Secular Trends in Depressive Symptoms in Adolescents in Yunnan, Southwest China From Before COVID-19 to During the COVID-19 Pandemic: Longitudinal, Observational Study.

BACKGROUND: Yunnan province borders Myanmar, Laos, and Vietnam, giving it one of the longest borders in China. We aimed to determine the trends in prevalence and impact of COVID-19 on depressive symptoms among adolescents (12-18 years) from 2018 to 2022 in Yunnan, southwest China. OBJECTIVE: We evaluated the impact of the COVID-19 epidemic on adolescents' mental health, with the aim of reducing the effect of psychological emergency syndrome and promoting healthy, happy adolescent growth. METHODS: This longitudinal, observational study used Students' Health Survey data on adolescents' depressive symptoms from 2018 to 2022 (before and during COVID-19) in Yunnan. We used multistage, stratified sampling in 3 prefectures in 2018 and 16 prefectures from 2019 to 2022. In each prefecture, the study population was classified by gender and residence (urban or rural), and each group was of equal size. Depressive symptoms were diagnosed based on Center for Epidemiological Studies Depression Scale (CES-D) scores. We used ANOVA to assess the differences in mean CES-D scores stratified by gender, age, residence, grade, and ethnicity. Chi-square tests were used to compare depressive symptoms by different variables. For comparability, the age-standard and gender-standard population prevalences were calculated using the 2010 China Census as the standard population. The association between COVID-19 and the risk of a standardized prevalence of depressive symptoms was identified using unconditional logistic regression analysis. RESULTS: The standardized prevalence of depressive symptoms for all participants was 32.98%: 28.26% in 2018, 30.89% in 2019, 29.81% in 2020, 28.77% in 2021, 36.33% in 2022. The prevalences were 30.49% before COVID-19,29.29% in early COVID-19, and 36.33% during the COVID-19 pandemic. Compared with before COVID-19, the risks of depressive symptoms were 0.793 (95% CI 0.772-0.814) times higher in early COVID-19 and 1.071 (95% CI 1.042-1.100) times higher than during COVID-19. The average annual increase in depressive symptoms was 1.61%. During the epidemic, the prevalence of depressive symptoms in girls (36.87%) was higher than that in boys (28.64%), and the acceleration rate of girls was faster than that of boys. The prevalences of depressive symptoms and acceleration rates by age group were as follows: 27.14% and 1.09% (12-13 years), 33.99% and 1.8% (14-15 years), 36.59% and 1.65% (16-18 years). Prevalences did not differ between Han (32.89%) and minority (33.10%) populations. However, the acceleration rate was faster for the former than for the latter. The rate for senior high school students was the highest (34.94%). However, the acceleration rate for vocational high school students was the fastest (2.88%), followed by that for junior high school students (2.32%). Rural residents (35.10%) had a higher prevalence and faster acceleration than urban residents (30.16%). CONCLUSIONS: From 2018 to 2022, there was a significant, continuous increase in the prevalence of depressive symptoms among adolescents in Yunnan, China, especially during the COVID-19 pandemic. This represents an emergency public health problem that should be given more attention. Effective, comprehensive psychological and lifestyle intervention measures should be used to reduce the prevalence of mental health issues in adolescents.

Community medical service construction: identifying factors that influence medical choice for patients with non-communicable chronic diseases in the Southwest China.

BACKGROUND: Community medical institutions play a vital role in China's healthcare system. While the number of these institutions has increased in recent years, their construction contents remain insufficient. The potential of community medical institutions in preventing, screening, diagnosing, and treating non-communicable chronic diseases (NCDs) has not been fully utilized. This study aims to assess the status of construction contents in community medical institutions in Southwest China and examine how these contents influence the medical choices of NCD patients. METHODS: Descriptive statistics were used to evaluate the construction content of community medical institutions. Multiple-sets of multinomial logistic regression were employed to analyze the associations and marginal impacts between construction content and medical choices. Shapley value analysis was applied to determine the contribution and ranking of these impacts. RESULTS: Descriptive statistics revealed satisfactory construction contents in community medical institutions. Notably, factors such as service attitude, nursing services, expert consultations, charging standards, medical equipment, medical examinations, privacy protection, and referrals significantly influenced medical choices. Among these, service attitude, charging standards, and privacy protection had the most significant marginal improvement effects on NCD patients' choices, with improvements of 12.7%, 10.2%, and 5.9%, respectively. The combined contribution of privacy protection, medical examinations, service attitude, charging standards, and nursing services to medical choices exceeded 80%. CONCLUSION: Optimizing the service contents of community institutions can encourage NCD patients to seek medical care at grassroots hospitals. This study addresses crucial gaps in existing literature and offers practical insights for implementing new medical reform policies, particularly in underdeveloped regions of Southwest China focusing on hierarchical diagnosis and treatment.

High-risk population and factors of stroke has changed among middle-aged and elderly Chinese-Evidence from 1989 to 2015.

Background: Stroke is an acute cerebrovascular disease with high mortality and disability. This study aimed to investigate the trend of stroke prevalence from 1989 to 2015 in China, explore the transition of high-risk population and high-risk factors, and provide some evidence to develop more targeted stroke intervention strategies. Material and methods: We derived the baseline data from China Health and Nutrition Survey (CHNS). Participants responded to face-to-face interviews and examinations containing demographic information, behavioral health information, disease history, and physical examination. We applied chi-square test, shapley value decomposition model, and decision tree model to evaluate the changes of high-risk population and high-risk factors of stroke. Results: Across 42,419 middle-aged and elderly residents, the prevalence of stroke was decreasing from 1989 to 2015. Hypertension was the leading risk factor of stroke, while its contribution rate was weakened with the increasing of medicine taking rate. As the second risk factor of stroke, the contribution of age decreased either. Meanwhile, the contribution rate of historical health factors, lifestyle factors, and regional factors, such as body mass index, diabetes, and living area to the impact of stroke was increasing. In addition, the first high-risk population of stroke changed from hypertension patients aged 75 years and above to without spouse residents living in stroke belt such as Beijing and Liaoning. The second risk population of stroke transformed from male hypertensive patients under 75 years old into male hypertensive patients living in urban. The third high-risk group turned from the elderly aged 75 and above into the female patients with hypertension and diabetes. Conclusions: This study demonstrated that the high-risk population and high-risk factors of stroke changed in China and revealed the direction and internal mechanism of transition of stroke. Targeted stroke intervention strategies should be renewed. Health education for the high-risk population of stroke should be carried out, healthy living habits need be advocated, and the use of antihypertensive drugs for the hypertensive patients should be standardized.

A study on the influence of community spiritual comfort service on the mental health of older people.

Background: China is experiencing rapid population aging, with the proportion of older adult people aged 60 and above reaching 19. 8% of the total population in 2022. With the growth of age, the physical function of older adults declines and their mental health is getting worse, with the increasing trend of empty nesting and childlessness, older adults lack information and social interaction with others and fall into social isolation, loneliness and some mental health problems, the proportion of older adults with mental health problems gradually rises and the mortality rate increases incrementally, requiring effective ways to intervene in the mental health of older adults and promote healthy aging. Aim of the study: The present study investigated the influence of spiritual comfort older adult services on the mental health of 12,624 older adults aged 60 years or older in 23 provinces in China from 2017 to 2018, with the aim of providing a case for the development of more targeted mental health strategies for older people. Methods: Using the data from the 2018 CLHLS Survey, the influencing factors of the mental health of older people were analyzed using chi-square test and the logit regression model. The mechanism of the health care facilities and the spiritual comfort services on mental health was analyzed using the chain mediation effect. Results: The spiritual comfort services decreased the risk of negative emotion and mental health of older adults, with female (OR = 1.168), rural residents (OR = 1.385), no drinking (OR = 1.255), not exercising (OR = 1.543), not having pension insurance (OR = 1.233), and low annual household income (OR = 1.416) being the characteristics as risk factors. The mediating effect results showed that the health care facilities had a partial mediating effect between the spiritual comfort services and the mental health status of older people, and the mediating effect accounted for 40.16% of the total effect. Conclusions: The use of spiritual comfort services can effectively reduce and alleviate the adverse mental health symptoms of older people, promote guidance and health education for healthy older people and chronically ill patients, and improve the good health perception of older people in order to improve their quality of life and mental health status.

Secular trends of the prevalence of emaciation, overweight, and obesity among school-aged children in Yunnan province, 1985-2019: A serial cross-sectional surveillance study in China.

Objective: To understand the trends of nutrition in children and adolescents, which may further help to prevent and control chronic diseases in younger ages. Methods: The Chinese National Surveys on Students' Constitution and Health (CNSSCH) in Yunnan is a survey of growth conditions, physical fitness, and health status of students in Yunnan and uses a series of complex multistage stratified sampling of seven prefectures consisting of 16 counties. Sampling schools were held constant over 35 years. The participants were randomly selected among 7-18 aged students. We used data from 1985, 1991, 2000, 2005, 2010, 2014, and 2019 CNSSCH of Yunnan. According to body mass index (BMI) criteria of National Working Group for Obesity in China (WGOC-BMI criteria), a participant's nutrition (emaciation, overweight or obesity) was defined. This study is based on survey data from 129,520 participants in 1985 (n = 14,683), 1991 (n = 4,894), 1995 (n = 6,673), 2000 (n = 9,751), 2005 (n = 23,461), 2010 (n = 22,889), 2014 (n = 23,003) and 2019 (24,166). Results: Since 1985, the trends of emaciation over 35 years were decreasing. Regardless of gender, area, and age, the prevalence of obesity and overweight were increased. The average annual growth rate of overweight and obesity was quicker in rural areas and boys than in urban areas and girls. In Yunnan, emaciation, overweight, and obesity disparity in children were common phenomena, with differences in areas and gender. Conclusion: Children in Yunnan faced the triple burden of malnutrition (emaciation, overweight, and obesity). We should take comprehensive policies and effective intervention measures to decrease the rate of nutrition deficiencies in school-aged children.

Prevalence trends of hypertension and influence factors among children and adolescents aged 7-17 years in China, 2011-2015: A serial cross-sectional study.

Hypertension has rapidly increased in the last decades throughout the world. It is an emerging disease. However, limited information is available on secular trends and factors of childhood and adolescents' hypertension in China. In this study, 5-year successive data were derived from a cross-sectional study of the China Health and Nutrition Survey (CHNS) in 2011 and 2015. We used systolic blood pressure (SBP) and/or diastolic blood pressure (DBP) at least 95th percentile on the basis of age, sex, and height percentiles to define hypertension (HBP). A total of 2,827 children and adolescents aged 7-17 years were included. The age-standardized prevalence of hypertension was increased significantly across 5 years: the standardized prevalence of hypertension was increased from 8.08% (2011) to 11.46% (2015) in China (P < 0.01). The mean SBP of boys increased from 101.21 to 102.79 mmHg, while the mean SBP of girls increased from 98.96 to 100.04 mmHg. The mean DBP of boys increased from 61.20 to 67.40 mmHg, while the mean DBP of girls increased from 64.34 to 65.76 mmHg. The prevalence of hypertension grew continuously in both sexes, but the pace of change for boys was more rapid than that for girls. This study confirmed that the association between rural (odds ratio [OR] = 1.394, 95%CI 1.032-1.883), overweight/obesity (OR = 2.621, 95%CI 1.506-4.562), and BP levels was highly correlated (P < 0.05). The possible protecting factors associated with hypertension were being a girl (OR = 0.788, 95%CI 0.595-1.043). There was no association between weekly physical activity, daily sleep duration, and hypertension (P > 0.05). Further in-depth analysis of influencing factors and comprehensive interventions should be urgently implemented to combat the hypertension epidemic among children and adolescents in China.

Evaluation of stroke health education for primary school students in Dali, China.

Objectives: To provide us with some evidence to develop more targeted stroke intervention strategies, improve the health awareness of stroke among children, and advocate the health promotion campaign of "small hands holding big hands" among parents and children, we have conducted a health education program on stroke among primary school students in Dali. Methods: This study has applied stratified random cluster sampling in Dali of Yunnan, China. We compared the improvement of students' knowledge of stroke before and after our health education program in primary school students of Dali in October 2020. Data were collected through 3 rounds of survey by using the same questionnaire. Results: There were 215 participants aged 7-8 years old sampled in the first phase of the study and 145 participants in the follow-up study. The knowledge of stroke among the participants was relatively low in the pre-intervention survey. After the health education, all the indicators on stroke knowledge were improved. The correct rates in stroke definition, sequelae, and "1-2-0" identification were increased from 0 to 66.05%, to 53.95% and 64.19%, respectively, in both pre-intervention and post-intervention surveys. The correct rate of stroke knowledge was about 4.83-92.41% 3 months after the intervention. The mean score of the questionnaire was 4.25 ± 0.19 in the pre-intervention survey, and that was 15.85 ±0.27 in the post-intervention one. The mean score was 14.02 ± 0.28 post-3-month test. The score in the 3-month survey after the intervention was 11.55% lower than that in the post-intervention score. Conclusions: The effect of stroke-related knowledge in the health education program for children is improved significantly and this can last for 3 months but it also had attenuation. We should repeat pertinent health education among students.

Biodegradation of λ-cyhalothrin through cell surface display of bacterial carboxylesterase.

Pyrethroids are the third widespread used insecticides globally which have been extensively applied in agricultural or household environments. Due to continuous applications, pyrethroids have been detected both in living cells and environments. The permanent exposure to pyrethroids have caused substantial health risks and ecosystem concerns. In this work, a λ-cyhalothrin (one kind of pyrethroid insecticides) degrading bacterium Bacillus velezensis sd was isolated and a carboxylesterase gene, CarCB2 was characterized. A whole cell biocatalyst was developed for λ-cyhalothrin biodegradation by displaying CarCB2 on the surface of Escherichia coli cells. CarCB2 was successfully displayed and functionally expressed on E. coli cells with optimal pH and temperature of 7.5 and 30 °C, using p-NPC4 as substrate, respectively. The whole cell biocatalyst exhibited better stability than the purified CarCB2, and approximately 120%, 60% or 50% of its original activity at 4 °C, 30 °C or 37 °C over a period of 35 d was retained, respectively. No enzymatic activity was detected when incubated the purified CarCB2 at 30 °C for 120 h, or 37 °C for 72 h, respectively. Additionally, 30 mg/L of λ-cyhalothrin was degraded in citrate-phosphate buffer by 10 U of the whole cell biocatalyst in 150 min. This work reveals that the whole cell biocatalyst affords a promising approach for efficient biodegradation of λ-cyhalothrin, and might have the potential to be applied in further environmental bioremediation of other different kinds of pyrethroid insecticides.

Analysis of Saccharification Products of High-Concentration Glutinous Rice Fermentation by Rhizopus nigricans Q3 and Alcoholic Fermentation of Saccharomyces cerevisiae GY-1.

A two-stage process was used to prepare rice alcohol, i.e., saccharification of glutinous rice by Rhizopus nigricans Q3, followed by Saccharomyces cerevisiae's fermentation. Rhizopus nigricans Q3 was cultured during the saccharification stage, and Saccharomyces cerevisiae GY-1 was added in the fermentation stage. Total sugar content and reducing sugar content in these two stages were analyzed. The relationship between the production proportion and consumption of the reducing sugar in the saccharification interval was analyzed using reducing sugar indices. It is an important rule that the high-concentration syrup and oligosaccharides prepared by glutinous rice could reach 42°Bx and 250 mg/mL by high-concentration fermentation in the growth stage of R. nigricans Q3.

Prevalence trends of hypertension among 9-17 aged children and adolescents in Yunnan, 2017-2019: a serial cross-sectional surveillance survey.

BACKGROUND: We aim to describe the prevalence and trends of hypertension among 9-17 school-aged students from 2017 to 2019 in Yunnan, China. METHODS: We conducted a cross-sectional study by using data from the Students' Health Surveillance Surveys of 2017, 2018 and 2019 in Yunnan. The Students' Health Surveillance Surveys in Yunnan collected date on physical fitness and health status of students in Yunnan through multistage-stratified sampling in 3 prefectures. In each prefecture, the study population were classified by gender and region (urban or rural), and each group had an equal size. Diagnosing criteria of hypertension was set with reference to Chinese age-specific and height-specific blood pressure (BP), to identify the abnormal status of boys and girls separately. ANOVA test was adopted to measure the differences in the mean BP stratified by gender, age, prefecture and area, and Chi-square test was used to compare the percentages of hypertension in different areas. For comparability, the age-standard and gender-standard population prevalence was calculated by directly using China Census in 2010 as a standard population. Totally 24,890 participants aged 9-17 years were included in this study. RESULTS: From 2017 to 2019, there were 24,872 students completed physical examinations and included in the analysis, of which 3288 were diagnosed with hypertension. The total prevalence of hypertension was 13.72, 12.49 and 13.45% among 9-17 years school-aged population in Yunnan, respectively. The total age-standardized hypertension prevalence trended to decrease from 13.82 to 13.48%. For urban population, the age-standardized hypertension prevalence decreased slightly from 11.24 to 10.13%. While, for rural population, it increased from 17.58 to 19.16%. The average annual growth rate in rural population was 0.53%. CONCLUSIONS: From 2017to 2019, there was a significant and continuous increase in the prevalence of hypertension in 9-17 years school-aged population in Yunnan. Hypertension is epidemic among children and adolescents in Yunnan. We should take effective and comprehensive intervention measures to reduce its prevalence among school-aged children.

Molecular and Biochemical Characterization of Salt-Tolerant Trehalose-6-Phosphate Hydrolases Identified by Screening and Sequencing Salt-Tolerant Clones From the Metagenomic Library of the Gastrointestinal Tract.

The exploration and utilization of microbial salt-tolerant enzymatic and genetic resources are of great significance in the field of biotechnology and for the research of the adaptation of microorganisms to extreme environments. The presence of new salt-tolerant genes and enzymes in the microbial metagenomic library of the gastrointestinal tract has been confirmed through metagenomic technology. This paper aimed to identify and characterize enzymes that confer salt tolerance in the gastrointestinal tract microbe. By screening the fecal metagenomic library, 48 salt-tolerant clones were detected, of which 10 salt-tolerant clones exhibited stronger tolerance to 7% (wt/vol) NaCl and stability in different concentrations of NaCl [5%-9% (wt/vol)]. High-throughput sequencing and biological information analysis showed that 91 potential genes encoded proteins and enzymes that were widely involved in salt tolerance. Furthermore, two trehalose-6-phosphate hydrolase genes, namely, tre_P2 and tre_P3, were successfully cloned and expressed in Escherichia coli BL21 (DE3). By virtue of the substrate of p-nitrophenyl-α-D-glucopyranoside (pNPG) which can be specifically hydrolyzed by trehalose-6-phosphate hydrolase to produce glucose and p-nitrophenol, the two enzymes can act optimally at pH 7.5 and 30°C. Steady-state kinetics with pNPG showed that the K M and K cat values were 15.63 mM and 10.04 s-1 for rTRE_P2 and 12.51 mM and 10.71 s-1 for rTRE_P3, respectively. Characterization of enzymatic properties demonstrated that rTRE_P2 and rTRE_P3 were salt-tolerant. The enzymatic activity increased with increasing NaCl concentration, and the maximum activities of rTRE_P2 and rTRE_P3 were obtained at 4 and 3 M NaCl, respectively. The activities of rTRE_P2 increased by approximately 43-fold even after 24 h of incubation with 5 M NaCl. This study is the first to report the identification as well as molecular and biochemical characterization of salt-tolerant trehalose-6-phosphate hydrolase from the metagenomic library of the gastrointestinal tract. Results indicate the existence of numerous salt-tolerant genes and enzymes in gastrointestinal microbes and provide new insights into the salt-tolerant mechanisms in the gastrointestinal environment.

Research Article Product Composition Analysis and Process Research of Oligosaccharides Produced from Enzymatic Hydrolysis of High-Concentration Konjac Flour.

There is a huge variability in reducing sugars, viscosity, and composition of oligosaccharides in the hydrolyzed products of konjac flour with different concentrations. We analyzed the factors affecting reducing sugars, viscosity, and the average degree of polymerization (DP) during the preparation of oligosaccharides from konjac flour hydrolyzed by ß-mannanase under the high-concentration solute hydrolysis model. Hydrolysate of konjac flour, using concentrations ranging from 50 to 200 g/L, was directly added into 20 U/mL of ß-mannanase solution. The results showed that when the proportion of the water content in the solution decreased, the viscosity of the solution and the DP of polysaccharides changed significantly. When the viscosity of the hydrolysate was controlled within the range of 30-20 mPa·s, the concentration of the reducing sugars was maintained in the range of 9-13 g/L and the average DP of the polysaccharides was controlled in the range of 2.42-9.78. We also found that a high concentration of hydrolysate was beneficial for decreasing the production of reducing sugars, and the diversification of macromolecular glycan was beneficial to the preparation of functional sugars. Moreover, we observed that the proportion of reducing sugars with free water content was high and that the preparation of oligosaccharides via the high-concentration solid-state method increased product diversity.

Characterization of EstZY: A new acetylesterase with 7-aminocephalosporanic acid deacetylase activity from Alicyclobacillus tengchongensis.

Deacetyl-7-aminocephalosporanic acid (D-7-ACA) is required for producing of many semisynthetic ß-lactam antibiotics; therefore, enzymes capable of converting 7-aminocephalosporanic acid (7-ACA) to D-7-ACA present a valuable resource to the pharmaceutical industry. In the present study, a putative acetylesterase, EstZY, was identified and characterized from a thermophilic bacterium Alicyclobacillus tengchongensis. Sequence alignment showed that EstZY was an acetylesterase which belonged to carbohydrate esterase family 7 (CE7), with substrate preference for short-chain acyl esters p-NPC2 to p-NPC8. Maximum enzyme activity was recorded at pH 9.0 and 50 °C, where Km and Vmax were calculated as 1.9 ± 0.23 mM and 258 ± 18.5 µM min-1, respectively. The residues Ser185, Asp274, and His303 were identified as the putative catalytic triad by homology modelling, site-directed mutagenesis and molecular docking. Moreover, EstZY can remove the acetyl group at C3' position of 7-ACA to form D-7-ACA; this is the first report of a 7-ACA deacetylase from CE7 family in A. tengchongensis and may represent a new enzyme with industrial values.

Identification and characterization of an acetyl esterase from Paenibacillus sp. XW-6-66 and its novel function in 7-aminocephalosporanic acid deacetylation.

OBJECTIVES: To obtain a new acetyl esterase from Paenibacillus sp. XW-6-66 and apply the enzyme to 7-aminocephalosporanic acid (7-ACA) deacetylation. RESULTS: The acetyl esterase AesZY was identified from Paenibacillus sp. XW-6-66, and its enzymatic properties were investigated. With the putative catalytic triad Ser114-Asp203-His235, AesZY belongs to the Acetyl esterase (Aes) family which is included in the α/ß hydrolase superfamily and contains the consensus Gly-X-Ser-X-Gly motif. The maximum activity of AesZY was detected at pH 8.0 and 40 °C. AesZY was stable at different pH values ranging from 5.0 to 12.0, and was tolerant to several metal ions. Furthermore, the deacetylation activity of AesZY toward 7-ACA was approximately 7.5 U/mg, and the Kcat/Km value was 2.04 s-1 mM-1. CONCLUSIONS: Our results demonstrate the characterization of a new acetyl esterase belonging to the Aes family with potential biotechnological applications.

Characterization of a novel salt-, xylose- and alkali-tolerant GH43 bifunctional ß-xylosidase/α-l-arabinofuranosidase from the gut bacterial genome.

A GH43 bifunctional ß-xylosidase encoding gene (XylRBM26) was cloned from Massilia sp. RBM26 and successfully expressed in Escherichia coli. Recombinant XylRBM26 exhibited ß-xylosidase and α-l-arabinofuranosidase activities. When 4-nitrophenyl-ß-d-xylopyranoside was used as a substrate, the enzyme reached optimal activity at pH 6.5 and 50°C and remained stable at pH 5.0-10.0. Purified XylRBM26 presented good salt tolerance and retained 96.6% activity in 3.5 M NaCl and 77.9% initial activity even in 4.0 M NaCl. In addition, it exhibited high tolerance to xylose with Ki value of 500 mM. This study was the first to identify and characterize NaCl-tolerant ß-xylosidase/α-l-arabinofuranosidase from the gut microbiota. The enzyme's salt, xylose, and alkali stability and resistance to various chemicals make it a potential biocatalyst for the saccharification of lignocellulose, the food industry, and industrial processes conducted in sea water.

Application and Analysis of Rhizopus oryzae Mycelia Extending Characteristic in Solid-state Fermentation for Producing Glucoamylase.

Enhanced application of solid-state fermentation (SSF) in industrial production and the influence of SSF of Rhizopus K1 on glucoamylase productivity were analyzed using the flat band method. A growth model was implemented through SSF of Rhizopus K1 in this experiment, and spectrophotometric method was used to determine glucoamylase activity. Results showed that in bran and potato culture medium with 70% moisture in a loose state, µ of mycelium reached to 0.15 h-1 after 45 h of culture in a thermostatic water bath incubator at 30°C. Under a low-magnification microscope, mycelial cells appeared uniform, bulky with numerous branches, and were not easily ruptured. The generated glucoamylase activity reached to 55 U/g (dry basis). This study has good utilization value for glucoamylase production by Rhizopus in SSF.

Enhancing thermal tolerance of Aspergillus niger PhyA phytase directed by structural comparison and computational simulation.

BACKGROUND: Phytase supplied in feeds for monogastric animals is important for improving nutrient uptake and reducing phosphorous pollution. High-thermostability phytases are particularly desirable due to their ability to withstand transient high temperatures during feed pelleting procedures. A comparison of crystal structures of the widely used industrial Aspergillus niger PhyA phytase (AnP) with its close homolog, the thermostable Aspergillus fumigatus phytase (AfP), suggests 18 residues in three segments associated with thermostability. In this work, we aim to improve the thermostability of AnP through site-directed mutagenesis. We identified favorable mutations based on structural comparison of homologous phytases and molecular dynamics simulations. RESULTS: A recombinant phytase (AnP-M1) was created by substituting 18 residues in AnP with their AfP analogs. AnP-M1 exhibited greater thermostability than AnP at 70 °C. Molecular dynamics simulations suggested newly formed hydrogen bonding interactions with nine substituted residues give rise to the improved themostability. Thus, another recombinant phytase (AnP-M2) with just these nine point substitutions was created. AnP-M2 demonstrated superior thermostability among all AnPs at ≥70 °C: AnP-M2 maintained 56% of the maximal activity after incubation at 80 °C for 1 h; AnP-M2 retained 30-percentage points greater residual activity than that of AnP and AnP-M1 after 1 h incubation at 90 °C. CONCLUSIONS: The resulting AnP-M2 is an attractive candidate in industrial applications, and the nine substitutions in AnP-M2 are advantageous for phytase thermostability. This work demonstrates that a strategy combining structural comparison of homologous enzymes and computational simulation to focus on important interactions is an effective method for obtaining a thermostable enzyme.

Mechanical Measurement System and Precision Analysis for Tactile Property Evaluation of Porous Polymeric Materials.

Tactile properties are one of the most important attributes of porous polymeric materials such as textiles, comprising a subjective evaluation index for textile materials and functional clothing, primarily affecting the sensation of comfort during the wearing of a garment. A new test method was proposed, and a mechanical measurement system was developed to objectively characterize the tactile properties of porous polymeric materials by simulating the dynamic contact processes during human skin contact with the materials and in consideration of different aspects of tactile sensations. The measurement system can measure the bending, compression, friction, and thermal transfer properties in one apparatus, and is capable of associating the objective measurements with the subjective tactile sensations. The test and evaluation method, the components of the mechanical measurement system, the definition and grading method of the evaluation indices, and the neural network prediction model from objective test results to subjective sensations of tactile properties were presented. The experiments were conducted for the objective tests and correlation tests. Seven types of porous polymeric sheet materials from seven categories for the tactile properties were cut to a size of 200 mm × 200 mm and tested. Each index of tactile properties was significantly different (P < 0.05) between different sheet materials. The correlations of bending, compression, friction, and thermal transfer properties with Kawabata KES test methods were analyzed. An intra-laboratory test was conducted and an analysis of the variance was performed to determine the critical differences of within laboratory precisions of the measurement system. This mechanical measurement system provides a method and system for objective measurement and evaluation of tactile properties of porous polymeric sheet materials in industrial application.

Genetic diversity of catechol 1,2-dioxygenase in the fecal microbial metagenome.

Catechol 1,2-dioxygenase is the key enzyme that catalyzes the cleavage of the aromatic ring of catechol. We explored the genetic diversity of catechol 1,2-dioxygenase in the fecal microbial metagenome by PCR with degenerate primers. A total of 35 gene fragments of C12O were retrieved from microbial DNA in the feces of pygmy loris. Based on phylogenetic analysis, most sequences were closely related to C12O sequences from Acinetobacter. A full-length C12O gene was directly cloned, heterologously expressed in Escherichia coli, and biochemically characterized. Purified catPL12 had optimum pH and temperature pH 8.0 and 25 °C and retained 31 and 50% of its maximum activity when assayed at 0 and 35 °C, respectively. The enzyme was stable at 25 and 37 °C, retaining 100% activity after pre-incubation for 1 h. The kinetic parameters of catPL12 were determined. The enzyme had apparent Km of 67 µM, Vmax of 7.3 U/mg, and kcat of 4.2 s-1 for catechol, and the cleavage activities for 3-methylcatechol, 4-methylcatechol, and 4-chlorocatechol were much less than for catechol, and no activity with hydroquinone or protocatechuate was detected. This study is the first to report the molecular and biochemical characterizations of a cold-adapted catechol 1,2-dioxygenase from a fecal microbial metagenome.

NaCl-, protease-tolerant and cold-active endoglucanase from Paenibacillus sp. YD236 isolated from the feces of Bos frontalis.

Bos frontalis, which consumes bamboo and weeds, may have evolved unique gastrointestinal microorganisms that digest cellulase. A Paenibacillus sp. YD236 strain was isolated from B. frontalis feces, from which a GH8 endoglucanase gene, pglue8 (1107 bp, 54.5 % GC content), encoding a 368-residue polypeptide (PgluE8, 40.4 kDa) was cloned. PgluE8 efficiently hydrolyzed barley-ß-d-glucan followed by CMC-Na, soluble starch, laminarin, and glucan from black yeast optimally at pH 5.5 and 50 °C, and retained 78.6, 41.6, and 34.5 % maximum activity when assayed at 20, 10, and 0 °C, respectively. Enzyme activity remained above 176.6 % after treatment with 10.0 mM ß-mercaptoethanol, and was 83.0, 78, and 56 % after pre-incubation in 30 % (w/v) NaCl, 16.67 mg/mL trypsin, and 160.0 mg/mL protease K, respectively. Cys23 and Cys364 residues were critical for PgluE8 activity. pglue8, identified from B. frontalis feces for the first time in this study, is a potential alternative for applications including food processing, washing, and animal feed preparation.