Cereus Isolates Research Articles

Prevalence, attachment ability and strength of the biological control agent Bacillus thuringiensis on tomato.

Bacillus thuringiensis (Bt) is commonly used as a biological control agent (BCA) to control insect pests in edible plant production and can as such be introduced into the food chain of fresh produce. Using standard food diagnostics Bt will be detected and reported as presumptive B. cereus. Tomato plants are often sprayed with Bt biopesticides for insect control, thus these Bt BCAs can also reach the tomato fruits and persist until consumption. In this study, vine tomatoes from the retail in Belgium (Flanders) were investigated for the occurrence and residual numbers of presumptive B. cereus and Bt. Of 109 tomato samples, 61 (56%) were tested positive for presumptive B. cereus. Of the presumptive B. cereus isolates (n=213) recovered from these samples, 98% were identified as Bt by the production of parasporal crystals. Further quantitative real-time PCR assays on a subselection of Bt isolates (n=61) showed that 95% of Bt isolates were indistinguishable from Bt biopesticide strains that are approved to be used on crops in the EU. Furthermore, the attachment strength of tested Bt biopesticide strains showed easier wash-off properties if using the commercial Bt granule formulation than the unformulated lab-cultured Bt or B. cereus spore suspensions.

Bacillus cereus in the Artisanal Cheese Production Chain in Southwestern Mexico.

Bacillus cereus is associated with milk, dairy product, and dairy farm contamination. The aim of this study was to characterize strains of B. cereus in the small-scale artisanal cheese production chain in southwestern Mexico. 130 samples were collected. B. cereus isolation was performed on Mannitol Egg Yolk Polymyxin (MYP) agar. Genotyping, enterotoxigenic profile, and determination of genes involved in the formation of B. cereus biofilm were performed by PCR. An antimicrobial susceptibility test was made by broth microdilution assay. The phylogenetic analysis was performed by amplification and sequencing of 16s rRNA. B. cereus sensu lato was isolated and molecularly identified in 16 samples and B. cereus sensu stricto (B. cereus) was the most frequently isolated and identified species (81.25%). Of all the isolated B. cereus sensu lato strains, 93.75% presented at least one gene for some diarrheagenic toxins, 87.5% formed biofilms, and 18.75% were amylolytic. All B. cereus sensu lato strains were resistant to beta-lactams and folate inhibitors. A close phylogenetic relationship between isolates was found between the cheese isolates and the air isolates. Strains of B. cereus sensu lato were found in small-scale artisanal cheeses on a farm in southwestern Mexico.

Retrospective Screening of Anthrax-like Disease Induced by Bacillus tropicus str. JMT from Chinese Soft-Shell Turtles in Taiwan.

Bacillus cereus is ubiquitous in the environment and a well-known causative agent of foodborne disease. Surprisingly, more and more emerging strains of atypical B. cereus have been identified and related to severe disease in humans and mammals such as chimpanzees, apes, and bovine. Recently, the atypical B. cereus isolates, which mainly derive from North America and Africa, have drawn great attention due to the potential risk of zoonosis. The cluster of B. cereus carries several anthrax-like virulent genes that are implicated in lethal disease. However, in non-mammals, the distribution of atypical B. cereus is still unknown. In this study, we conducted a retrospective screening of the 32 isolates of Bacillus spp. from diseased Chinese soft-shelled turtles from 2016 to 2020. To recognize the causative agent, we used various methods, such as sequencing analysis using PCR-amplification of the 16S rRNA gene, multiplex PCR for discriminating, and colony morphology by following previous studies. Furthermore, the digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values were calculated, respectively, below the 70 and 96% cutoff to define species boundaries. According to the summarized results, the pathogen is taxonomically classified as Bacillus tropicus str. JMT (previous atypical Bacillus cereus). Subsequently, analyses such as targeting the unique genes using PCR and visual observation of the bacteria under various staining techniques were implemented in our study. Our findings show that all (32/32, 100%) isolates in this retrospective screening share similar phenotypical properties and carry the protective antigen (PA), edema factor (EF), hyaluronic acid (HA), and exopolysaccharide (Bps) genes on their plasmids. In this study, the results indicate that the geographic distribution and host range of B. tropicus were previously underestimated.

Pseudomonas aeruginosa and Bacillus cereus Isolated from Brazilian Cerrado Soil Act as Phosphate-Solubilizing Bacteria

The phosphate-solubilizing microorganism is essential for soil quality and plant development and can serve as an alternative to reduce such Brazilian needs for importing phosphate overseas. Here, we isolated and selected bacteria from Brazilian Cerrado soils capable of solubilize phosphate. We obtained 53 bacteria isolates, of which 23 could solubilize phosphate at a pH of 7.0, 17 could solubilize phosphate at a pH of 6.0, and 8 could solubilize at a pH of 5.5. Using 16S rRNA gene sequences, we identified nine bacteria species clustered in four groups: Bacillus sp., Pseudomonas sp., Priestia sp., and Klebsiella sp. Our results revealed that the UFT01 (P. aeruginosa) and UFT42 (B. cereus) isolates exhibited the best phosphate solubilization performance at all tested pH values. We further recorded higher levels of solubilization and phosphate availability six days after the soil inoculation with P. aeruginosa, and enzymatic analysis of the soil samples revealed that the P. aeruginosa-inoculated samples resulted in four-fold higher enzymatic activities when compared to non-inoculated soils. The B. cereus soil inoculation increased β-glucosidase activities and resulted in reduced the activities of arylsulfatase. Altogether, our findings demonstrated that P. aeruginosa and B. cereus isolated from Cerrado soils showed high phosphate solubilization potential.

Temporal Dynamics of Potassium Release from Waste Mica as Influenced by Potassium Mobilizing Bacteria

Potassium mobilizing bacteria (KMB) strains have been isolated from waste mica mines in the Giridih district of Jharkhand, India, using Alexandrov media. These isolates were evaluated for their potential to dissolve water soluble-K from waste mica (muscovite and biotite). Identity was confirmed based on sequencing of 16S rDNA region of those isolates showing promising water soluble-K dissolving capacity. Strains were found to be different isolates of Bacillus cereus, two unconfirmed Bacillus species (strain- 6SB1 and GG6), and one each of B. velezensis and Paraburkholderia kururiensis. Finally, the four most efficient KMB were selected based on their K-mobilizing capability. The K5B (B. cereus) isolate showed the highest K-solubilising capacity in both muscovite and biotite enriched medium. Soil incubation study was conducted using soils of Giridih (Alfisol) with three gradient concentrations of both waste mica tailings and K-solubilising capacity of four KMB isolates (B. cereus, strain- K5B, K6, K15; and Bacillus sp. GG6- K12) were measured at 4, 7, 14 and 21 days intervals. The K release dynamics in incubated soils indicated that potassium was released from both types of micas to significantly higher water-soluble K (WS-K) and exchangeable K (Ex-K) pools due to the inoculation of KMB isolates. Apart from potassium solubilization, B. cereus strain K5B and Bacillus sp. GG6 showed capabilities to produce indole acetic acid (IAA) and gibberellic acid (GA). These results suggested that a combination of KMB strain and powdered mica tailings could be a suitable alternative to commercial chemical fertilizers and maintain soil nutrient status for plant uptake.

Characterization of the biosurfactant production and enzymatic potential of bacteria isolated from an oil-contaminated saline soil.

Biosurfactants are amphiphilic compounds with extensive applications in oily contaminated environments to remove hydrocarbons. Moreover, enzymes such as laccase and manganese peroxidase are responsible for the oxidation of a variety of phenolic compounds and aromatic amines. Therefore, in the present study, bacteria with the potential to produce biosurfactants and enzymes (namely, laccase, manganese peroxidase, and endoglucanase carboxymethyl cellulose (CMCase)) were isolated from petroleum oil-contaminated soil. From 15 isolated bacteria, three isolates were selected as the best producers of biosurfactants according to the related tests, such as tests for surface tension reduction. These three bacteria indicated tolerance to a salinity test and were classified as resistant and very resistant. The isolates 3, 12, 13, and 14 showed positive results for the degradation of guaiacol, phenol red, and carboxymethylcellulose, as well as the decoloration of methylene blue by the creation of a clear halo around the bacterial colony. Upon the quantitation of the laccase and manganese peroxidase activities, 22.58U/L and 21.81U/L, respectively, were measured by isolate 13. Furthermore, CMCase activity was recorded with 0.057436U/ml belonging to isolate 14. Bacterial strains with appreciable laccase, peroxidase, CMCase activity, and biosurfactant production potentials were identified through 16S rDNA sequence analysis as Bacillus sp. (isolate 3), Bacillus toyonensis (isolate 12), Bacillus cereus (isolate 13), and Bacillus tropicus (isolate 14), and their nucleotide sequences were deposited in the GenBank. The potentials for the industrial applicability of the biosurfactants and enzymes abound, and production needs to be optimized by the selected bacterial strains.

Occurrence and characterization of toxigenic Bacillus cereus in dairy products with an inactivation trial using D-Tryptophan and ascorbic acid in the rice pudding

Bacillus cereus is one of the foodborne pathogens that is incriminated in several outbreaks worldwide. The objectives of the current study were first to determine the prevalence of B. cereus-contaminated milk and dairy products retailed in Egypt. Secondly, the antimicrobial resistance profiling and virulence-associated genes of the recovered B. cereus isolates were assessed. Finally, natural and eco-friendly natural additives such as d-tryptophan and l-ascorbic acid were used for controlling the viability of Bacillus cereus spores. A total of 200 samples including market raw milk, Ultra-Heat Treated (UHT) milk, Kariesh cheese, soft white cheese (Damietta), and rice pudding, 50 of each were examined. The results of our study indicated that 31% of the examined dairy samples were contaminated with B. cereus. Surprisingly, 90% of the isolates showed multidrug-resistance against ampicillin, amoxicillin, oxacillin, and streptomycin. The molecular characterization revealed that 15 isolates harbored both hemolytic and non-hemolytic enterotoxin genes. Co-treatment of B. cereus spores-contaminated rice pudding with d-tryptophan at a concentration of 40 mM and l-ascorbic acid at a concentration of 3% revealed a significant reduction (P < 0.05) in the spore growth. Therefore, d-tryptophan and l-ascorbic acid are considered promising eco-friendly food preservatives with anti-B. cereus effects in the dairy industry.

Characterization of multidrug-resistant potential pathogens isolated from milk and some dairy products in Egypt.

This study aimed to explore the incidence and antimicrobial resistance (AMR) of Escherichia coli, Staphylococcus aureus, and Bacillus cereus in raw milk and some Egyptian dairy products, namely Kariesh cheese and rice with milk. 112 samples (70 raw milk, 30 Kariesh cheese, and 12 rice with milk) were randomly collected from different districts in Cairo and Giza, Egypt. The samples were examined for E. coli, S. aureus, and B. cereus presence. The susceptibility of the obtained isolates was tested against 11 antimicrobials using the disk diffusion method, and further, the presence of AMR genes was examined. The incidences of E. coli, S. aureus, and B. cereus were 69.64%, 12.5%, and 16.7% in the examined samples, respectively. The antibiogram indicated that E. coli isolates (n = 60) were resistant to gentamycin (73.33%), ampicillin (AM, 53.3%), and cefotaxime (CTX, 16.66%). Multidrug-resistant (MDR) E. coli strains (n = 5) were tested for β-lactams resistance genes. blaTEM was detected in all isolates, and two of them additionally carried blaCTX-M. Staphylococcus aureus isolates (n = 10) were resistant to AM (100%), followed by tetracycline (TE), CTX, and gentamycin (60% each). All MDR S. aureus strains (n = 4) carried blaZ and tetK, and three of them additionally carried aac(6')-aph (2''). Bacillus cereus isolates (n = 30) showed resistance to AM (100%), amoxicillin (20%), and TE (6.66%). bla and tetA genes were detected in all MDR B. cereus isolates (n = 6). Our findings denote the high incidence of potential health hazards in raw milk and some of its products and the existence of AMR bacteria, including MDR strains, which can cause human illnesses that are difficult to treat.

A study on toxin genes and cytotoxicity levels of Bacillus cereus in various ready-to-eat foods and pastry products in Turkey

Bacillus cereus is a spore-forming and toxin-producing gram-positive bacteria widely isolated from soils, meat, milk, and vegetables. It is recognized as one of the pathogenic bacteria that can lead to food poisoning and food spoilage in food service systems due to its ease of contamination of foods and lack of guarantee of elimination by pasteurization and sanitation practices. B. cereus causes two types of diseases mainly characterized by diarrhea and vomiting type syndrome with the toxins it produces. Toxins produced by B. cereus are mainly heat-stable emetic toxin and three different heat-labile enterotoxins. Foodborne illnesses of the diarrheal type are caused by the single protein toxin; cytotoxin K (CytK), and both tripartite toxins; hemolysin BL (Hbl), and the non-hemolytic enterotoxin (Nhe), whereas the emetic type, is caused by an emetic toxin cereulide. In this study, 225 ready-to-eat foods and pastry products were analyzed for B. cereus, its toxin profiles, and cytotoxicity effects. Multiplex PCR is used to identify the presence of the Hbl, CytK, and emetic toxin encoding genes. Component-specific antibody-based ELISA tests were utilized to determine the Hbl-L2 and NheB components. Cytotoxic activity of the B. cereus isolates on Vero cells was also identified. In total, B. cereus was detected in 37 out of 225 (16.4%) food samples. From the positive 37 B. cereus isolates, the ces gene was not identified, whereas 91.9% (34) Nhe, 56.8% (21) Hbl, and 8.1% (3) CytK encoding genes revealed positive results on PCR analysis. PCR results were also compatible with ELISA and Cytotoxicity tests. In a nutshell, 16.4% prevalence of B. cereus in foods is insufficient, and the presence or absence of toxin genes may not yield reliable results. It is critical to detect pathogenic B. cereus toxin gene profiles as well as toxin production ability at the same time. This study presents for the first time, data from a cell culture cytotoxicity test using specific monoclonal antibody-based sandwich ELISA and multiplex PCR for ready-to-eat foods and pastry products in Turkey

Bacillus cereus in Ready-to-Eat Foods Available in Kathmandu, Nepal

Objectives: The aim of this study was to assess the ready-to-eat food samples available in Kathmandu and detect if Bacillus cereus were present. Methods: A cross sectional study comprising of field and laboratory was conducted in Kathmandu, Nepal. A total of 240 ready-to-eat food samples were collected from February 2021 to January 2022 covering different food outlets of Kathmandu. The food samples were grouped into three main categories- rice, bakery, and dairy. The homogenate mixture of sample was prepared. The samples were processed following the standard microbiological procedures and Bacillus cereus was identified by different biochemical tests. Results: Out of 240 samples analyzed, 40% samples showed the presence of Bacillus cereus which was most prevalent in bakery items followed by rice and dairy items (50%, 42.5%, and 28% respectively). One of the Bacillus cereus isolates was emetic toxin-producing type as detected from the phenotypic analysis. The contamination of Bacillus cereus ranged from 1.64 to 6.83 log cfu/g and 20.8% of the samples were potentially hazardous (&gt;5 log cfu/g). Conclusion: This study reports relatively high prevalence of Bacillus cereus in ready-to-eat food samples indicating a serious public health concern. There may be a likely connection between the standards maintained during preparation, packaging, storage, and transport; and regular monitoring of ready-to-eat food items is imperative to prevent any food poisoning incidences.

Mixed heavy metal stress induces global iron starvation response

Multiple heavy metal contamination is an increasingly common global problem. Heavy metals have the potential to disrupt microbially mediated biogeochemical cycling. However, systems-level studies on the effects of combinations of heavy metals on bacteria are lacking. For this study, we focused on the Oak Ridge Reservation (ORR; Oak Ridge, TN, USA) subsurface which is contaminated with several heavy metals and high concentrations of nitrate. Using a native Bacillus cereus isolate that represents a dominant species at this site, we assessed the combined impact of eight metal contaminants, all at site-relevant concentrations, on cell processes through an integrated multi-omics approach that included discovery proteomics, targeted metabolomics, and targeted gene-expression profiling. The combination of eight metals impacted cell physiology in a manner that could not have been predicted from summing phenotypic responses to the individual metals. Exposure to the metal mixture elicited a global iron starvation response not observed during individual metal exposures. This disruption of iron homeostasis resulted in decreased activity of the iron-cofactor-containing nitrate and nitrite reductases, both of which are important in biological nitrate removal at the site. We propose that the combinatorial effects of simultaneous exposure to multiple heavy metals is an underappreciated yet significant form of cell stress in the environment with the potential to disrupt global nutrient cycles and to impede bioremediation efforts at mixed waste sites. Our work underscores the need to shift from single- to multi-metal studies for assessing and predicting the impacts of complex contaminants on microbial systems.

Conjugation across Bacillus cereus and kin: A review.

Horizontal gene transfer (HGT) is a major driving force in shaping bacterial communities. Key elements responsible for HGT are conjugation-like events and transmissible plasmids. Conjugative plasmids can promote their own transfer as well as that of co-resident plasmids. Bacillus cereus and relatives harbor a plethora of plasmids, including conjugative plasmids, which are at the heart of the group species differentiation and specification. Since the first report of a conjugation-like event between strains of B. cereus sensu lato (s.l.) 40 years ago, many have studied the potential of plasmid transfer across the group, especially for plasmids encoding major toxins. Over the years, more than 20 plasmids from B. cereus isolates have been reported as conjugative. However, with the increasing number of genomic data available, in silico analyses indicate that more plasmids from B. cereus s.l. genomes present self-transfer potential. B. cereus s.l. bacteria occupy diverse environmental niches, which were mimicked in laboratory conditions to study conjugation-related mechanisms. Laboratory mating conditions remain nonetheless simplistic compared to the complex interactions occurring in natural environments. Given the health, economic and ecological importance of strains of B. cereus s.l., it is of prime importance to consider the impact of conjugation within this bacterial group.

Enterotoxin genes, biofilm formation, and antimicrobial and disinfectant resistance of Bacillus cereus isolates from primary producing stages

In this study, we analyzed enterotoxin genes, biofilm formation, and resistance to sixteen antimicrobials and chlorine dioxide (ClO 2 ) in Bacillus cereus group isolates ( n = 76) from samples (leaves, seeds, water and nutrients, and soil) from microgreen primary producing farms. Most isolates possessed at least one enterotoxin gene, as well as resistance to β-lactam antimicrobials, and more than half of the isolates showed moderate to strong biofilm-forming ability. Several B. cereus isolates with strong biofilm-forming ability survived ClO 2 treatment, thereby preventing their decontamination in samples from microgreen producing farms. When the B. cereus group isolates were treated with ClO 2 for 5 min, antimicrobial resistance to rifampin and gentamicin increased. These results provide a useful insight into the development of risk management technologies to ensure the food safety of fresh produce, including microgreens, with a particular focus on the primary production stages. • Bacillus cereus group isolates from microgreen primary producing farms were studied. • Most of the isolates possessed at least one enterotoxin gene. • None of the isolates were susceptible to β-lactams and fluoroquinolones. • Some B. cereus showed strong biofilm-forming ability and resistance to ClO 2 . • Resistance to several antimicrobials was increased after exposure to ClO 2 .

Short Communication: Enterotoxin Genes and Antibiotic Susceptibility of Bacillus cereus Isolated from Garlic Chives and Agricultural Environment.

This study aims to investigate the enterotoxin profiles and antibiotic susceptibility of Bacillus cereus isolated from garlic chives and environmental samples. A total of 103 B. cereus isolates were used to identify enterotoxin genes, including hblA, hblC, hblD, nheA, nheB, and nheC. The hemolysin BL enterotoxin complex (hblACD) was detected in 38 isolates (36.9%), and the non-hemolytic enterotoxin complex (nheABC) was detected in 8 (7.8%) isolates. Forty-five isolates (43.7%) had hblACD and nheABC genes. B. cereus was resistant to β-lactam antibiotics and susceptible to non-β-lactam antibiotics. However, some B. cereus strains showed intermediate resistance to β-lactam and non-β-lactam antibiotics. B. cereus isolated from garlic chives showed intermediate resistance to cefotaxime (7.7%), rifampin (15.4%), clindamycin (30.8%), erythromycin (7.7%), and tetracycline (7.7%). B. cereus isolates from the agricultural environment were moderately resistant to cefotaxime (18.9%), rifampin (15.6%), clindamycin (12.2%), erythromycin (4.4%), and tetracycline (5.6%). Moreover, B. cereus isolates from garlic chives and cultivation environments could change their antibiotic resistance profile from susceptible to intermediate-resistant to rifampin, clindamycin, erythromycin, and tetracycline and exhibit multidrug resistance. These results indicate that continuous monitoring of B. cereus contamination in the produce and agricultural environment might be needed to ensure the safety of consuming fresh vegetables.

Modelling adhesion and biofilm formation by Bacillus cereus isolated from dairy products as a function of pH, temperature and time

This study aimed to establish a mathematical model capable of predicting the adhesion and biofilm formation by Bacillus cereus isolates on stainless steel surface under different combinations of pH, temperature and time. Logistic regression models were developed to predict the probability of adhesion or biofilm formation on the surface by the pathogen. The factors temperature, pH and time influenced adhesion and biofilm formation responses, where higher temperatures (25 and 32 °C) and pH values (6.0, 7.5 and 9.0) led to more robust biofilm formation than lower temperatures (5 and 15 °C) and the lowest pH value (4.5). Isolate 3 showed greater adhesion capacity compared with the other two isolates at low temperature. The combination of pH 4.5 and temperature of 5 °C avoided bacterial adhesion and biofilm formation during the incubation period. The probabilistic models obtained were effective to describe the interface region of adhesion/non-adhesion and biofilm formation/non-biofilm formation.

Isolation, Partial Characterization and Application of Bacteriophages in Eradicating Biofilm Formation by Bacillus cereus on Stainless Steel Surfaces in Food Processing Facilities

The Bacillus cereus (B. cereus) group is a widespread foodborne pathogen with a persistent ability to form biofilm, and with inherent resistance to traditional treatment in the food industry. Bacteriophages are a promising biocontrol agent that could be applied to prevent or eliminate biofilms formation. We have described, in this study, the isolation from sewage samples and preliminary characterization of bacteriophages that are active against the B. cereus group. The effectiveness of phage treatment for reducing B. cereus attachment and biofilms on stainless steel surfaces has been also assessed using three incubation periods at different titrations of each phage. Out of 62 phages isolated, seven showed broad-spectrum lytic action against 174 B. cereus isolates. All selected phages appeared to be of the Siphoviridae family. SDS-PAGE proved that two phages have a similar profile, while the remainder are distinct. All isolated phages have the same restriction pattern, with an estimated genome size of around 37 kb. The isolated bacteriophages have been shown to be effective in preventing biofilm formation. Reductions of up to 1.5 log10 UFC/cm2 have been achieved, compared to the untreated biofilms. Curative treatment reduced the bacterial density by 0.5 log10 UFC/cm2. These results support the prospect of using these phages as a potential alternative strategy for controlling biofilms in food systems.

FTIR (Fourier Transform Infrared) Spectroscopy Method for Bacillus cereus Characterization

One of the potentials of Bacillus cereus bacteria is as an inducer of systemic resistance in plants against plant diseases. FTIR spectroscopy is a traditional method extensively utilized in the pharmaceutical industry, since it is fast, non-destructive, and requires minimal sample preparation. In this study, the indicators that were effectively discovered were the functional groups that compose carbohydrates and lipids. The absorption region to be analyzed for the functional groups that compose carbohydrates is in the wavenumber region of 1200-800 cm-1, whereas the functional groups that compose up lipids are in the wavenumber range of 3020-2800 cm-1 and 1800-800 cm-1. The signal produced on the spectral signature of B. cereus isolates revealing the functional groups that compose carbohydrates is at the absorption values of 1185, 1132, 1122, 1098, 1078, 1056, 1010, and 973 cm-1. This is analogous to the notion that the cell wall of B. cereus is composed of peptidoglycan which contains carbohydrates. While the absorption values that indicate the functional groups that make up lipids are 2969, 2955, 2925, 2870, 2846, 1759, 1733, 1471, 1455, 1234, 895 cm-1, which according to the literature suggests that the body structure of B. cereus contains 2-3% of the dry weight of bacterial cells and consists of neutral lipids and phospholipids.

FTIR (Fourier Transform Infrared) Spectroscopy Method for Bacillus cereus Characterization

One of the potentials of Bacillus cereus bacteria is as an inducer of systemic resistance in plants against plant diseases. FTIR spectroscopy is a traditional method extensively utilized in the pharmaceutical industry, since it is fast, non-destructive, and requires minimal sample preparation. In this study, the indicators that were effectively discovered were the functional groups that compose carbohydrates and lipids. The absorption region to be analyzed for the functional groups that compose carbohydrates is in the wavenumber region of 1200-800 cm-1, whereas the functional groups that compose up lipids are in the wavenumber range of 3020-2800 cm-1 and 1800-800 cm-1. The signal produced on the spectral signature of B. cereus isolates revealing the functional groups that compose carbohydrates is at the absorption values of 1185, 1132, 1122, 1098, 1078, 1056, 1010, and 973 cm-1. This is analogous to the notion that the cell wall of B. cereus is composed of peptidoglycan which contains carbohydrates. While the absorption values that indicate the functional groups that make up lipids are 2969, 2955, 2925, 2870, 2846, 1759, 1733, 1471, 1455, 1234, 895 cm-1, which according to the literature suggests that the body structure of B. cereus contains 2-3% of the dry weight of bacterial cells and consists of neutral lipids and phospholipids.

Occurrence of selected bacterial pathogens in insect-based food products and in-depth characterisation of detected Bacillus cereus group isolates

Insects are increasingly used as alternative protein sources and ingredients of foodstuffs produced in industrial scale. Previous studies on the microbial status of insect-based foods revealed that classical foodborne pathogens such as Salmonella spp., Campylobacter spp., Listeria monocytogenes or pathogenic Escherichia coli are rarely detected, whereas particularly spore-forming bacteria with pathogenic potential such as species of the Bacillus cereus group or Clostridium species may pose a food safety risk. However, detailed descriptions of the encountered pathogenic bacteria in insect foods are scarce.We investigated a variety of 73 food products with insect or other arthropod ingredients on the occurrence of potential bacterial pathogens. These included B. cereus (sensu lato (s.l.)), Clostridium perfringens and Clostridioides difficile as representatives of spore-formers and Salmonella spp. and Shiga toxin producing and enteropathogenic E. coli (STEC/EPEC) as representatives of non-spore-forming Enterobacteriaceae.Most of the investigated food products complied with food safety standards regarding the presence of pathogens considered. However, one cricket product contained two Salmonella enterica subspecies enterica serovars (S. Wandsworth and S. Stanley). B. cereus (s.l.) was found in 42 samples (58 %), of which six contained B. cereus (s.l.) at levels higher than 103 cfu/g. The highest B. cereus (s.l.) counts of 3.8 × 105 cfu/g were found in a product with boiled and dried scorpions. Clostridium perfringens was detected in twelve samples (16 %), whereas Clostridioides difficile and STEC/EPEC were not detected in any of the samples.Remarkably, five samples contained the B. cereus (s.l.) species B. cytotoxicus. Moreover, strikingly high numbers of B. cereus (s.l.) isolates carried the capsule syntheses genes capBCADE, which were presumably located on the B. cereus pBFI_2 plasmid. Whole genome sequencing-based phylogenetic analysis suggested a high relatedness for only very few of the B. cytotoxicus and cap-positive isolates, respectively.

Maize growth response to different Bacillus strains isolated from a salt-marshland area under salinity stress

Maize (Zea mays) growth performance has been hindered due to the high soil salinity. Salinity is one of the most severe abiotic stresses that has led to growth imbalance and profitability of harvests in arid and semi-arid regions. Plants have taken advantage of salt-tolerant bacteria as plant growth-promoters to enhance growth and reduce the adverse effects of salinity through the regulation of some biochemical, physiological, and molecular features. Preferences for non-chemical, eco-friendly, and economical approaches have caused the inquiry of the Bacillus genus as a joint group of plant growth-promoting rhizobacteria known to alleviate salt-stress impacts. In the present study, halotolerant Bacillus strains were isolated from salt-marshland soil and characterized for their physiological, molecular, and biochemical properties. Twenty-four bacterial isolates collected from high saline fields of salt marshland were analyzed by MALDI-TOF MS proteome analysis, which confirmed the taxonomic affiliation with Bacillus cereus, Bacillus subtilis, Bacillus atrophaeus, and Bacillus thorngiensis. Applying the isolates on maize plants as bio-inoculant bacteria obviously increased the growth parameters (P < 0.01). Pot experiments showed that isolates 74 and 90 were the most prominent strains to minimize the harmful effects of salinity. Its effects are heightening the potassium/sodium ratio and K-Na selectivity in shoots and roots measured by flame atomic absorption photometry (AAS). Accordingly, Bacillus cereus isolate 74 showed a maximum increase in dry weights of the shoot (133.89%), root (237.08%), length of the shoot (125%), and root (119.44%) compared to the control condition. Our findings suggest that bacteria isolated from marshland may be an economical and simple means to increase plant growth and resistance to high salinity soil conditions.