relative humidity gave a significant impact on food poisoning cases in Kelantan and Melaka (p&lt;0.005), while in Pahang and Sabah, only disease trend was significant (p&lt;0.005). E.coli was associated with food poisoning cases in 2 states which were in Johor and Sabah (p&lt;0.005). Projected percentage increase in food poisoning cases per month up to the year 2100 under A1B scenario in Kelantan, Melaka, Pahang and Sabah were 36.5%, 51.0%, 18.0% and 45.9%, respectively. Conclusion: The study concludes that climate does affect the distribution of food poisoning cases in certain states in Malaysia.

Biological and quantitative-SAR evaluations, and docking studies of (E)-N -benzylidenebenzohydrazide analogues as potential antibacterial agents.

A series of 15 (E)-N'-benzylidenebenzohydrazide analogues were evaluated for their antimicrobial activities against eleven pathogenic and food-borne microbes, namely, S. aureus (G+), L. monocytogenes (G+), B. subtilis (G+), K. pneumonia (G¯), C. sakazakii (G¯), C. freundii (G¯), S. enterica (G¯), S. enteritidis (G¯), E. coli (G¯), Y. pestis (G¯), and P. aeruginosa (G¯). Most of the compounds exhibited selective activity against some Gram-negative bacterial strains. Of the compounds tested (3a-o), 3b and 3g were most active against C. freundii (MIC = ~19 µg mL-1). Whereas, compounds 3d, 3i, 3k and 3n exhibited MIC values ranging from 37.5 to 75 μg mL-1 against C. freundii, and compounds 3e, 3l and 3n had MIC values of ~75 μg mL-1 against K. pneumonia. Quantitative structure-antibacterial activity relationships were studied using physicochemical parameters and a good correlation was found between calculated octanol-water partition coefficients (clogP; a lipophilic parameter) and antibacterial activities. In silico screening was also performed by docking high (3b and 3g) and low (3n) activity compounds on the active site of E. coli FabH receptor, which is an important therapeutic target. The findings of these in silico screening studies provide a theoretical basis for the design and synthesis of novel benzylidenebenzohydrazide analogues that inhibit bacterial FabH.

Ecological robustness of the gut microbiota in response to ingestion of transient food-borne microbes.

Resident gut microbes co-exist with transient bacteria to form the gut microbiota. Despite increasing evidence suggesting a role for transient microbes on gut microbiota function, the interplay between resident and transient members of this microbial community is poorly defined. We aimed to determine the extent to which a host's autochthonous gut microbiota influences niche permissivity to transient bacteria using a fermented milk product (FMP) as a vehicle for five food-borne bacterial strains. Using conventional and gnotobiotic rats and gut microbiome analyses (16S rRNA genes pyrosequencing and reverse transcription qPCR), we demonstrated that the clearance kinetics of one FMP bacterium, Lactococcus lactis CNCM I-1631, were dependent on the structure of the resident gut microbiota. Susceptibility of the resident gut microbiota to modulation by FMP intervention correlated with increased persistence of L. lactis. We also observed gut microbiome configurations that were associated with altered stability upon exposure to transient bacteria. Our study supports the concept that allochthonous bacteria have transient and subject-specific effects on the gut microbiome that can be leveraged to re-engineer the gut microbiome and improve dysbiosis-related diseases.

Chemical Kinetics for the Microbial Safety of Foods Treated with High Pressure Processing or Hurdles

The application of chemical kinetics is well known in food engineering, such as the use of Arrhenius plots and D- and z-values to characterize linear microbial inactivation kinetics by thermal processing. The emergence and growing commercialization of nonthermal processing technologies in the past decade provided impetus for the development of nonlinear models to describe nonlinear inactivation kinetics of foodborne microbes. One such model, the enhanced quasi-chemical kinetics (EQCK) model, postulates a mechanistic sequence of reaction steps and uses a chemical kinetics approach to developing a system of rate equations (ordinary differential equations) that provide the mathematical basis for describing an array of complex nonlinear dynamics exhibited by microbes in foods. Specifically, the EQCK model characterizes continuous growth–death–tailing dynamics (or subsets thereof) for pathogens such as Staphylococcus aureus, Listeria monocytogenes, or Escherichia coli in various food matrices (bread, turkey, ham, cheese) controlled by “hurdles” (water activity, pH, temperature, antimicrobials). The EQCK model is also used with high pressure processing (HPP), to characterize nonlinear inactivation kinetics for E. coli (inactivation plots show lag times), baro-resistant L. monocytogenes (inactivation plots show slight lag times and protracted tailing), and Bacillus amyloliquefaciens spores (inactivation plots show protracted tailing; HPP also induces spore activation and spore germination). We invoke further chemical kinetics principles by applying transition-state theory (TST) to the HPP inactivation of L. monocytogenes and develop novel dimensionless secondary models for temperature and pressure (TST temperature and TST pressure) to estimate kinetics parameters (activation energy E a and activation volume ∆V ‡), thereby offering new insights into the inactivation mechanisms of pathogenic organisms by HPP.

The dual oxidase gene BdDuox regulates the intestinal bacterial community homeostasis of Bactrocera dorsalis.

The guts of metazoans are in permanent contact with the microbial realm that includes beneficial symbionts, nonsymbionts, food-borne microbes and life-threatening pathogens. However, little is known concerning how host immunity affects gut bacterial community. Here, we analyze the role of a dual oxidase gene (BdDuox) in regulating the intestinal bacterial community homeostasis of the oriental fruit fly Bactrocera dorsalis. The results showed that knockdown of BdDuox led to an increased bacterial load, and to a decrease in the relative abundance of Enterobacteriaceae and Leuconostocaceae bacterial symbionts in the gut. The resulting dysbiosis, in turn, stimulates an immune response by activating BdDuox and promoting reactive oxygen species (ROS) production that regulates the composition and structure of the gut bacterial community to normal status by repressing the overgrowth of minor pathobionts. Our results suggest that BdDuox plays a pivotal role in regulating the homeostasis of the gut bacterial community in B. dorsalis.