Cereus Isolates Research Articles

First insights into the prevalence, genetic characteristics, and pathogenicity of Bacillus cereus from generations worldwide.

Bacillus cereus, a global threat, is one of the major causes of toxin-induced foodborne diseases. However, a comprehensive assessment of the prevalence and characteristics of B. cereus worldwide is still lacking. Here, we applied whole-genome sequence analysis to 191 B. cereus collected in Africa, America, Asia, Europe, and Oceania from the 1900s to 2022, finding that CC142 dominated the global B. cereus clonal complex. The results provided direct evidence that B. cereus could spread through the food chain and intercontinentally. B. cereus from different generations worldwide showed coherence in the antibiotic-resistant gene and virulence and biofilm gene profiles, although with high genomic heterogeneity. The BCI-BCII-vanZF-fosB profiles and virulence and biofilm genes were detected at high rates, and we emphasized that B. cereus would pose a serious challenge to global public health and clinical treatment.IMPORTANCEThis study first emphasized the prevalence, genetic characteristics, and pathogenicity of Bacillus cereus worldwide from the 1900s to 2022 using whole-genome sequence analysis. The CC142 dominated the global Bacillus cereus clonal complex. Moreover, we revealed a close evolutionary relationship between the isolates from different sources. B. cereus isolates from different generations worldwide showed coherence in potential pathogenicity, although with high genomic heterogeneity. The BCI-BCII-vanZF-fosB profiles and virulence and biofilm genes were detected at high rates, and we emphasized that B. cereus would pose a serious challenge to global public health and clinical treatment.

The Effect of Aqueous and Alcoholic Extracts of Punica granatum L. Pericarp on Hemolysin Production of several Bacterial species

Four local hemolysin producer bacterial isolates were selected, tow of them gram negative bacteria (Escherichia coli ,Pseudomonas aeruginosa ) and the other two were gram positive bacteria (Staphylococcus aureus , Bacillus cereus ). Minimum inhibitory concentration of the aqueous and alcoholic extracts of Punica granatum L. pericarp were determined towards the four bacterial isolates ,results obtaind showed that MICs of the aqueous extract were 200 mg/ml for E .coli and P. aeruginosa isolates while were 5 mg/ml and 2 mg/ml for B. cereus, S. aureus , respectively The MICs for the ethanolic extract were 50 mg/ml , 20 mg/ml ,1 mg/ml ,0.5 mg/ml for E. coli ,P. aeruginosa ,B. cereus ,S. aureus , respectively. The effect of Sub-MICs of the aqueous and alcoholic extracts on hemolysin production was investigated , both extracts had a suppressing effect on hemolysin production by E. coli ,P. aeruginosa ,while both extract had an inhibitory effect on hemolysin production by S. aureus and B . cereus isolates

Potential risk of biofilm-forming Bacillus cereus group in fresh-cut lettuce production chain

Bacillus cereus and Bacillus thuringiensis, which belong to the B. cereus group, are widely distributed in nature and can cause food poisoning symptoms. In this study, we collected 131 isolates belonging to the B. cereus group, comprising 124B. cereus and seven B. thuringiensis isolates, from fresh-cut lettuce production chain and investigated their potential risk by analyzing genotypic (enterotoxin and emetic toxin gene profiles) and phenotypic (antibiotic susceptibility, sporulation, and biofilm formation) characteristics. Enterotoxin genes were present only in B. cereus, whereas the emetic toxin gene was not detected in any of the B. cereus isolates. All isolates were susceptible to vancomycin, which is a last resort for treating B. cereus group infection symptoms, but generally resistant to β-lactam antimicrobials, and had the ability to form spores (at an average sporulation rate of 24.6 %) and biofilms at 30 °C. Isolates that formed strong biofilms at 30 °C had a superior possibility of forming a dense biofilm by proliferating at 10 °C compared to other isolates. Additionally, confocal laser scanning microscopy (CLSM) images revealed a notable presence of spores within the submerged biofilm formed at 10 °C, and the strengthened attachment of biofilm inner cells to the substrate was further revealed through biofilm structure parameters analysis. Collectively, our study revealed the prevalence and contamination levels of B. cereus and B. thuringiensis at fresh-cut lettuce production chain and investigated their genotypic and phenotypic characteristics, aiming to provide valuable insights for the development of potential risk management strategies to ensure food safety, especially along the cold chain.

Control of coptis root rot by combination of Bacillus cereus isolate Y9 and other antagonistic microorganisms

Root rot is a destructive soil-borne disease of Coptis chinensis, which depends on chemical control at present, and more attention should be paid to biocontrol of disease. In the present research, isolate Y9 isolated from healthy root samples of Coptis, was identified as Bacillus cereus. Further screening and pot experiments showed that B. cereus isolate Y9 inhibited the growth of the main causal agents of coptis root rot disease (Fusarium solani and F. avenaceum) and seven other phytopathogenic fungi. The application of B. cereus isolate Y9 and compatible Trichoderma harzianum, T. atroviride and B. amyloliquefaciens, singly and in combination were found to be effective against Fusarium root rot in vitro and in field experiments. In field experiments, combinations of T. harzianum + B. amyloliquefaciens + Y9 (HYJ, in ratio of 1:1:1) showed the highest control efficacy of 63.85%, which was higher than the expected value (53.18%), indicating synergistic effect on the control of coptis root rot. Therefore, B. cereus isolate Y9 may be a potential biological control agent, and combined use with T. harzianum and B. amyloquefaciens offered even greater potential. The long-term effects of isolate B. cereus Y9 and its combinations on C. chinensis should be assessed in different locations and seasons in the future.

Alkaline-Tolerant Bacillus cereus 12GS: A Promising Polyhydroxybutyrate (PHB) Producer Isolated from the North of Mexico.

Environmental pollution caused by petroleum-derived plastics continues to increase annually. Consequently, current research is interested in the search for eco-friendly bacterial polymers. The importance of Bacillus bacteria as producers of polyhydroxyalkanoates (PHAs) has been recognized because of their physiological and genetic qualities. In this study, twenty strains of Bacillus genus PHA producers were isolated. Production was initially evaluated qualitatively to screen the strains, and subsequently, the strain B12 or Bacillus sp. 12GS, with the highest production, was selected through liquid fermentation. Biochemical and molecular identification revealed it as a novel isolate of Bacillus cereus. Production optimization was carried out using the Taguchi methodology, determining the optimal parameters as 30 °C, pH 8, 150 rpm, and 4% inoculum, resulting in 87% and 1.91 g/L of polyhydroxybutyrate (PHB). Kinetic studies demonstrated a higher production within 48 h. The produced biopolymer was analyzed using Fourier-transform infrared spectroscopy (FTIR), confirming the production of short-chain-length (scl) polyhydroxyalkanoate, named PHB, and differential scanning calorimetry (DSC) analysis revealed thermal properties, making it a promising material for various applications. The novel B. cereus isolate exhibited a high %PHB, emphasizing the importance of bioprospecting, study, and characterization for strains with biotechnological potential.

Bacillus cereus cereolysin O induces pyroptosis in an undecapeptide-dependent manner

Bacillus cereus is a clinically significant foodborne pathogen that causes severe gastrointestinal and non-gastrointestinal disease. Cereolysin O (CLO) is a putative virulence factor of B. cereus, and its function remains to be investigated. In this study, we examined the biological activity of CLO from a deep sea B. cereus isolate. CLO was highly toxic to mammalian cells and triggered pyroptosis through NLRP3 inflammasome-mediated caspase 1 and gasdermin D activation. CLO-induced cell death involved ROS accumulation and K+ efflux, and was blocked by serum lipids. CLO bound specifically to cholesterol, and this binding was essential to CLO cytotoxicity. The structural integrity of the three tryptophan residues in the C-terminal undecapeptide was vital for CLO to interact with membrane lipids and cause membrane perforation. Taken together, these results provided new insights into the molecular mechanism of B. cereus CLO-mediated cytotoxicity.

Occurrence and risk‐related features of Bacillus cereus in fluid milk

This work assessed the prevalence and risk‐related phenotypes of Bacillus cereus in milk products. Bacillus was the most dominant genus of 113 collected strains from 41 milk samples, and B. cereus (19.27%) was the most abundant species showing a high genetic diversity with seven random amplified polymorphic DNA patterns. Most B. cereus isolates were strong biofilm formers with good motility, extracellular polymeric substance‐producing ability, high proteolytic and lipolytic activities. Antibiotic resistance analysis suggested the majority B. cereus strains were resistant to oxacillin (90.48%), tetracycline (95.24%), and penicillin G sodium (47.62%). Results revealed the genotypic diversity of B. cereus, and their potential risk in dairy industry.

Apple cider vinegar exhibits promising antibiofilm activity against multidrug-resistant Bacillus cereus isolated from meat and their products.

Bacillus cereus (B. cereus) biofilm is grown not only on medical devices but also on different substrata and is considered a potential hazard in the food industry. Quorum sensing plays a serious role in the synthesis of biofilm with its surrounding extracellular matrix enabling irreversible connection of the bacteria. The goal of the current investigation was to ascertain the prevalence, patterns of antimicrobial resistance, and capacity for B. cereus biofilm formation in meat and meat products in Egypt. In all, 150 meat and meat product samples were used in this study. For additional bacteriological analysis, the samples were moved to the Bacteriology Laboratory. Thereafter, the antimicrobial, antiquorum sensing, and antibiofilm potential of apple cider vinegar (ACV) on B. cereus were evaluated. Out of 150 samples, 34 (22.67%) tested positive for B. cereus. According to tests for antimicrobial susceptibility, every B. cereus isolates tested positive for colistin and ampicillin but negative for ciprofloxacin and imipenem. The ability to form biofilms was present in all 12 multidrug-resistant B. cereus isolates (n = 12); of these, 6 (50%), 3 (25%), and 3 (25%) isolates were weak, moderate, and strong biofilm producers, respectively. It is noteworthy that the ACV demonstrated significant inhibitory effects on B. cereus isolates, with minimum inhibitory concentrations varying between 2 and 8 μg/ml. Furthermore, after exposing biofilm-producing B. cereus isolates to the minimum biofilm inhibitory concentrations 50 of 4 μg/ml, it demonstrated good antibiofilm activity (>50% reduction of biofilm formation). Strong biofilm producers had down-regulated biofilm genes (tasA and sipW) and their regulator (plcR) compared to the control group, according to reverse transcriptase quantitative polymerase chain reaction analysis. Our study is the first report, that spotlights the ACV activity against B. cereus biofilm and its consequence as a strong antibacterial and antibiofilm agent in the food industry and human health risk.

The Effect of Bacillus Cereus on the Ion Homeostasis, Growth Parameters, and the Expression of Some Genes of Artemisinin Biosynthesis Pathway in Artemisia Absinthium Under Salinity Stress.

Soil salinity is a major problem in the world that affects the growth and yield of plants. Application of new and up-to-date techniques can help plants in dealing with salinity stress. One of the approaches for reducing environmental stress is the use of rhizosphere bacteria. The aim of present study was to investigate the effect of the inoculation of Bacillus cereus on physiological and biochemical indicators and the expression of some key genes involved in the Artemisinin biosynthesis pathway in Artemisia absinthium under salinity stress. The study was conducted using three different salinity levels (0, 75, 150 mM/NaCl) and two different bacterial treatments (i. e, without bacterial inoculation and co-inoculation with B. cereus isolates). The data from the experiments were analyzed using factorial analysis, and the resulting interaction effects were subsequently examined and discussed. The results showed that with increasing salinity, root and stem length, root and stem weight, root and stem dry weight, and potassium content were decreased, although the content of sodium was increased. Rhizosphere bacteria increased the contents of Artemisinin, potassium, calcium, magnesium, and iron and the expression of Amorpha-4,11-diene synthase and Cytochrome P450 monooxygenase1 genes as well as the growth indicators; although decreased the sodium content. The highest ADS expression was related to co-inoculation with B. cereus isolates E and B in 150 mM salinity. The highest CYP71AV1 expression was related to co-inoculation with B. cereus isolates E and B in 150 mM salinity. These findings showed that the increase in growth indices under salinity stress was probably due to the improvement of nutrient absorption conditions as a result of ion homeostasis, sodium ion reduction and Artemisinin production conditions by rhizosphere B. cereus isolates E and B.

Characterization of Bacillus cereus isolated from contaminated foods with sequencing of virulence genes in Egypt.

The current study describes the presence of Bacillus cereus (B. cereus) in contaminated foods of animal source and ready for human consumption with highlighting on their virulence contributing factors by detection of its virulence genes in addition to identification of their sequencing. Three hundred sixty food samples categorized as (228) meat products and (132) milk products were examined for B. cereus isolation and all of these isolates were confirmed by biochemical tests. Eighteen strains obtained from different food samples were examined for the attendance of a number of virulence genes (nheA, cytK, entFM, bceT and hblC genes) using uniplex PCR method. Furthermore, the B. cereus strains were valued for the sequencing of described genes. Generally 24.44% (88/360) food samples classified as 11.11% (40/360) meat products and 13.33% (48/360) milk products carried B. cereus according to cultural and biochemical properties, with geometric mean (1.5×107±0.15 CFU/g or mL) . The highest counts (above 105 CFU/g or mL) were originated from milk products (with geometric mean 2.2×107±0.22 CFU/g or mL) more than meat products (with geometric mean 1×107±0.19 CFU/g or mL). The results revealed that all of our isolates had one or more virulence (enterotoxin) genes. In our research, the most predominant genes were nheA (100%), followed by cytK (61.11%), entFM (33.33%), bceT (11.11%) then hblC (5.56%). Molecular method detected that overall, 5 strains (27.78%) harbored only 1 gene (nheA), 7 strains (38.88%) harbored 2 genes which classified as 5 strains (27.78%) (nheA and cytK), 2 strains (11.11%) have (nheA and entFM). Moreover, 5 strains (27.78%) have 3 genes classified as 3 strains (16.67%) harbored (nheA, cytK and entFM), 1 strain (5.56%) had (nheA, cytK and hblC), and 1 strain (5.56%) had (nheA, cytK and bceT). Only 1 strain (5.56%) carried 4 tested virulence genes (nheA, cytK, entFM and bceT) genes. The most prevalent gene in meat and dairy foods was nheA (100%). The nucleotide sequences of (bceT, cytK, entFM, hblC and nheA genes) of B. cereus strains were deposited in GenBank under accession no. (MW911824, MW911825, MW911826, MW911827 and MW911828), respectively. Our study was established to indicate the presence of virulent B. cereus in meat and milk products ready for human consumption as a result of deficient hygienic actions. So, a plain for good hygienic measures should be modified to avoid causing serious health problems to human due to ingestion of such products.

Molecular Characterization and Genetic diversity of Bacillus cereus isolated from karish cheese at Governorate of El-Menoufia

Food safety is an emerging global issue that impacts world trade and human health. Bacillus cereus is among the most significant global foods borne pathogens. 50 total random samples of karish cheese were obtained from a variety of food markets in Governorate of El-Menoufia. They were investigated bacteriologically in order to isolate, B. cereus species. According to the bacteriological analysis, 70% of the tested samples of karish cheese contained B. cereus species. The B. cereus isolates were resistance to Amoxicillin, Penicillin, and Amoxicillin Clavulanic acid. Contrarily, they were susceptible to Ciprofloxacin, Gentamicin, Chloramphenicol, Tetracycline and Trimethoprim Sulfamethoxazole.

Inhibitory effect of some probiotic strains and essential oils on the growth of some foodborne pathogens.

Bacillus cereus and Yersinia enterocolitica are implicated in foodborne diseases that have major effects on human health; therefore, it is considered universal public health disorders. Essential oils and essential oils nano emulsions have a sufficient antibacterial performance against a variety of bacteria, especially multi-drug resistant bacteria. Probiotics showed several health benefits via moderating the GIT microbiota and their metabolites. The study was designed to evaluate the biocontrol ability of cinnamon essential oil (CEO) nano emulsion and probiotics as natural antibacterial additives and reveal their bactericidal mechanism. 250 random samples (50 raw milk, 50 rice pudding, 50 kariesh cheese, 50 yogurt, and 50 ice cream) were purchased separately from different areas in Mansoura city, Egypt, and exposed to bacteriological analysis. Bacillus cereus was found with the highest mean value of 66 × 107 ± 1.3 × 108 CFU/g in raw milk and the lowest mean value of 28 × 107 ± 2.6 × 107 CFU/g in kariesh cheese while Y. enterocolitica was found in 64% of the total inspected samples with the highest incidence (84%) in yogurt. The toxinogenic potential of the tested pathogens has been evaluated by multiplex PCR pointing nhe A and ces genes for B. cereus isolates while targeting in Y. enterocolitica 16s rRNA, and YST gene. Different concentrations (0.17%, 0.25%, 0.5%, 0.8%, 1%, 1.5%, and 2%) of cinnamon oil nano emulsion were employed in this study. CEO nano emulsion had the highest reduction rate at a concentration of 1.5% in the case of B. cereus and 2% in the case of Y. enterocolitica. Among different types of probiotics, the best one which showed inhibitory potential against B. cereus and Y. enterocolitica was L. plantarum. Lactobacillus plantarum and CEO nano emulsion at a concentration of 2% have the highest reduction rate against Y. enterocolitica, while L. plantarum and CEO nano emulsion at a concentration of 1.5% has the best antibacterial effect against B. cereus. In conclusion, more attention is required for both safety and quality in dairy products through the application of natural additives such as essential oils and probiotics.

Potential of Compost Enriched with Bacillus velezensis B-27 and Bacillus cereus RC76 for the Management of Twisted Disease on Shallots

Shallot (Allium cepa var. aggregatum.) is a horticultural plant that is widely consumed in the world. However, the productivity of shallots in Indonesia is still relatively low, if compared to the actual optimum production potential of shallot. Shallot cultivation in Indonesia often experiences many problems. One of the problems is twisted diseases caused by Fusarium sp. This research aimed to study the effect of the application of organic material enriched with Bacillus in suppressing the development of twisted disease of shallot. This study was arranged in Randomized Complete Block Design (RCBD) with 5 treatments namely (A) compost + Bacillus velezensis isolate B-27, (B) compost + Bacillus cereus isolate RC76, (C) B. velezensis isolate B-27+B. cereus isolate RC76+compost, (D) compost + Trichoderma asperellum and (E) control (compost 1 ton/ha) with 5 replications on glasshouse treatment and 3 replications on field treatment. The results showed that the combination of B. velezensis in compost effectively reduced the incidence of twisted disease, the number of Fusarium spp. colonies, and the number of infected bulbs by Fusarium sp. Besides, the combination of compost with microbial agents showed better results than compost single treatment.

Влияние солей железа на ростовые характеристики и антагонистическую активность почвенных изолятов Bacillus cereus

The research is devoted to study of the effect of iron salts on the growth characteristics and antagonistic activity against Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium bacteria Bacillus cereus. 9 strains of B. cereus bacteria, previously isolated from soils, were used as objects of research, which showed different resistance to solutions of iron salts in the concentration range from 1 M/l to 0.031 M/l. In the course of the work, the following methods were used: serial breeding, seeding and cultivation of bacteria on nutrient media, MALDI ToF MS, agar wells and nephelometric. The maximum values of tolerance and growth were recorded in the B. cereus strain OCT2022.6, which was slightly inferior to OCT2022.2 and OCT2022.9, showing relative resistance to both nitrate and iron sulfate. The pronounced antagonistic properties of the strains were manifested against the background of pre-incubation with iron nitrate in relation to E. coli and P. aeruginosa, and in the sulfate variant, suppression was noted only for 3 strains against P. aeruginosa. Iron sulfate has a more pronounced toxic effect on the growth of the tested B. cereus isolates. The OCT2022.6 strain had the highest resistance to iron nitrate and the ability to suppress opportunistic microorganisms. Keywords: BACILLUS CEREUS, IRON, TOLERANCE, ANTAGONISTIC ACTIVITY, SUPPRESSIVENESS

Profiling toxin genes and antibiotic resistance in Bacillus cereus isolated from pre-launch spacecraft.

Characterization of the microbiomes of pre-launch spacecraft in spacecraft assembly facilities is an important step in keeping crews healthy during journeys that can last several hundred days in small artificial environments in space. Bacillus cereus, a foodborne pathogenic bacterium, has the potential to be a significant source of food contamination in such environments. This bacterium is a spore-forming bacteria that resists different antimicrobial treatments in cleanrooms where spacecraft are assembled. This study evaluated 41 B. cereus isolates from four pre-launch spacecraft in spacecraft assembly facilities for their toxin gene profile and antibiotic resistance. Four enterotoxin genes (hlbC, cytK, nheA, and entFM) and two emetic toxin genes (ces and CER) were targeted for chromosomal DNA and plasmid DNA. Results showed 31.7, 7.3, 85, and 41.5% of isolates contained hblC, cytK, nheA, and entFM, respectively, in chromosomal or plasmid DNA. Overall, 37 isolates (90.2%) showed at least one enterotoxin gene. The emetic toxin gene, ces, was detected in the plasmid DNA of three isolates (7.3%). The antibiotic resistance of isolates was evaluated by the Kirby-Bauer disk diffusion procedure. All the isolates exhibited 100% susceptibility to gentamicin, 97% were susceptible to clindamycin, and 95% to chloramphenicol, imipenem, tetracycline, and vancomycin. The overall susceptibility average is 51%. However, 98% of the isolates were resistant to β-lactam antibiotics, 97.5% were resistant to sulfamethoxazole/trimethoprim, and 80% were resistant to rifampin. This study provides important information on B. cereus isolates from spacecraft assembly facilities for use in microbial monitoring programs of spacecraft.

Risk assessment of Bacillus cereus in lettuce grown in open-field and greenhouse farming systems in China: A comparative study

Abstract Objectives Bacillus cereus isolates from vegetables can cause diarrheal syndrome food poisoning. Lettuce, the most highly consumed ready-to-eat vegetable, poses a significant risk of B. cereus exposure. Hence, B. cereus monitoring and evaluation during cultivation are essential for preventing foodborne illnesses caused by this food–pathogen combination. However, the impact of different cultivation practices on B. cereus contamination in lettuce currently remains unclear. Furthermore, a validity indicator for the experimental models cannot be effectively validated under field conditions. Materials and Methods Herein, we assessed the risk of B. cereus exposure using lettuce grown under two different cultivation farming systems in China (open-field versus greenhouse) using a quantitative microbial risk assessment model. Tukey’s mean comparison method and kernel density estimation frequency distribution statistics were used for model validation using environmental samples and lettuce. Results The mean concentration of B. cereus in open-field-grown lettuce was significantly higher than that in greenhouse-grown lettuce (P<0.05). No significant differences were observed between measured, formula-calculated, and risk assessment values in environmental samples or lettuce (P>0.05), verifying the accuracy of the risk model. Conclusion Soil solarization, complete manure treatment, usage of mulch films, and irrigation water quality should be considered in agricultural practices to control B. cereus concentrations in lettuce. Overall, we found that B. cereus was more abundant in open-field-grown lettuce, and we provide a risk evaluation framework that can guide farmers and policy-makers to control B. cereus contamination in farm-to-fork lettuce chains in China.

Prevalence, Toxin Genes, and Antibiotic Resistance Profiles of Bacillus cereus Isolates from Spices in Antalya and Isparta Provinces in Türkiye.

Bacillus cereus is a pathogenic bacterium commonly found in nature and can produce toxins that cause food poisoning. This study aimed to detect the prevalence of B. cereus group bacteria in 50 unpackaged and 20 packaged spice samples frequently used as flavoring in Turkish cuisine, as well as investigate the presence of toxin genes and antibiotic resistance in the isolates. A total of 48 B. cereus group bacteria were isolated from 27 of 70 (38.57%) spice samples. The prevalence of B. cereus group bacteria in packaged (25%, 5/20) and unpackaged (44%, 22/50) spice samples did not differ significantly (P ˃ 0.05). All B. cereus group isolates were identified as B. cereus sensu stricto (B. cereus) using molecular methods. The hemolytic activity tests revealed that the most strains (44/48, 91.67%) are β-hemolytic. The distributions of toxin genes in isolates were investigated by PCR. It was determined that all isolates were identified to have 2-8 toxin genes, except B. cereus SBC3. The three most common toxin genes were found to be nheA (47/48, 97.92%), nheB (46/48, 95.83%), and entFM (46/48, 95.83%). All B. cereus isolates were susceptible to linezolid and vancomycin, while 35.42% (17/48) showed resistance to erythromycin. Multi-drug resistance (MDR) was detected in 8.3% (4/48) of B. cereus isolates, while 33.33% of the isolates showed multiple antibiotic resistance (MAR) index values higher than 0.2. The findings indicate that B. cereus may pose a health risk in packaged and unpackaged spices if present in high quantities. Therefore, the presence of B. cereus strains in both packaged and unpackaged spices should be monitored regarding consumer health and product safety.

Identification of Antimicrobial Resistance in Faecal Microbes from Wild Dugongs (Dugong dugon)

Estuarine and coastal waters are areas of potential concern for antimicrobial resistance because of the discharge of wastewater from sewage treatment plants and the run-off from urban and agricultural lands. Herein, we evaluate the antimicrobial resistance profiles in bacteria from dugongs (Dugong dugon), mammals that inhabit and feed in shallow coastal regions and, thus, are vulnerable to encountering water and sediment contaminated by human activities. Bacterial isolates were cultured from fresh faeces of four wild dugongs, as well as from one sediment sample from a dugong foraging ground in Queensland, Australia. Ten bacterial isolates underwent phenotypic antimicrobial susceptibility testing using disc diffusion and minimum inhibitory concentration testing, and genotypic resistance and virulence gene identification through whole genome sequencing. Four Staphylococcus warneri isolates and one Bacillus cereus isolate from dugong faeces were resistant to penicillin, with two S. warneri isolates also displaying resistance to trimethoprim. Four Escherichia coli isolates were all resistant to ampicillin. Resistance genes, including fosB, BcII, dfrC, blaZ, and mdfA, were identified in the isolates cultured from dugong faeces with two virulence genes (gad and lpfA) identified in all E. coli isolates. Lysinibacillus sphaericus cultured from the marine sediment and B. cereus from dugong faeces displayed phenotypic multidrug resistance (across categories of non-extended spectrum cephalosporins, penicillins and beta-lactamase inhibitors, and clindamycin; and for L. sphaericus, phosphonic acids). These results demonstrate the role that dugongs can play as a sentinel species for antimicrobial resistance in the coastal waters across their range, which includes both disturbed urban and rural regions.

Contamination of Bacillus cereus in Foods Sold at Ramadan Bazaar in Kuching, Sarawak

Every year there are reports of food poisoning involving food sold at the Ramadan bazaar and one of the causes of food poisoning is Bacillus cereus. This study aimed to determine the contamination level of B. cereus and the antimicrobial susceptibility profile of the isolates in food sold at Ramadan bazaar in Kuching, Sarawak. A total of 155 samples from five food categories were collected from six Ramadan bazaars in three locations around Kuching. Overall, 32 (21%) food samples were found positive for B. cereus. Cooked rice showed the least satisfactory levels of B. cereus among the food categories and nasi lemak was the type of food that highly contaminated with B. cereus. Antibiotic susceptibility assessment showed that B. cereus isolates were highly resistant to ampicillin, amoxicillin/clavulanic, penicillin and cefotaxime in this study. The findings of this study showed that B. cereus has the potential to cause food poisoning to Ramadan bazaar consumers due to the high mean count in some types of food. Therefore, this study can be used as basic data for B. cereus control measures in food sold at the Ramadan bazaar.

Biocontrol of Bacillus cereus by Lactobacillus plantarum in Kareish cheese and yogurt

This study aims to biocontrol of Bacillus cereus by Lactobacillus plantarum in Kareish cheese and yogurts. The minimum inhibitory concentrations (MICs), antioxidant potentials, total flavonoids content (TFC) and total phenolic content (TPC) of L. plantarum were also estimated. Results showed that incidence of B. cereus in Kareish cheese and yogurt was 16 and 4%, respectively. Four virulence genes were investigated by PCR in B. cereus isolates (n = 10). Two toxin producing genes, cytotoxin K (cytK), and phosphatidylcholine-hydrolyzing phospholipase C (Pc-plc), were detected in all B. cereus, whereas enterotoxigenic (nhe) and hemolysin BL (hbl) genes were detected in 90 and 50%, respectively. All isolates were vulnerable to erythromycin and gentamicin (100%) with intermediate sensitivity to ciprofloxacin and complete resistance to tetracycline (100%). L. plantarum showed antibacterial power against B. cereus EMCC1006 reference strain with MIC at 3.1 mg/mL. From the different concentrations (1.5, 3.1, 6.25, 12.5, 25.0, 50.0, 100.0 mg/mL) of L. plantarum which mixed with Kareish cheese and yogurt samples, the minimum concentrations displayed the excellent sensory parameters. TPC and TFC of L. plantarum CFS were 18.5 (μg GAE/g) and 2.67 (μg QE/g), respectively. Regarding antioxidant activity, IC50 of L. plantarum was 53.84 μg/mL, while IC50 of ascorbic acid was 26.36 μg/mL. In sum, L. plantarum could be used as a promising antibacterial and antioxidant agent for biocontrol of B. cereus to ensure dairy safe without negative impact on sensorial attributes.