Presence Of Spore-forming Bacteria Research Articles

Flow of spore-forming bacteria between suppliers of dairy powders and users in some developing countries: challenges and perspectives.

Spore-forming bacteria are common contaminants of milk powder and processing lines and a major concern for the dairy industry. This dairy-associated microflora was studied extensively and well characterized in developed countries (exporters of milk powder), compared to developing countries (importers). Thereby, the quality issues affecting dairy powders and derived products are not fully controlled in developing countries. That is the case in Algeria, where recombined or reconstituted pasteurized milk is of low quality, reduced shelf-life, and the related dairies faced recurrent contaminations due to spores and biofilms. The transfer of spore-forming bacteria from exporters of dairy powders to importers in developing countries is an interesting topic, not thoroughly investigated. In addition, milk powder-based products are growing worldwide and their attributes, processes and technologies need to be better understood and controlled. This review analyzes issues affecting milk powder quality, based on few studies from developing countries in comparison with current knowledge, and emphasis on the case in Algeria. It provides information on how spore-forming bacteria and their biofilms affect the quality and shelf-life of recombined pasteurized milk produced in Algeria and compromise hygiene conditions in local dairy plants. Challenges and perspectives for better management of spore transfer from exporters of dairy powders to importers in developing countries are thereby outlined. The presence of spore-forming bacteria in milk powder is a serious safety issue.Spores are not well known, characterized and controlled in importers from developing countries.Spores cause recurrent contamination of pasteurized milk and biofilm issues in Algerian dairies.Challenges are how to reduce the flow of spores in milk powder trade.Perspectives on identification targeting predominant spores and improvement of biofilm removal.

Dynamics of Geobacillus stearothermophilus and Bacillus cereus spores inoculated in different time intervals during simulated cocoa beans fermentation

The behavior of G. stearothermophilus and B. cereus during the fermentation of cocoa beans was assessed in this study. Cocoa fermentation trials lasted seven days and were conducted inoculating a cocktail of spores of strains from each species (3 log CFU/g) daily. During the fermentation period, samples were collected for enumeration of counts of G. stearothermophilus and B. cereus indigenous fermenting microorganisms, physicochemical analysis (water activity, pH, carbohydrates, and ethanol, organic acids) and volatile compounds. The findings indicated that the counts of spores of G. stearothermophilus and B. cereus during cocoa fermentation might increase in approximately 2–3 log spores/g. Even though, the inoculation of G. stearothermophilus and B. cereus spores on cocoa beans did not affect (p > 0.05) the counts of the indigenous microorganisms responsible for cocoa fermentation, the consumption of carbohydrates, production of ethanol, organic acids and volatile compounds appeared to be affected by the presence of sporeforming bacteria. These findings indicate that a deep understanding of the role of sporeforming bacteria and their metabolome through cocoa fermentation is critical. Thus, bacterial spores contaminating cocoa beans will likely be found after the fermentation and may further represent food safety or food stability issues.

Current knowledge on the microbiota of edible insects intended for human consumption: A state-of-the-art review.

Because of their positive nutritional characteristics and low environmental impact, edible insects might be considered a 'food of the future'. However, there are safety concerns associated with the consumption of insects, such as contaminating chemical and biological agents. The possible presence of pathogenic and toxigenic microorganisms is one of the main biological hazards associated with edible insects. This review presents an overview of the microbiota of edible insects, highlighting the potential risks for human health. Detailed information on the microbiota of edible insects from literature published in 2000-2019 is presented. These data show complex ecosystems, with marked variations in microbial load and diversity, among edible insects as well as stable and species-specific microbiota for some of the most popular edible insect species, such as mealworm larvae (Tenebrio molitor) and grasshoppers (Locusta migratoria). Raw edible insects generally contain high numbers of mesophilic aerobes, bacterial endospores or spore-forming bacteria, Enterobacteriaceae, lactic acid bacteria, psychrotrophic aerobes, and fungi, and potentially harmful species (i.e. pathogenic, mycotoxigenic, and spoilage microbes) may be present. Several studies have focused on reducing the microbial contamination of edible insects by applying treatments such as starvation, rinsing, thermal treatments, chilling, drying, fermentation, and marination, both alone and, sometimes, in combination. Although these studies show that various heat treatments were the most efficient methods for reducing microbial numbers, they also highlight the need for species-specific mitigation strategies. The feasibility of using edible insects as ingredients in the food industry in the development of innovative insect-based products has been explored; although, in some cases, the presence of spore-forming bacteria and other food-borne pathogens is a concern. Recent studies have shown that a risk assessment of edible insects should also include an evaluation of the incidence of antibiotic-resistance (AR) genes and antibiotic-resistant microorganisms in the production chain. Finally, as proposed in the literature, microbial hazards should be limited through the implementation of good hygienic practices during rearing, handling, processing, and storage, as well as the implementation of an appropriate HACCP system for edible insect supply chains. Another issue frequently reported in the literature is the need for a legislative framework for edible insect production, commercialisation, and trading, as well as the need for microbiological criteria specifically tailored for edible insects. Microbiological criteria like those already been established for the food safety and hygiene (e.g. those in the European Union food law) of different food categories (e.g. ready-to-eat products) could be applied to edible insect-based products.

Bread enriched with cricket powder (Acheta domesticus): A technological, microbiological and nutritional evaluation

Abstract Recently, the high nutritional value of edible insects attracted the attention of researchers and food industry for their potential use in foods with enhanced nutritional characteristics. In this study cricket (Acheta domesticus) powder was added to wheat flour to obtain bread with enhanced nutritional value. Bread loaves were obtained from doughs produced using different blends of wheat flour and cricket powder added in amounts of 10 or 30% (based on wheat flour) and baker's yeast and/or sourdough. Raw materials, doughs and breads were subjected to technological, microbiological, chemical and sensory analyses. Overall, a negative linear correlation between the amount of added cricket powder and the dough technological parameters was seen. However, compared to control breads produced with the sole wheat flour, breads containing cricket powder showed a higher nutritional profile in terms of fatty acid composition, high protein content and occurrence of essential amino acids. Finally, bread enriched with 10% cricket powder showed a discrete global liking by untrained panelists. Data overall collected highlighted a good suitability of cricket powder for the production of enriched bread. Of note, the presence of spore-forming bacteria in cricket-based bread loaves, thus highlighting potential safety issues to be deepened. Industrial relevance The present study demonstrated that edible insects powder can successfully be included in leavened baked goods to enhance their protein content. The present research also responds to the growing awareness of consumers towards innovative and wholesome leavened goods, proving that edible insects can constitute a novel source of innovative ingredients to be used in bread making.

Revealing the microbiota of marketed edible insects through PCR-DGGE, metagenomic sequencing and real-time PCR

The present study aimed to identify the microbiota present in six species of processed edible insects produced in Thailand and marketed worldwide via the internet, namely, giant water bugs (Belostoma lutarium), black ants (Polyrhachis), winged termites (alates, Termitoidae), rhino beetles (Hyboschema contractum), mole crickets (Gryllotalpidae), and silkworm pupae (Bombyx mori). For each species, two samples of boiled, dried and salted insects were purchased. The microbial DNA was extracted from the insect samples and subjected to polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), high-throughput sequencing and qualitative real-time PCR assays. The microbiota of the analyzed samples were widely characterized by the presence of spore-forming bacteria mainly represented by the genera Bacillus and Clostridium. Moreover, the genera Anaerobacillus, Paenibacillus, Geobacillus, Pseudomonas, Stenotrophomonas, Massilia, Delftia, Lactobacillus, Staphylococcus, Streptococcus, Vagococcus, and Vibrio were also detected. Real-time PCR allowed for ascertainment of the absence of Coxiella burnetii, Shiga toxin-producing E. coli (STEC), and Pseudomonas aeruginosa in all samples. The results of this study confirm the importance of combining different molecular techniques to characterize the biodiversity of complex ecosystems such as edible insects. The presence of potential human pathogens suggests the need for a careful application of good manufacturing practices during insect processing. This study provides further data that will be useful in risk analyses of edible insects as a novel food source.

Identification and Characterization of Bacteria Isolated from Pipe-borne Water Samples in Selected Areas of Lagos Using Api kits and RAPD-PCR

Pipe-borne water is a major source of drinking water and contamination of such water source could lead to an epidemic. The aim of this present study is to isolate, identify and characterize microorganisms in pipe-borne water in different locations of Lagos metropolis. Six microorganisms were isolated from water samples collected at five locations. The isolates were subjected to morphological as well as biochemical tests using gram staining and Analytical Profile Index (API) tests respectively. Three primers (S gene, RAPD 1 and RAPD 2) were used for the PCR amplification of DNA samples extracted from the isolates and were identified as bacterial species: Bacillus polymyxa, Bacillus alvei, Bacillus mycoides, Pasteurella aerogenes, Pasteurella pneumotropica and Staphylococcus aureus. Gel electrophoresis of the amplified DNA samples generated a total of 128 bands which were subjected to statistical analysis using the NTSYS software (version 2.02j). The results as shown in the UPGMA dendrograms revealed a similarity coefficient of 0.66 among B. polymyxa, B. alvei and B. mycoides as well as a high similarity coefficient of 0.72 between P. pneumotropica and S. aureus. The presence of spore-forming bacteria, B. mycoides B. polymyxa and B. alvei is considered a biohazard as they can survive for long periods while the presence of P. aerogenes, P. pneumotropica and S. aureus, known as opportunistic pathogens is equally hazardous and can be a potential cause of water borne disease. This present study, using RAPD-PCR technique has improved the identification and characterization of microorganisms isolated from pipe-borne water.

Genomic characterization and assessment of the virulence and antibiotic resistance of the novel species Paenibacillus sp. strain VT-400, a potentially pathogenic bacterium in the oral cavity of patients with hematological malignancies.

BackgroundPaenibacillus sp. strain VT-400, a novel spore-forming bacterium, was isolated from patients with hematological malignancies.MethodsPaenibacillus sp. strain VT-400 was isolated from the saliva of four children with acute lymphoblastic leukemia. The genome was annotated using RAST and the NCBI Prokaryotic Genome Annotation Pipeline to characterize features of antibiotic resistance and virulence factors. Susceptibility to antibiotics was determined by the Kirby–Bauer disc diffusion method. We used a mouse model of pneumonia to study virulence in vivo. Mice were challenged with 7.5 log10–9.5 log10 CFU, and survival was monitored over 7 days. Bacterial load was measured in the lungs and spleen of surviving mice 48 h post-infection to reveal bacterial invasion and dissemination.ResultsWhole-genome sequencing revealed a large number of virulence factors such as hemolysin D and CD4+ T cell-stimulating antigen. Furthermore, the strain harbors numerous antibiotic resistance genes, including small multidrug resistance proteins, which have never been previously found in the Paenibacillus genus. We then compared the presence of antibiotic resistance genes against results from antibiotic susceptibility testing. Paenibacillus sp. strain VT-400 was found to be resistant to macrolides such as erythromycin and azithromycin, as well as to chloramphenicol and trimethoprim–sulphamethoxazole. Finally, the isolate caused mortality in mice infected with ≥8.5 log10 CFU.ConclusionsBased on our results and on the available literature, there is yet no strong evidence that shows Paenibacillus species as an opportunistic pathogen in immunocompromised patients. However, the presence of spore-forming bacteria with virulence and antibiotic resistance genes in such patients warrants special attention because infections caused by spore-forming bacteria are poorly treatable.

Iron reduction and gley formation by nitrogen-fixing clostridia.

Studies on iron reduction and the mechanism of gley formation by nitrogen-fixing clostridia are reported. Up to 106 cells/g soil of anaerobic, nitrogen-fixing clostridia, capable of reducing iron (III)-oxide, were counted in samples taken from various top soils. In a gleyed subsoil as many as 105 bacteria per g soil, capable of reducing and fixing nitrogen, were enumerated using the most probable number technique. In general, the ratio of the auxotrophic iron reducing clostridia (glucose+yeast extract fermenters) to the prototrophic iron reducing flora (glucose fermenters) was found much larger in the top soil samples than in those derived from various gleyed subsoils.An enrichment method for the isolation of nitrogen-fixing, iron reducing clostridia of the butyric-butyl type is described. The iron reducing capacity of this type of clostridia as well as of Clostridium pasteurianum was determined quantitatively. Generally, the presence of soil or soil extract enhanced the amount of dissolved ferrous iron, both with butyric acid fermenters and with Cl. pasteurianum.When enriched iron reducing clostridia were incubated anaerobically under N2-atmosphere in a sterile, red-colored, lateritic type of soil with glucose, intense gleying occurred within a few days. Microscopic observations indicated the presence of sporeforming bacteria of the Clostridium butyricum type or related species.The biological and chemical mechanism of gley formation is discussed.