Category Archives: Letters in Applied Microbiology

Dynamic changes of bacteria communities in Moutai‐flavour Daqu during storage analysed by next generation sequencing

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Dynamic changes of bacteria communities in Moutai-flavour Daqu during storage analysed by next generation sequencing

Significance and Impact of the Study: Micro-organism is one of the main factors of Moutai-flavour Daqu as a starter. Studying the dynamic changes and differences of micro-organisms in the storage process of Moutai-flavour Daqu in different seasons (spring, summer and autumn) can understand the impact of season and storage time on the micro-organisms in Daqu, which can more scientifically guide the production of Daqu (clarify the storage time in different season), and finally improve the production capacity and quality of Daqu.


Abstract

The quality of Moutai-flavour Baijiu is highly dependent on Moutai-flavour Daqu (MTDQ), which needs to be stored for 6 months before using. It brings abundant bacterium, which can metabolize various enzymes and favour compounds. But the reasonable storage time of MTDQ prepared in different seasons is still uncertain. To this end, the study revealed a detailed bacterial profile of storage MTDQ prepared in three different seasons (specifically, they were stored start from spring, summer and autumn) by using high-throughput sequencing approach (next generation sequencing). Results showed that major phyla of storage MTDQ were Firmicutes, Proteobacteria, Actinobacteria, Bacteroidetes and Fusobacteria. The advantages of Firmicutes were Thermoactinomyces and Bacillaceae. Significant differences in bacterial community structures of MTDQ from different seasons and storage time were observed. Compared with summer and autumn MTDQ, the decrease of Thermoactinomyces and increase of Desmospora in spring MTDQ were the main differences and bacterial community structures of summer and autumn MTDQ were more similar. The variation trends of the bacteria community indicated that the effective time of storage period was appropriately 6 months for spring MTDQ, 2 months for summer MTDQ and more than 6 months for autumn MTDQ. These results showed that the length of storage time was associated with the season and it is reasonable to adjust the storage time of MTDQ with the season.

Ultrasound‐assisted encapsulation of curcumin and fisetin into Saccharomyces cerevisiae cells: a multistage batch process protocol

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Ultrasound-assisted encapsulation of curcumin and fisetin into Saccharomyces cerevisiae cells: a multistage batch process protocol

Significance and Impact of the Study: To the best of our knowledge, this is the first report investigating an ultrasound-assisted batch encapsulation of lipophilic bioactive molecules into Saccharomyces cerevisiae cells. Although ultrasound is a mild, nonthermal, and straightforward cell permeabilization process, few works have investigated it for encapsulation purposes. This study presents a new perspective on the application of ultrasound technology to develop a more economical and eco-friendly process for the food industry, creating a rational way to internalize lipophilic molecules into yeasts via successive stages of encapsulation.


Abstract

Some of the challenges of yeast encapsulation protocols are low phytochemical internalization rates and limited intracellular compartments of yeasts. This study uses an ultrasound-assisted batch encapsulation (UABE) protocol to optimize the encapsulation of curcumin and fisetin by recovering nonencapsulated biomaterial and further incorporating it into nonloaded yeasts in three encapsulation stages (1ES, 2ES and 3ES). The effect of selected acoustic energies (166·7 and 333·3 W l−1) on the encapsulation efficiency (EE), yield (EY) and antioxidant activity retention were evaluated, and then, compared with a control process (without ultrasound treatment). Compared to the control, enhanced EEs were achieved for both curcumin (10·9% control to 58·5% UABE) and fisetin (18·6% control to 76·6% UABE) after 3ES and the use of 333·3 W l−1. Similarly, the yeast maximum loading capacity was improved from 6·6 to 13·4 mg g−1 for curcumin and from 11·1 to 26·4 mg g−1 for fisetin after UABE protocol. The antioxidant activity of produced biocapsules was positively correlated with the bioactive-loaded content of yeasts when ultrasound treatment was applied. Overall, results from this study provide valuable information regarding UABE processes, and moreover, bring new and creative perspectives for ultrasound technology in the food industry.

Molecular mechanisms and clonal lineages of colistin‐resistant bacteria across the African continent: a scoping review

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Molecular mechanisms and clonal lineages of colistin-resistant bacteria across the African continent: a scoping review

Significance and Impact of the Study: Increasing usage of antimicrobial compounds in human and veterinary medicine has contributed to the global emergence and transmission of antimicrobial-resistant bacteria, representing a major concern for human and animal health. According to many international and governmental organizations, the impact of antimicrobial resistance will be particularly significant in low-income regions across Africa, Asia, and Latin America. Accordingly, the development and implementation of multidisciplinary (i.e. One Health) evidence-based control programs and strategies are critical. Colistin is a ‘last-resort’ antimicrobial treatment for multidrug-resistant Gram-negative infections including pneumonia from Enterobacterales; however, high rates of colistin resistance have been reported globally, including Africa. A more profound understanding of the molecular mechanisms underlying colistin resistance is required for the development of effective surveillance programs and innovative therapies against multidrug-resistant bacteria.


Abstract

Colistin (also known as polymyxin E), a polymyxin antibiotic discovered in the late 1940s, has recently reemerged as a last-line treatment option for multidrug-resistant infections. However, in recent years, colistin-resistant pathogenic bacteria have been increasingly reported worldwide. Accordingly, the presented review was undertaken to identify, integrate and synthesize current information regarding the detection and transmission of colistin-resistant bacteria across the African continent, in addition to elucidating their molecular mechanisms of resistance. PubMed, Google Scholar and Science Direct were employed for study identification, screening and extraction. Overall, based on the developed literature review protocol and associated inclusion/exclusion criteria, 80 studies published between 2000 and 2021 were included comprising varying bacterial species and hosts. Numerous mechanisms of colistin resistance were reported, including chromosomal mutation(s) and transferable plasmid-mediated colistin resistance (encoded by mcr genes). Perhaps unexpectedly, mcr-variants have exhibited rapid emergence and spread across most African regions. The genetic variant mcr-1 is predominant in humans, animals and the natural environment, and is primarily carried by IncHI2- type plasmid. The highest number of studies reporting the dissemination of colistin-resistant Gram-negative bacteria were conducted in the North African region.

Campylobacter jejuni and other emerging Campylobacteraceae in retail beef liver – an underestimated potential source?

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Campylobacter jejuni and other emerging Campylobacteraceae in retail beef liver – an underestimated potential source?

Significance and Impact of the Study: Campylobacteraceae has been associated with both intestinal and systemic disease in humans and animals; however, their transmission routes are not entirely clear. Although some species are transmitted by the consumption of chicken or beef meat, other foods such as beef liver have been far less studied. Therefore, this study provides information on retail bovine liver as an underestimated reservoir of diverse Campylobacteraceae, such as Arcobacter butzleri, Campylobacter fetus and Campylobacter coli and its antibiotic resistance profiles. Additionally, the genetic concordance found between Campylobacter jejuni isolates from livers with clinical strains isolated previously in Chile suggests a potential zoonotic relationship.


Abstract

Bovine by-products, such as liver, could be an underestimated source of Campylobacter jejuni. Therefore, our aims were to evaluate the occurrence of C. jejuni and other Campylobacteraceae in retail beef liver and characterize their antibiotic resistance (ciprofloxacin, tetracycline, erythromycin and gentamicin) and potential genetic relationship by flagellin gene restriction fragment length polymorphism (flaA-RFLP) and multilocus sequence typing with clinical strains. Seventy-six out of 206 samples (36·9%) were positive for Campylobacter and related organisms. Arcobacter butzleri was the most frequently isolated species (21·8%), followed by C. jejuni (9·7%), C. fetus (7·8%) and C. coli (1%). The C. jejuni strains showed resistance to tetracycline (17·2%) or ciprofloxacin (6·9%), with only one strain resistant to both antibiotics. Meanwhile, 8·3% of ciprofloxacin resistance was observed in C. fetus. The other species showed no resistance. Most of the clonal complexes (CC) in which the C. jejuni genotypes were grouped (CC-21, 42, 48 and 52), coincided with genotypes of clinical strains previously reported in Chile. As such, this study provides evidence that beef liver could be an underestimated route for resistant C. jejuni to humans. Further studies should assess whether this food could play a role in the transmission of other emerging Campylobacteraceae such as those reported here.

Evaluation of antimicrobial activity of thiolated methylated N‐(4‐N,N‐dimethylaminobenzyl) chitosan as a new derivative of chitosan

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Evaluation of antimicrobial activity of thiolated methylated N-(4-N,N-dimethylaminobenzyl) chitosan as a new derivative of chitosan

Significance and Impact of the Study: Bacterial infection is a major challenge in the world. Using membrane-targeting cationic polymers make an efficient approach for fighting bacterial infection. In this study, thiolated, methylated N-(4-N,N-dimethylaminobenzyl) chitosan polymer showed efficient antimicrobial effects against Gram-positive and Gram-negative bacteria and also against yeast.


Abstract

Despite chitosan, a natural cationic polysaccharide derived from chitin, being applied as an antimicrobial agent, many studies are being performed for enhancing its capability to fight against pathogens. The aim of this study was to investigate the antibacterial effect of thiolated methylated N-(4-N,N-dimethylaminobenzyl) chitosan (TTMAC) polymer and its nanoparticles as a novel derivation of chitosan. The polymer derivative was synthetized and characterized via 1H NMR, Fourier transform infrared and the Elman test. The nanoparticles with different N/P ratios were prepared by the ionic gelation method and were characterized by dynamic light scattering and transmission electron microscopy. The cellular toxicity of polymer and nanoparticles at different concentrations were evaluated on human MCF-7 cell line. Antimicrobial assay was performed on Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923) and Candida albicans (ATCC 10231) as Gram-negative, Gram-positive and yeast pathogens, respectively. The obtained results have shown the TTMAC polymer has a higher inhibition activity against microbial pathogens and also lower cellular toxicity in comparison with chitosan polymer. Furthermore, chitosan nanoparticles in comparison with TTMAC nanoparticles have lower size and highest zeta potential in different ratio and chitosan nanoparticles have more inhibitory effects against microbial pathogens. In conclusion, TTMAC derivative in polymeric form can be a promising tool against microbial pathogens.

Architectural analysis of root system and phytohormone biosynthetic genes expression in wheat (Triticum aestivum L.) inoculated with Penicillium oxalicum

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Architectural analysis of root system and phytohormone biosynthetic genes expression in wheat (Triticum aestivum L.) inoculated with Penicillium oxalicum

Significance and Impact of the Study; Although the impact of microbes on plant growth promotion and root architecture has been widely examined using bacteria, the role of fungi is much less studied. Here, we examined the effect of a potential fungal plant growth promoter Penicillium oxalicum T4 on root architecture and growth of wheat seedlings. Confocal scanning laser micrographs and scanning electron micrographs indicted profuse colonization in wheat roots and induction of root hairs, respectively. Furthermore, P. oxalicum T4 was shown to modulate the expression of host genes related to root growth and development. Overall, P. oxalicum T4 was found to hold promise as a potential microbial formulation for boosting wheat growth.


Abstract

In this study, a fungal plant growth promoter Penicillium oxalicum T4 isolated from non-rhizosphere soil of Arunachal Pradesh, India, was screened for different plant growth promoting traits in a gnotobiotic study. Though inoculation improved the overall growth of the plants, critical differences were observed in root architecture. Confocal Laser Scanning Microscope, Scanning electron microscope and the stereo microscopic study showed that inoculated wheat plants could develop profuse root hairs as compared to control. Root scanning indicated improvement in cumulative root length, root area, root volume, number of forks, links, crossings, and other parameters. A confocal scanning laser microscope indicated signs of endophytic colonization in wheat roots. Gene expression studies revealed that inoculation of T4 modulated the genes affecting root hair development. Significant differences were marked in the expression levels of TaRSL4, TaEXPB1, TaEXPB23, PIN-FORMED protein, kaurene oxidase, lipoxygenase, ACC synthase, ACC oxidase, 9-cis-epoxycarotenoid dioxygenase, and ABA 8′-hydroxylase genes. These genes contribute to early plant development and ultimately to biomass accumulation and yield. The results suggested that P. oxalicum T4 has potential for growth promotion in wheat and perhaps also in other cereals.

Synergistic effects of a functional bacterial consortium on enhancing phenanthrene biodegradation and counteracting rare earth biotoxicity in liquid and slurry systems

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Synergistic effects of a functional bacterial consortium on enhancing phenanthrene biodegradation and counteracting rare earth biotoxicity in liquid and slurry systems

Significance and Impact of the Study: This study focused on the effect of rare earth (REs) on the biodegradation of polycyclic aromatic hydrocarbons (PAHs). The RE ions Ce3+ and Y3+ inhibited Moraxella osloensis CFP312 from degrading phenanthrene without affecting its glucose utilization. This inhibition effect can be relieved through co-cultivation with Bacillus subtilis MSP117, which has high adsorption capacity for RE ions in liquid and slurry systems. MSP117 adsorbed and fixed RE ions on its cell surfaces, thereby reducing the bioavailability of RE ions. This study provides a feasible way for the bioremediation of the co-pollution of RE and organic pollutants.


Abstract

The biodegradation of polycyclic aromatic hydrocarbons (PAHs) by micro-organisms in the environment is often inhibited by coexisting metal ions. The aim of this work is to study a bacterial consortium for enhancing phenanthrene biodegradation under the inhibition effect of the rare earth (RE) ions Ce3+ and Y3+. This bacterial consortium was composed of two bacteria, namely, the RE-adsorbing Bacillus subtilis MSP117 and the phenanthrene-degrading Moraxella osloensis CFP312. Ce3+ and Y3+ at the concentration of 1·15 mmol l−1 inhibited CFP312 from degrading phenanthrene but not glucose. Using glucose as a co-substrate could promote the proliferation of CFP312 but decreased phenanthrene degradation. Adsorption experiments and electron microscopy imaging showed that CFP312 had no RE ions adsorption capacity for RE ions and that RE elements could not be observed on its cell surfaces. MSP117 could adsorb 0·14 and 0·12 mmol g−1 wet cells of Ce3+ and Y3+ in aqueous solution, respectively, thus demonstrating considerable adsorption capacity. The MSP117 cell surface immobilized part of the free RE ions and reduced their bioaccessibility, thereby alleviating their biotoxic effect on phenanthrene degradation by CFP312. In liquid and slurry systems, glucose, which was used as the co-substrate of the bacterial consortium, must be kept at a low level to avoid the catabolism repression of phenanthrene degradation by CFP312.

Characterization of the oral and faecal microbiota associated with atopic dermatitis in dogs selected from a purebred Shiba Inu colony

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Characterization of the oral and faecal microbiota associated with atopic dermatitis in dogs selected from a purebred Shiba Inu colony

Significance and Impact of the Study: The authors investigated the oral and gut microbiota of healthy dogs and dogs with atopic dermatitis using 16S rRNA gene amplicon sequencing in dogs selected from a purebred Shiba Inu colony. The analysis of the microbial diversity, differential abundance and microbial co-occurrence patterns suggested that atopic dermatitis can alter the oral and gut microbiota in dogs.


Abstract

Atopic dermatitis (AD) is a chronic and relapsing multifactorial inflammatory skin disease that also affects dogs. The oral and gut microbiota are associated with many disorders, including allergy. Few studies have addressed the oral and gut microbiota in dogs, although the skin microbiota has been studied relatively well in these animals. Here, we studied the AD-associated oral and gut microbiota in 16 healthy and 9 AD dogs from a purebred Shiba Inu colony. We found that the diversity of the oral microbiota was significantly different among the dogs, whereas no significant difference was observed in the gut microbiota. Moreover, a differential abundance analysis detected the Family_XIII_AD3011_group (Anaerovoracaceae) in the gut microbiota of AD dogs; however, no bacterial taxa were detected in the oral microbiota. Third, the comparison of the microbial co-occurrence patterns between AD and healthy dogs identified differential networks in which the bacteria in the oral microbiota that were most strongly associated with AD were related to human periodontitis, whereas those in the gut microbiota were related to dysbiosis and gut inflammation. These results suggest that AD can alter the oral and gut microbiota in dogs.

Effect of maifan stone on the growth of probiotics and regulation of gut microbiota

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Effect of maifan stone on the growth of probiotics and regulation of gut microbiota

Significance and Impact of the Study: This study explored the influence of Maifan stone-Lacticaseibacillus rhamnosus GG-fermented product in rats with diarrhoea. We found that Maifan stone and the fermented product can reduce the degree of colon pathology in rats to a certain extent, and significantly improve intestinal inflammatory factors and gut microbiota. Therefore, we can reasonably infer that the fermented products are expected to be developed as feed additives, which can replace antibiotics to prevent and treat livestock and poultry intestinal diseases, improve their resistance, reduce feed coefficient, increase feed conversion ratio and improve production performance.


Abstract

Maifan stone is a kind of mineral medicine in Chinese medicine, which has good adsorption, dissolution, mineralization and biological activity. It has an excellent therapeutic effect on livestock, poultry and aquatic animals suffering from intestinal diseases. This study explored the effect of Maifan stone on the growth ability of Lacticaseibacillus rhamnosus GG (L. rhamnosus GG) and the effect of Maifan stone-L. rhamnosus GG-fermented product on the intestinal inflammation and gut microbiota. We find that Maifan stone can adsorb L. rhamnosus GG to form a carrier bacteria. Maifan stone has the characteristics of acid tolerance and bile salt tolerance and can also improve the activity of L. rhamnosus GG in artificial gastrointestinal juice. The fermented product can reduce the degree of diarrhoea and colon pathology in rats to a certain extent and significantly improve intestinal inflammatory factors and gut microbiota. This study improves the application effect of L. rhamnosus GG in the prevention and treatment of diarrhoea animals and provides a scientific basis for the rational development of Maifan stone resources.