Characterization and application of Bacillus velezensis D6 co-producing α-amylase and protease.

BACKGROUND: Research on the co-production of multiple enzymes by Bacillus velezensis as a novel species is still a topic that needs to be studied. This study aimed to investigate the fermentation characteristics of B. velezensis D6 co-producing α-amylase and protease and to explore their enzymatic properties and applications in fermentation. RESULTS: The maximum co-production of α-amylase and protease reached 13.13 ± 0.72 and 2106.63 ± 64.42 U mL-1, respectively, under the optimal fermented conditions (nutrients: 20.0 g L-1 urea, 20.0 g L-1 glucose, 0.7 g L-1 MnCl2; incubation conditions: initial pH 7.0, temperature 41 °C, 8% inoculation size and 30% working volume). Moreover, the genetic co-expression of α-amylase and protease increased from 0 to 24 h and then decreased after 36 h at the transcriptional level, which coincided with the growth trend of B. velezensis D6. The optimal reaction temperature of α-amylase was 55-60 °C, while that of protease was 35-40 °C. The activities of α-amylase and protease were retained by over 80% after thermal treatment (90 °C, 1 h), which indicated that two enzymes co-produced by B. velezensis D6 demonstrated excellent thermal stability. Moreover, the two enzymes were stable over a wide pH range (pH 4.0-8.0 for α-amylase; pH 4.0-9.0 for protease). Finally, the degrees of hydrolysis of corn, rice, sorghum and soybeans by α-amylase from B. velezensis D6 reached 44.95 ± 2.95%, 57.16 ± 2.75%, 52.53 ± 4.01% and 20.53 ± 2.42%, respectively, suggesting an excellent hydrolysis effect on starchy raw materials. The hydrolysis degrees of mackerel heads and soybeans by protease were 43.93 ± 2.19% and 26.38 ± 1.72%, respectively, which suggested that the protease from B. velezensis D6 preferentially hydrolyzed animal-based protein. CONCLUSION: This is a systematic study on the co-production of α-amylase and protease by B. velezensis D6, which is crucial in widening the understanding of this species co-producing multi-enzymes and in exploring its potential application. © 2024 Society of Chemical Industry.

Investigation of bioactive compounds and their correlation with the antioxidant capacity in different functional vinegars.

There are complex and diverse substances in traditional vinegars, some of which have been identified as biologically active factors, but the variety of functional compounds is currently restricted. In this study, it was aimed to determine the bioactive compounds in 10 typical functional vinegars. The findings shown that total flavonoids (0.21-7.19 mg rutin equivalent/mL), total phenolics (0.36-3.20 mg gallic acid equivalent/mL), and antioxidant activities (DPPH: 3.17-47.63 mmol trolox equivalent/L, ABTS: 6.85-178.29 mmol trolox equivalent/L) varied among different functional vinegars. In addition, the concentrations of the polysaccharides (1.17-44.87 mg glucose equivalent/mL) and total saponins (0.67-12.46 mg oleanic acid equivalent/mL) were determined, which might play key role for the function of tested vinegars. A total of 8 organic acids, 7 polyphenol compounds and 124 volatile compounds were measured and tentatively identified. The protocatechuic acid (4.81-485.72 mg/L), chlorogenic acid (2.69-7.52 mg/L), and epicatechin (1.18-97.42 mg/L) were important polyphenol compounds in the functional vinegars. Redundancy analysis indicated that tartaric acid, oxalic acid and chlorogenic acid were significantly positively correlated with antioxidant capacity. Various physiologically active ingredients including cyclo (Pro-Leu), cyclo (Phe-Pro), cyclo (Phe-Val), cyclo (Pro-Val), 1-monopalmitin and 1-eicosanol were firstly detected in functional vinegars. Principle component analysis revealed that volatiles profile of bergamot Monascus aromatic vinegar and Hengshun honey vinegar exhibited distinctive differences from other eight vinegar samples. Moreover, the partial least squares regression analysis demonstrated that 11 volatile compounds were positively correlated with the antioxidant activity of vinegars, which suggested these compounds might be important functional substances in tested vinegars. This study explored several new functionally active compounds in different functional vinegars, which could widen the knowledge of bioactive factor in vinegars and provide new ideas for further development of functional vinegar beverages.

Microbiota stratification and succession of amylase-producing Bacillus in traditional Chinese Jiuqu (fermentation starters).

BACKGROUND: Jiuqu are vital saccharifying and fermenting agents for Chinese fermented foods. Natural ventilation during Jiuqu fermentation causes changes in temperature, oxygen and moisture content, resulting in mass and heat gradients from the outer to inner areas of Jiuqu blocks. In the present study, microbiota stratification in Jiuqu was investigated by single molecule real-time sequencing and culture isolation. The contributors of Bacillus to amylase activity of Jiuqu and the dynamics of their biomass during Jiuqu fermentation were also analyzed. RESULTS: The dominant orders, genera and species between the inner and outer layers of Huangjiu qu (HJQ) were similar, although they displayed greater variance in two layers of Baijiu qu (BJQ). Bacillus possessed the highest diversity (including 27 species) in Jiuqu. Bacillus licheniformis, Bacillus altitudinis, Bacillus subtilis, Bacillus amyloliquefaciens and Bacillus megaterium were most prevalent in HJQ, whereas B. licheniformis, B. amyloliquefaciens and Bacillus cereus were dominant in BJQ. Isolates of B. amyloliquefaciens, B. subtilis and B. cereus exhibited high activities of amylase and glucoamylase. Quantification of Bacillus members possessing genes of α-amylase revealed that B. cereus and B. licheniformis were the most dominant microbes to secret α-amylase in Jiuqu and their biomass were increasing during Jiuqu fermentation. CONCLUSION: The present study demonstrates the microbial distribution in different layers of Jiuqu and clarifies the Bacillus species processing the activity of α-amylase. These results will help industries control the quality of Jiuqu by rationally selecting starters and optimizing their microbiota. © 2020 Society of Chemical Industry.

Microbial ecology of cereal vinegar fermentation: insights for driving the ecosystem function.

Over thousands of years, humans have mastered the natural vinegar fermentation technique of cultivating functional microbiota on different raw materials. Functional microbial communities that form reproducibly on non-autoclaved raw materials through repeated batch acetic acid fermentation underpin the flavour development of traditional cereal vinegars. However, how to modulate rationally and optimise the metabolic function of these naturally engineered acidic ecosystems remains unclear. Exploring two key minorities in a vinegar ecosystem, including microbial functions (e.g., flavour and aroma synthesis) and microbial strains, is a crucial step for the vinegar industry to modulate the metabolic function of vinegar microbiota, to monitor the fermentation process, and to maintain the flavour quality of final product.

Metagenomics reveals flavour metabolic network of cereal vinegar microbiota.

Multispecies microbial community formed through centuries of repeated batch acetic acid fermentation (AAF) is crucial for the flavour quality of traditional vinegar produced from cereals. However, the metabolism to generate and/or formulate the essential flavours by the multispecies microbial community is hardly understood. Here we used metagenomic approach to clarify in situ metabolic network of key microbes responsible for flavour synthesis of a typical cereal vinegar, Zhenjiang aromatic vinegar, produced by solid-state fermentation. First, we identified 3 organic acids, 7 amino acids, and 20 volatiles as dominant vinegar metabolites. Second, we revealed taxonomic and functional composition of the microbiota by metagenomic shotgun sequencing. A total of 86 201 predicted protein-coding genes from 35 phyla (951 genera) were involved in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of Metabolism (42.3%), Genetic Information Processing (28.3%), and Environmental Information Processing (10.1%). Furthermore, a metabolic network for substrate breakdown and dominant flavour formation in vinegar microbiota was constructed, and microbial distribution discrepancy in different metabolic pathways was charted. This study helps elucidating different metabolic roles of microbes during flavour formation in vinegar microbiota.

Exploring flavour-producing core microbiota in multispecies solid-state fermentation of traditional Chinese vinegar.

Multispecies solid-state fermentation (MSSF), a natural fermentation process driven by reproducible microbiota, is an important technique to produce traditional fermented foods. Flavours, skeleton of fermented foods, was mostly produced by microbiota in food ecosystem. However, the association between microbiota and flavours and flavour-producing core microbiota are still poorly understood. Here, acetic acid fermentation (AAF) of Zhenjiang aromatic vinegar was taken as a typical case of MSSF. The structural and functional dynamics of microbiota during AAF process was determined by metagenomics and favour analyses. The dominant bacteria and fungi were identified as Acetobacter, Lactobacillus, Aspergillus, and Alternaria, respectively. Total 88 flavours including 2 sugars, 9 organic acids, 18 amino acids, and 59 volatile flavours were detected during AAF process. O2PLS-based correlation analysis between microbiota succession and flavours dynamics showed bacteria made more contribution to flavour formation than fungi. Seven genera including Acetobacter, Lactobacillus, Enhydrobacter, Lactococcus, Gluconacetobacer, Bacillus and Staphylococcus were determined as functional core microbiota for production of flavours in Zhenjiang aromatic vinegar, based on their dominance and functionality in microbial community. This study provides a perspective for bridging the gap between the phenotype and genotype of ecological system, and advances our understanding of MSSF mechanisms in Zhenjiang aromatic vinegar.

Batch-to-batch uniformity of bacterial community succession and flavor formation in the fermentation of Zhenjiang aromatic vinegar.

Solid-state fermentation of traditional Chinese vinegar is a mixed-culture refreshment process that proceeds for many centuries without spoilage. Here, we investigated bacterial community succession and flavor formation in three batches of Zhenjiang aromatic vinegar using pyrosequencing and metabolomics approaches. Temporal patterns of bacterial succession in the Pei (solid-state vinegar culture) showed no significant difference (P > 0.05) among three batches of fermentation. In all the batches investigated, the average number of community operational taxonomic units (OTUs) decreased dramatically from 119 ± 11 on day 1 to 48 ± 16 on day 3, and then maintained in the range of 61 ± 9 from day 5 to the end of fermentation. We confirmed that, within a batch of fermentation process, the patterns of bacterial diversity between the starter (took from the last batch of vinegar culture on day 7) and the Pei on day 7 were similar (90%). The relative abundance dynamics of two dominant members, Lactobacillus and Acetobacter, showed high correlation (coefficient as 0.90 and 0.98 respectively) among different batches. Furthermore, statistical analysis revealed dynamics of 16 main flavor metabolites were stable among different batches. The findings validate the batch-to-batch uniformity of bacterial community succession and flavor formation accounts for the quality of Zhenjiang aromatic vinegar. Based on our understanding, this is the first study helps to explain the rationality of age-old artistry from a scientific perspective.

[Expression of c-kit and Cx43 in neonates with spontaneous gastric perforation].

OBJECTIVE: To study the clinical significance of interstitial cell of Cajal (ICC) in spontaneous neonatal gastric perforation by examining the expression of c-kit and Cx43 in neonates with this disorder. METHODS: The gastric specimens of 19 cases of neonatal gastric perforation from 2001 to 2010 and 8 cases of accidental death without digestive tract malformations (control) were collected. Immunohistochemical staining was employed to examine the expression of c-kit and Cx43 (immunomarkers of ICCs) in gastric tissues. RESULTS: The muscular layer of the stomach wall became thinner or deficient in the gastric perforation group. C-kit and Cx43 positive cells in gastric tissues decreased significantly in the gastric perforation group compared with those in the control group (P＜0.01). CONCLUSIONS: The development of spontaneous neonatal gastric perforation is associated with the decreased quantity of ICCs and damaged gap junction structure of the stomach wall.

[Clinicopathological characteristics and potential etiologies of neonatal spontaneous gastric perforation].

OBJECTIVE: To study the etiology and clinicopathological features of neonatal spontaneous gastric perforation. METHODS: The clinical data of 15 cases with neonatal gastric perforation seen from 2001 to 2009 were retrospectively analyzed. Immunohistochemical staining was adopted for all the cases. RESULTS: The typical clinical manifestations of this disease were vomiting, abdominal distention and respiratory distress. Abdominal orthostatic X-ray showed free gas under diaphragm and seroperitoneum. In most of the cases the stomach perforation occurred at the greater curvature. Eight of the cases died in this group, the mortality was 53.33%. Six of the deaths occurred within 1 day after birth with symptoms. There were thinning and defect of stomach wall muscle and interstitial cells of Cajal (ICC) reduction as demonstrated by microscope. CONCLUSIONS: Spontaneous neonatal gastric perforation is associated with abnormal gastric wall structure and reduction of ICC. Prognosis is closely related to the time of onset and the timely surgical operation.

[Dynamic analysis of ecological footprint of Dongying City based on a modified model].

Taking the spatiotemporal heterogeneity of water-heat condition into consideration, the traditional ecological footprint (EF) model was modified with net primary productivity (NPP). In the meanwhile, water resource EF was calculated to complement the deficiency of water EF account which only included water's fishing function. The EF dynamics of Dongying City from 1996 to 2003 was analyzed by using the modified model. Based on traditional model, the EF of Dongying City in 1996-2003 increased from 1.766 hm2 to 2.644 hm2, and the ecological capacity (EC) decreased from 0.889 hm2 to 0.813 hm2; while based on the modified model, the EF increased from 2.819 hm2 to 3.776 hm2, and the EC decreased from 1.935 hm2 to 1.865 hm2. Comparing with that from traditional model, the ecological pressure calculated by the modified model was lesser, which suggested that to increase the utilization of water resource would alleviate the ecological pressure on the region. The modified EF model was more precise to reflect the natural resource utilization of Dongying City.

Assay of gastrin and somatostatin in gastric antrum tissues of children with chronic gastritis and duodenal ulcer.

AIM: To study the expressions of gastrin (GAS) and somatostatin (SS) in gastric antrum tissues of children with chronic gastritis and duodenal ulcer and their role in pathogenic mechanism. METHODS: Specimens of gastric antrum mucosa from 83 children were retrospectively analyzed. Expressions of GAS and SS in gastric antrum tissues were assayed by the immunohistochemical En Vision method. RESULTS: The expressions of GAS in chronic gastritis Hp+ group (group A), chronic gastritis Hp-group (group B), the duodenal ulcer Hp+group (group C), duodenal ulcer Hp-group (group D), and normal control group (group E) were 28.50+4.55, 19.60+2.49, 22.69+2.71, 25.33+4.76, and 18.80+2.36, respectively. The value in groups A-D was higher than that in group E. The difference was not statistically significant. The expressions of SS in groups A-E were 15.47+1.44, 17.29+2.04, 15.30+1.38, 13.11+0.93 and 12.14+1.68, respectively. The value in groups A-D was higher than that in group E. The difference was also not statistically significant. CONCLUSION: The expressions of GAS and SS are increased in children with chronic gastritis and duodenal ulcer.

[Expression of gastrin, somatostatin, PCNA and Fas-L in the mucosa of gastric antrum of children with chronic gastritis and duodenal ulcer].

OBJECTIVE: Since application of pediatric gastroscopy in the mid-nineteen nineties, there has been a trend that the prevalence rates of pediatric gastritis and duodenal ulcer (DU) are increasing. The diagnosed rate of pediatric gastritis has accounted for 85% - 95% of the total number of children who received gastroscopy, and the rate of DU accounted for 8% - 22%. Such a high rates of the diseases may influence the development of the children severely. However, the etiology and pathogenesis of pediatric chronic gastritis and DU have not been completely elucidated. The disordered gastrointestinal hormones play a crucial role in the pediatric chronic gastritis and DU. This study focused on the expression of gastrin (GAS), somatostatin (SS) in the mucosa of gastric antrum and PCNA and Fas-L in the sinus ventriculi and their possible roles in the pathogenesis of pediatric chronic gastritis and DU. METHOD: The sinus ventriculi mucosal samples of 83 cases were collected via gastroscopic biopsy from the hospital during the recent two years and the cases were divided into five groups: group A, chronic superficial gastritis, Helicobacter pylori (Hp)(+); group B, chronic superficial gastritis, Hp(-); group C, DU, Hp(+); Group D, DU, Hp(-); Group E, normal sinus ventriculi mucosa, Hp(-). Immunohistochemical staining (En Vision) was carried out for GAS, SS, PCNA and Fas-L, and positive cells of each slide were counted (x 400). Statistically significant differences among groups for continuous data were assessed with the software SPSS10.0. RESULTS: The expressions of GAS and SS in the groups A through E had no significant difference. The expression of PCNA in group A was significantly higher than that in group B (P < 0.05), and no significant differences were found among the other groups. There were no significant differences in expressions of Fas-L among the five groups. CONCLUSION: There seems to be an increasing tendency in the expressions of GAS and SS in children with chronic gastritis and duodenal ulcer. Hp infection promotes the multiplication of the sinus ventriculi mucosal epithelium cells in the pediatric chronic gastritis.

[Expression and pathological implication of transforming growth factor-beta1 mRNA and endothelin-1 mRNA in intraacinar pulmonary arterioles of congenital heart disease accompanied with pulmonary hypertension].

OBJECTIVE: To study the expression and pathological implication of transforming growth factor-1 (TGF-1) and endothelin-1 (ET-1) in intraacinar pulmonary arterioles of children with congenital heart disease and pulmonary hypertension (HP). METHODS: Forty-one children with left-to-right shunt congenital heart disease were studied including 25 cases of HP (group A), 16 cases without HP (group B) and 10 children without congenital heart disease as the contols (group C). Expression of TGF-beta1 mRNA and ET-1 mRNA in intraacinar pulmonary arteriolar (IAPA) was studied using in-situ hybridization and image pattern analysis of their absorption values (A value). Changes of the intraacinar arterioles and lung tissue were studied by elastic fiber staining and electronic microscopy respectively. RESULTS: (1) There was a significant difference in the amount of intraacinar pulmonary arterioles (partial-muscular and muscular) counted in either group A or B in comparing with that of group C (F values 149.96 and 142.01 respectively, P < 0.01); (2) Electronic microscopy demonstrated endothelial proliferation of the small arteries, thickening of arteriolar wall, increased density of collagen fibers at adventitia and increased thickness of the capillary basal membrane; (3) The A value of TGF-beta1 mRNA expressed in the pulmonary arterioles of groups A and B by in-situ hybridization were 0.1988 +/- 0.0498 and 0.1098 +/- 0.0428 respectively, however, the expression was weak in group C (A value: 0.0578 +/- 0.0096). There were all significant between each two groups (F = 45.95, P < 0.01). The expression of ET-1 mRNA was markedly increased as well in the endothelial cells of pulmonary arterioles in both groups A and B, with A values of 0.1692 +/- 0.0205 and 0.1004 +/- 0.0140 respectively, whereas the expression was weak in group C (A value of 0.0746 +/- 0.0119). There were all significant between each two groups (F = 139.996, P < 0.01). CONCLUSIONS: The number of intraacinar pulmonary partial-muscular and muscular arterioles in patients with left-to-right shunt congenital heart defect is drastically increased, along with marked restructuring of the pulmonary vasculatures. In addition, there seems a correlation present between the overexpression of TGF-beta1 mRNA and ET-1 mRNA in intraacinar pulmonary arterioles and the occurrence of pulmonary hypertension in patients with congenital heart disease.