scholarly journals An Alkylpyrazine Synthesis Mechanism Involving L-Threonine-3-Dehydrogenase Describes the Production of 2,5-Dimethylpyrazine and 2,3,5-Trimethylpyrazine by Bacillus subtilis

2019 ◽  
Vol 85 (24) ◽  
Author(s):  
Lijie Zhang ◽  
Yanli Cao ◽  
Jianan Tong ◽  
Yan Xu
Keyword(s):  
Bacillus Subtilis ◽  
Fermented Foods ◽  
Synthesis Mechanism ◽  
Content Type ◽  
Coa Ligase ◽  
Starting Point ◽  
Whole Cell Catalysis ◽  
Ph Dependent ◽  
Traditional Fermented Foods ◽  
Substrate Addition

ABSTRACT Alkylpyrazines are important contributors to the flavor of traditional fermented foods. Here, we studied the synthesis mechanisms of 2,5-dimethylpyrazine (2,5-DMP) and 2,3,5-trimethylpyrazine (TMP). Substrate addition, whole-cell catalysis, stable isotope tracing experiments, and gene manipulation revealed that l-threonine is the starting point involving l-threonine-3-dehydrogenase (TDH) and three uncatalyzed reactions to form 2,5-DMP. TDH catalyzes the oxidation of l-threonine. The product of this reaction is l-2-amino-acetoacetate, which is known to be unstable and can decarboxylate to form aminoacetone. It is proposed that aminoacetone spontaneously converts to 2,5-DMP in a pH-dependent reaction, via 3,6-dihydro-2,5-DMP. 2-Amino-3-ketobutyrate coenzyme A (CoA) ligase (KBL) catalyzes the cleavage of l-2-amino-acetoacetate, the product of TDH, into glycine and acetyl-CoA in the presence of CoA. Inactivation of KBL could improve the production of 2,5-DMP. Besides 2,5-DMP, TMP can also be generated by Bacillus subtilis 168 by using l-threonine and d-glucose as the substrates and TDH as the catalytic enzyme. IMPORTANCE Despite alkylpyrazines' contribution to flavor and their commercial value, the synthesis mechanisms of alkylpyrazines by microorganisms remain poorly understood. This study revealed the substrate, intermediates, and related enzymes for the synthesis of 2,5-dimethylpyrazine (2,5-DMP), which differ from the previous reports about the synthesis of 2,3,5,6-tetramethylpyrazine (TTMP). The synthesis mechanism described here can also explain the production of 2,3,5-trimethylpyrazine (TMP). The results provide insights into an alkylpyrazine’s synthesis pathway involving l-threonine-3-dehydrogenase as the catalytic enzyme and l-threonine as the substrate.

scholarly journals Comparative Genomic and Functional Evaluations of Bacillus subtilis Newly Isolated from Korean Traditional Fermented Foods

Foods ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1805
Author(s):  
Hye Jin Choi ◽  
Donghyun Shin ◽  
Minhye Shin ◽  
Bohyun Yun ◽  
Minkyoung Kang ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Animal Health ◽  
Comparative Genomic ◽  
Fermented Foods ◽  
Immune Gene ◽  
Bacterial Strains ◽  
Isolation And Identification ◽  
Beneficial Effects ◽  
Bacillus Spp ◽  
Traditional Fermented Foods

Many fermented foods are known to have beneficial effects on human and animal health, offering anti-aging and immunomodulatory benefits to host. Microorganisms contained in the fermented foods are known to provide metabolic products possibly improving host health. However, despite of a number of studies on the functional effects of the fermented foods, isolation and identification of the effective bacterial strains in the products are still in progress. The objective of this study was to isolate candidate functional strains in various Korean traditional fermented foods, including ganjang, gochujang, doenjang, and jeotgal, and evaluate their beneficial effects on the host, using Caenorhabditis elegans as a surrogate animal model. Among the 30 strains isolated, five Bacillus spp. were selected that increased the expression level of pmk-1, an innate immune gene of C. elegans. These strains extended the nematode lifespan and showed intestinal adhesion to the host. Based on the bioinformatic analyses of whole genome sequences and pangenomes, the five strains of Bacillus subtilis were genetically different from the strains found in East Asian countries and previously reported strains isolated from Korean fermented foods. Our findings suggest that the newly isolated B. subtilis strains can be a good candidate for probiotic with further in-depth investigation on health benefits and safety.

Adopting traditional fermented foods as carriers for probiotics

2019 ◽  
Vol 50 (5) ◽  
pp. 841-852
Author(s):  
Ivan Muzira Mukisa ◽  
Stellah Byakika ◽  
Rehema Meeme ◽  
Alex Paul Wacoo ◽  
Wilbert Sybesma ◽  
...  
Keyword(s):  
Lactobacillus Rhamnosus ◽  
Streptococcus Thermophilus ◽  
Soluble Solids ◽  
Consumer Acceptability ◽  
Fermented Foods ◽  
Content Type ◽  
Microbial Counts ◽  
Overall Acceptability ◽  
Novel Approach ◽  
Traditional Fermented Foods

Purpose Traditional fermented products can be adopted as probiotic carriers. This study was aimed at evaluating the potential of using Obushera, a traditional sorghum beverage from Uganda, as a carrier for Lactobacillus rhamnosus yoba. Design/methodology/approach Probiotic Obushera was produced by fermenting sorghum malt with Lb. rhamnosus yoba 2012 and Streptococcus thermophilus C106 at 30 °C and at room temperature (21°C-25 °C) for 24 h. Acidity, pH, total soluble solids and microbial counts were monitored. Consumer acceptability and purchase index of probiotic Obushera were compared to four commercial non-probiotic brands. Shelf stability of probiotic Obushera was determined by monitoring changes in pH, acidity, soluble solids, microbial counts and consumer acceptability during refrigerated storage. Findings Lactobacillus rhamnosus yoba 2012 multiplied and lowered the pH of Obushera from 5.3 to < 4.0 (p < 0.0001) whilst increasing acidity from 0.21 to 0.46 per cent (p < 0.0001) in 9 h at 30 °C. Consumer acceptability varied with Obushera brand (p < 0.0001). The overall acceptability score of probiotic Obushera (score of 6.4 = like slightly) was similar to that of the two most acceptable commercial brands (scores of 5.8 and 6.6). Acidity, pH and Lb. rhamnosus counts of probiotic Obushera varied within 0.6 per cent –1.05 per cent (p < 0.0001), 3.3–3.4 (p < 0.0001), and 8.2-9.2 log cfu/ml (p < 0.0001), respectively during two months of storage. The overall acceptability of probiotic Obushera (scores of 6.9-7.8) did not change significantly during storage (p = 0.185). Practical Implications Traditional fermented foods such as Obushera can be adopted as carriers of probiotic microorganisms. Originality/value Use of commercial probiotic strains in traditional fermented foods is a novel approach that can be adopted to improve safety of traditional fermentations and health of consumers.

Worldwide research tendencies on probiotics in food science: 1993 to 2021

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Çisem Bulut Albayrak ◽  
Mustafa Duran
Keyword(s):  
Food Science ◽  
Fermented Foods ◽  
Clear Understanding ◽  
Future Directions ◽  
Content Type ◽  
Probiotic Potential ◽  
Current Trends ◽  
Literature Reviews ◽  
Health Promoting ◽  
Traditional Fermented Foods

PurposeThis study aimed to identify the main and emerging structural patterns in the growth of the literature on probiotic research in food science, analyze current trends and determine gaps and present future projections.Design/methodology/approachA total of 1,301 scientific documents retrieved from Scopus database dated from 1993 to 2021 were analyzed by using bibliometric and scientometric tools.FindingsThe most influencer journals, leading countries and hotspots were identified by scientometric mapping. “Lactic acid bacteria”, “lactobacillus”, “lactobacillus plantarum”, “viability”, “functional foods” and “microencapsulation” were the top keywords that indicate main emerging areas. After a clear understanding of the current situation, future directions can be better projected. Therefore, investigating new probiotic microorganisms with advanced health promoting properties, adapting the new organisms to various food formulations, identifying the probiotic potential of unexplored traditional fermented foods and developing of nondairy probiotic foods can be the studies of the future.Research limitations/implicationsProbiotic concept has been revised during years and valuable knowledge has been accumulated over past decades. The findings demonstrate the development and trends of probiotic related food science researches. This is the first study to address the limitations of prior systematic literature reviews by applying network analysis and guide future works to fill the identified gaps.Originality/valueThe probiotic concept has been revised for years and valuable knowledge has been accumulated. Within the expanding literature, scientometric and bibliometric analysis will provide valuable contribution for identifying the main patterns, analyzing current trends, determining gaps and presenting future projection. This work presents detailed analysis to determine tendencies in probiotic research in food science.

scholarly journals A Novel D-Allulose 3-Epimerase Gene from the Metagenome of a Thermal Aquatic Habitat and D-Allulose Production by Bacillus subtilis Whole-Cell Catalysis

2019 ◽  
Vol 86 (5) ◽  
Author(s):  
Satya Narayan Patel ◽  
Girija Kaushal ◽  
Sudhir P. Singh
Keyword(s):  
Thermal Stability ◽  
Bacillus Subtilis ◽  
Water Reservoir ◽  
Heat Stability ◽  
Thermal Spring ◽  
Hot Water ◽  
Whole Cell ◽  
Content Type ◽  
Extraction And Purification ◽  
Whole Cell Catalysis

ABSTRACT A novel d-allulose 3-epimerase gene (daeM) has been identified from the metagenomic resource of a hot-water reservoir. The enzyme epimerizes d-fructose into d-allulose, a functional sugar of rare abundance in nature. The metagenomic DNA fragment was cloned and expressed in Escherichia coli. The purified recombinant protein (DaeM) was found to be metal dependent (Co2+ or Mn2+). It displayed the maximal levels of catalytic activity in a pH range of 6 to 11 and a temperature range of 75°C to 80°C. The enzyme exhibited remarkably high thermal stability at 60°C and 70°C, with half-life values of 9,900 and 3,240 min, respectively. To the best of our knowledge, this is the highest thermal stability demonstrated by a d-allulose 3-epimerase that has been characterized to date. The enzymatic treatment of 700 mg·ml−1 d-fructose yielded about 217 mg·ml−1 d-allulose, under optimal condition. The catalytic product was purified, and its nuclear magnetic resonance (NMR) spectra were found to be indistinguishable from those of standard d-allulose. For biomolecule production, the whole-cell catalysis procedure avoids the tedious process of extraction and purification of enzyme and also offers better biocatalyst stability. Further, it is desirable to employ safe-grade microorganisms for the biosynthesis of a product. The daeM gene was expressed intracellularly in Bacillus subtilis. A whole-cell catalysis reaction performed with a reaction volume of 1 liter at 60°C yielded approximately 196 g·liter−1 d-allulose from 700 g·liter−1 d-fructose. Further, the whole recombinant cells were able to biosynthesize d-allulose in apple juice, mixed fruit juice, and honey. IMPORTANCE d-Allulose is a noncaloric sugar substitute with antidiabetes and antiobesity potential. With several characteristics of physiological significance, d-allulose has wide-ranging applications in the food and pharmacology industries. The development of a thermostable biocatalyst is an objective of mainstream research aimed at achieving industrial acceptability of the enzyme. Aquatic habitats of extreme temperatures are considered a potential metagenomic resource of heat-tolerant biocatalysts of industrial importance. The present study explored the thermal-spring metagenome of the Tattapani geothermal region, Chhattisgarh, India, discovering a novel d-allulose 3-epimerase gene, daeM, encoding an enzyme of high-level heat stability. The daeM gene was expressed in the microbial cells of a nonpathogenic and safe-grade species, B. subtilis, which was found to be capable of performing d-fructose to d-allulose interconversion via a whole-cell catalysis reaction. The results indicate that DaeM is a potential biocatalyst for commercial production of the rare sugar d-allulose. The study established that extreme environmental niches represent a genomic resource of functional sugar-related biocatalysts.

scholarly journals Oxalate-Degrading Bacillus subtilis Mitigates Urolithiasis in a Drosophila melanogaster Model

mSphere ◽  
2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Kait F. Al ◽  
Brendan A. Daisley ◽  
Ryan M. Chanyi ◽  
Jennifer Bjazevic ◽  
Hassan Razvi ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Bacillus Subtilis ◽  
Calcium Oxalate ◽  
Kidney Stone ◽  
Stone Formation ◽  
Stone Disease ◽  
Fermented Foods ◽  
Content Type ◽  
Kidney Stone Disease

Kidney stone disease is a morbid condition that is increasing in prevalence, with few nonsurgical treatment options. The majority of stones are composed of calcium oxalate. Unlike humans, some microbes can break down oxalate, suggesting that microbial therapeutics may provide a novel treatment for kidney stone patients. This study demonstrated that Bacillus subtilis 168 (BS168) decreased stone burden, improved health, and complemented the microbiota in a Drosophila melanogaster urolithiasis model, while not exacerbating calcium oxalate aggregation or adhesion to renal cells in vitro. These results identify this bacterium as a candidate for ameliorating stone formation; given that other strains of B. subtilis are components of fermented foods and are used as probiotics for digestive health, strain 168 warrants testing in humans. With the severe burden that recurrent kidney stone disease imposes on patients and the health care system, this microbial therapeutic approach could provide an inexpensive therapeutic adjunct.

Research Trend in Traditional Fermented Foods Focused on Health Functional Evaluation

2018 ◽  
Vol 47 (4) ◽  
pp. 373-386 ◽  
Author(s):  
Eun-Gyung Mun ◽  
Bohkyung Kim ◽  
Eun-Young Kim ◽  
Hae-Jeung Lee ◽  
Young Kim ◽  
...  
Keyword(s):  
Research Trend ◽  
Fermented Foods ◽  
Functional Evaluation ◽  
Traditional Fermented Foods

scholarly journals Predicting the Structure and Dynamics of Membrane Protein GerAB from Bacillus subtilis

2021 ◽  
Vol 22 (7) ◽  
pp. 3793
Author(s):  
Sophie Blinker ◽  
Jocelyne Vreede ◽  
Peter Setlow ◽  
Stanley Brul
Keyword(s):  
Bacillus Subtilis ◽  
Membrane Protein ◽  
Spore Germination ◽  
Structural Information ◽  
Transmembrane Protein ◽  
Homology Modelling ◽  
Water Channel ◽  
Md Simulations ◽  
Integral Membrane Protein ◽  
Starting Point

Bacillus subtilis forms dormant spores upon nutrient depletion. Germinant receptors (GRs) in spore’s inner membrane respond to ligands such as L-alanine, and trigger spore germination. In B. subtilis spores, GerA is the major GR, and has three subunits, GerAA, GerAB, and GerAC. L-Alanine activation of GerA requires all three subunits, but which binds L-alanine is unknown. To date, how GRs trigger germination is unknown, in particular due to lack of detailed structural information about B subunits. Using homology modelling with molecular dynamics (MD) simulations, we present structural predictions for the integral membrane protein GerAB. These predictions indicate that GerAB is an α-helical transmembrane protein containing a water channel. The MD simulations with free L-alanine show that alanine binds transiently to specific sites on GerAB. These results provide a starting point for unraveling the mechanism of L-alanine mediated signaling by GerAB, which may facilitate early events in spore germination.

Experience and expression of social isolation by inner-city high-rise residents

2014 ◽  
Vol 17 (3) ◽  
pp. 151-166 ◽  
Author(s):  
Love M. Chile ◽  
Xavier M. Black ◽  
Carol Neill
Keyword(s):  
Older Adults ◽  
Inner City ◽  
Social Isolation ◽  
Age Groups ◽  
Evidence Base ◽  
Structured Interviews ◽  
Content Type ◽  
High Rise ◽  
Starting Point ◽  
Health And Social Care

Purpose – The purpose of this paper is to examine the significance of social isolation and the factors that create social isolation for residents of inner-city high-rise apartment communities. We critically examine how the physical environment and perceptions of safety in apartment buildings and the inner-city implicate the quality of interactions between residents and with their neighbourhood community. Design/methodology/approach – The authors used mixed-methods consisting of survey questionnaires supplemented by semi-structured interviews and focus group discussions using stratified random sampling to access predetermined key strata of inner-city high-rise resident population. Using coefficient of correlation we examine the significance of the association between social isolation, age and ethnicity amongst Auckland's inner-city high-rise residents. Findings – The authors found the experience and expression of social isolation consistent across all age groups, with highest correlation between functional social isolation and “being student”, and older adults (60+ years), length of tenure in current apartment and length of time residents have lived in the inner-city. Research limitations/implications – As a case study, we did not seek in this research to compare the experience and expressions of social isolation in different inner-city contexts, nor of inner-city high-rise residents in New Zealand and other countries, although these will be useful areas to explore in future studies. Practical implications – This study is a useful starting point to build evidence base for professionals working in health and social care services to develop interventions that will help reduce functional social isolation amongst young adults and older adults in inner-city high-rise apartments. This is particularly important as the inner-city population of older adults grow due to international migration, and sub-national shifts from suburbs to the inner-cities in response to governmental policies of urban consolidation. Originality/value – By identifying two forms of social isolation, namely functional and structural social isolation, we have extended previous analysis of social isolation and found that “living alone” or structural social isolation did not necessarily lead to functional social isolation. It also touched on the links between functional social isolation and self-efficacy of older adults, particularly those from immigrant backgrounds.

Role of social networking services for scientists in promoting scientific output on example of Polish representatives of social communication and media sciences

2020 ◽  
Vol 69 (8/9) ◽  
pp. 717-736
Author(s):  
Małgorzata Kowalska-Chrzanowska ◽  
Przemysław Krysiński
Keyword(s):  
Social Networking ◽  
Social Communication ◽  
Scientific Communication ◽  
Scientific Output ◽  
Scientific Publications ◽  
Social Networking Services ◽  
Content Type ◽  
Starting Point ◽  
The Media ◽  
Usage Level

Purpose This paper aims to answer the question of how the Polish representatives of social communication and media sciences communicate the most recent scientific findings in the media space, i.e. what types of publications are shared, what activities do they exemplify (sharing information about their own publications, leading discussions, formulating opinions), what is the form of the scientific communication created by them (publication of reference lists' descriptions, full papers, preprints and post prints) and what is the audience reception (number of downloads, displays, comments). Design/methodology/approach The authors present the results of analysis conducted on the presence of the most recent (2017–2019) publications by the Polish representatives of the widely understood social communication and media sciences in three selected social networking services for scientists: ResearchGate, Google Scholar and Academia.edu. The analyses covered 100 selected representatives of the scientific environment (selected in interval sampling), assigned, according to the OECD classification “Field of Science”, in the “Ludzie nauki” (Men of Science) database to the “media and communication” discipline. Findings The conducted analyses prove a low usage level of the potential of three analysed services for scientists by the Polish representatives of social communication and media sciences. Although 60% of them feature profiles in at least one of the services, the rest are not present there at all. From the total of 113 identified scientists' profiles, as little as 65 feature publications from 2017 to 2019. Small number of alternative metrics established in them, implies, in turn, that if these metrics were to play an important role in evaluation of the value and influence of scientific publications, then this evaluation for the researched Polish representatives of social communication and media sciences would be unfavourable. Originality/value The small presence of the Polish representatives of the communication and media sciences in three analysed services shows that these services may be – for the time being – only support the processes of managing own scientific output. Maybe this quite a pessimistic image of scientists' activities in the analysed services is conditioned by a simple lack of the need to be present in electronic channels of scientific communication or the lack of trust to the analysed services, which, in turn, should be linked to their shortcomings and flaws. However, unequivocal confirmation of these hypotheses might be brought by explorations covering a larger group of scientists, and complemented with survey studies. Thus, this research may constitute merely a starting point for further explorations, including elaboration of good practices with respect to usage of social media by scientists.

Sign in / Sign up

Export Citation Format

Share Document