Perinatal prevalence of birth defects in the Mainland of China, 2000-2021: a systematic review and meta-analysis.

BACKGROUND: Although birth defects are of great concern globally, the latest national prevalence has not yet been quantified in China. We conducted a systematic review and meta-analysis to estimate the perinatal prevalence of birth defects in the Mainland of China between 2000 and 2021. METHODS: We performed a systematic literature search of six databases for relevant articles published between January 1, 2000, and March 1, 2023. We included published studies that reported data on the perinatal prevalence of birth defects in the Mainland of China. The DerSimonian and Laird random-effects models were used to estimate the pooled prevalence and its 95% confidence interval (CI). We also conducted subgroup analyses and univariable meta-regressions to explore differences in prevalence by time period, geographic region, and other characteristics. RESULTS: We included 254 studies reporting the perinatal prevalence of birth defects and 86 studies reporting only the prevalence of specific types of birth defects. Based on 254 studies covering 74,307,037 perinatal births and 985,115 cases with birth defects, the pooled perinatal prevalence of birth defects was 122.54 (95% CI 116.20-128.89) per 10,000 perinatal births in the Mainland of China during 2000-2021. Overall, the perinatal prevalence of birth defects increased from 95.60 (86.51-104.69) per 10,000 in 2000-2004 to 208.94 (175.67-242.22) per 10,000 in 2020-2021. There were also significant disparities among different geographical regions. Congenital heart defects (33.35 per 10,000), clefts of the lip and/or palate (13.52 per 10,000), polydactyly (12.82 per 10,000), neural tube defects (12.82 per 10,000), and inborn errors of metabolism (11.41 per 10,000) were the five most common types of birth defects. The perinatal prevalence among males was significantly higher than that among females (ß = 2.44 × 10-3, P = 0.003); a higher perinatal prevalence of birth defects was observed among perinatal births whose mothers were ≥ 35 years (ß = 4.34 × 10-3, P < 0.001). CONCLUSION: Comprehensive and sustained efforts are needed to strengthen surveillance and detection of birth defects, improve prenatal and postnatal healthcare, and promote rehabilitation, especially in underdeveloped areas.

Change from low to out-of-season epidemics of influenza in China during the COVID-19 pandemic: A time series study.

Nonpharmaceutical interventions to limit the coronavirus disease 2019 (COVID-19) pandemic might reduce the transmission of influenza viruses and disrupt the typical seasonality of influenza. However, changes in epidemiology and seasonal patterns of influenza remain unknown in China during the COVID-19 pandemic. Data on influenza-like illness (ILI) and influenza cases between surveillance Week 14 in 2010 and Week 6 in 2023 and ILI outbreaks between Week 14 in 2013 and Week 6 in 2023 were collected from the weekly reports of the Chinese National Influenza Center. A total of 32 10 735 ILI specimens were tested between Week 14 in 2010 and Week 6 in 2023 in China, with 12.4% of specimens positive for influenza. The influenza-positive percentage ranged from 11.8% to 21.1% in southern China and 9.5% to 19.5% in northern China between the 2010/2011 and 2019/2020 influenza seasons. The influenza-positive percentage was 0.7% in southern China and 0.2% in northern China in the 2020/2021 season. An increasing trend in influenza-positive percentage was observed in southern China in Weeks 18-27 in the 2022/2023 season, with a peak of 37.3%. A total of 768 ILI outbreaks reported in southern China in Weeks 14-26 in the 2022/2023 season were much more than those in the same period in the 2020/2021 and 2021/2022 seasons. In summary, seasonal influenza shifted from low to out-of-season epidemics during the COVID-19 pandemic in China, especially in southern China. Influenza vaccination and everyday preventive actions, such as mask wearing, appropriate air exchange, and good hand hygiene practices, are essential for the prevention of influenza virus infection during the COVID-19 pandemic.

Poly(I:C)-induced maternal immune activation causes elevated self-grooming in male rat offspring: Involvement of abnormal postpartum static nursing in dam.

Introduction: Maternal immune activation (MIA) is closely related to the onset of autism-like behaviors in offspring, but the mechanism remains unclear. Maternal behaviors can influence offspring's development and behaviors, as indicated in both human and animal studies. We hypothesized that abnormal maternal behaviors in MIA dams might be other factors leading to delayed development and abnormal behaviors in offspring. Methods: To verify our hypothesis, we analyzed poly(I:C)-induced MIA dam's postpartum maternal behavior and serum levels of several hormones related to maternal behavior. Pup's developmental milestones and early social communication were recorded and evaluated in infancy. Other behavioral tests, including three-chamber test, self-grooming test, open field test, novel object recognition test, rotarod test and maximum grip test, were performed in adolescence of pups. Results: Our results showed that MIA dams exhibit abnormal static nursing behavior but normal basic care and dynamic nursing behavior. The serum levels of testosterone and arginine vasopressin in MIA dams were significantly reduced compared with control dams. The developmental milestones, including pinna detachment, incisor eruption and eye opening, were significantly delayed in MIA offspring compared with control offspring, while the weight and early social communication showed no significant differences between the two groups. Behavioral tests performed in adolescence showed that only male MIA offspring display elevated self-grooming behaviors and reduced maximum grip. Discussion: In conclusion, MIA dams display abnormal postpartum static nursing behavior concomitantly with reduced serum levels of testosterone and arginine vasopressin, possibly involving in the pathogenesis of delayed development and elevated self-grooming in male offspring. These findings hint that improving dam's postpartum maternal behavior might be a potential regime to counteract delayed development and elevated self-grooming in male MIA offspring.

Application of weighted gene co-expression network and immune infiltration for explorations of key genes in the brain of elderly COVID-19 patients.

Introduction: Although many studies have demonstrated the existing neurological symptoms in COVID-19 patients, the mechanisms are not clear until now. This study aimed to figure out the critical molecular and immune infiltration situations in the brain of elderly COVID-19 patients. Methods: GSE188847 was used for the differential analysis, WGCNA, and immune infiltration analysis. We also performed GO, KEGG, GSEA, and GSVA for the enrich analysis. Results: 266 DEGs, obtained from the brain samples of COVID-19 and non-COVID-19 patients whose ages were over 70 years old, were identified. GO and KEGG analysis revealed the enrichment in synapse and neuroactive ligand-receptor interaction in COVID-19 patients. Further analysis found that asthma and immune system signal pathways were significant changes based on GSEA and GSVA. Immune infiltration analysis demonstrated the imbalance of CD8+ T cells, neutrophils, and HLA. The MEpurple module genes were the most significantly different relative to COVID-19. Finally, RPS29, S100A10, and TIMP1 were the critical genes attributed to the progress of brain damage. Conclusion: RPS29, S100A10, and TIMP1 were the critical genes in the brain pathology of COVID-19 in elderly patients. Our research has revealed a new mechanism and a potential therapeutic target.

Duration of viable virus shedding and polymerase chain reaction positivity of the SARS-CoV-2 Omicron variant in the upper respiratory tract: a systematic review and meta-analysis.

OBJECTIVES: To assess the duration of viable virus shedding and polymerase chain reaction (PCR) positivity of the SARS-CoV-2 Omicron variant in the upper respiratory tract. METHODS: We systematically searched PubMed, Cochrane, and Web of Science for original articles reporting the duration of viable virus shedding and PCR positivity of the SARS-CoV-2 Omicron variant in the upper respiratory tract from November 11, 2021 to December 11, 2022. This meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered with PROSPERO (CRD42022357349). We used the DerSimonian-Laird random-effects meta-analyses to obtain the pooled value and the 95% confidence intervals. RESULTS: We included 29 studies and 230,227 patients. The pooled duration of viable virus shedding of the SARS-CoV-2 Omicron variant in the upper respiratory tract was 5.16 days (95% CI: 4.18-6.14), and the average duration of PCR positivity was 10.82 days (95% CI: 10.23-11.42). The duration of viable virus shedding and PCR positivity of the SARS-CoV-2 Omicron variant in symptomatic patients was slightly higher than that in asymptomatic patients, but the difference was not significant (P >0.05). CONCLUSION: The current study improves our understanding of the status of the literature on the duration of viable virus shedding and PCR positivity of Omicron in the upper respiratory tract. Our findings have implications for pandemic control strategies and infection control measures.

Regeneration of NCM622 from end-of-life lithium-ion battery cathode materials.

The boom of the electric vehicle industry significantly aggravates the demand for lithium-ion batteries (LIBs), especially the ternary cathode materials, however, the majority of end-of-life (EOL) LIBs on the market are batteries utilized in customer electronics. Here, we utilized the mixed EOL LIBs from cell phones and laptops to manufacture the LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode material. A feasible, high efficiency (99.98% Co, 99.98% Ni, 99.99% Mn, and 99.99% Li), and ultra-fast leaching of EOL LIB cathodes was achieved. Thermodynamic calculations suggested that the coordination number, coordination species concentrations, and fractions have significant effects on the apparent activation energy and the equilibrium of the leaching reactions. The remanufactured NCM622 cathode material demonstrated a well-ordered layered hexagonal structure with a low Li+/Ni2+ mixing ratio, which facilitated reliable reversible capacity, low polarization, high rate capabilities (163.8 mA h g-1), and capacity retention ratio (94.3%).

Imaging Guided Endogenic H2 -Augmented Electrochemo-Sonodynamic Domino Co-therapy of Tumor in Vivo.

Precise and on-demand release of sufficient hydrogen (H2 ) to tumor sites remains a key challenge for emerging H2 -oncotherapy, and little is known about the physiological effects of "abundant" H2 on complex tumor microenvironments (TME). Here, a highly efficient and cost-effective imaging-guided/-assessed H2 -therapy of tumors based on a joint electrochemo-sonodynamic treatment (H2 -EC/SD co-therapy) with strong "domino effect" triggered by endogenous H2 generation at tumor sites is reported to speedily eliminate tumor tissue (≤80 mm3 ) within 1 day. Adequate H2 is controllably generated in tumor sites through mild electrochemistry in vivo due to acidic TME by using clinical acupuncture Fe needles as electrodes. Besides starvation damage due to gas blockage/destruction of vessels, nano-/micro-bubbles of H2 formed in situ can elevate the tumor's internal temperature and burst vessels to further destroy the tumor under ultrasound irradiation. Remarkably, vulnerable homeostasis of TME is disturbed as H2 also participates in the physiological activity of tumor cells, leading to tumor dysfunction. Last but not least, the body's inflammatory response to cancer is reduced after the treatment, which is beneficial for the body's immune system during post-treatment recovery. Based on all of these merits, the H2 -EC/SD co-therapy provides a potentially safe and viable therapeutic strategy for future clinical applications.

Global Excess Mortality during COVID-19 Pandemic: A Systematic Review and Meta-Analysis.

BACKGROUND: Currently, reported COVID-19 deaths are inadequate to assess the impact of the pandemic on global excess mortality. All-cause excess mortality is a WHO-recommended index for assessing the death burden of COVID-19. However, the global excess mortality assessed by this index remains unclear. We aimed to assess the global excess mortality during the COVID-19 pandemic. METHODS: We searched PubMed, EMBASE, and Web of Science for studies published in English between 1 January 2020, and 21 May 2022. Cross-sectional and cohort studies that reported data about excess mortality during the pandemic were included. Two researchers independently searched the published studies, extracted data, and assessed quality. The Mantel-Haenszel random-effects method was adopted to estimate pooled risk difference (RD) and their 95% confidence intervals (CIs). RESULTS: A total of 79 countries from twenty studies were included. During the COVID-19 pandemic, of 2,228,109,318 individuals, 17,974,051 all-cause deaths were reported, and 15,498,145 deaths were expected. The pooled global excess mortality was 104.84 (95% CI 85.56-124.13) per 100,000. South America had the highest pooled excess mortality [134.02 (95% CI: 68.24-199.80) per 100,000], while Oceania had the lowest [-32.15 (95% CI: -60.53--3.77) per 100,000]. Developing countries had higher excess mortality [135.80 (95% CI: 107.83-163.76) per 100,000] than developed countries [68.08 (95% CI: 42.61-93.55) per 100,000]. Lower middle-income countries [133.45 (95% CI: 75.10-191.81) per 100,000] and upper-middle-income countries [149.88 (110.35-189.38) per 100,000] had higher excess mortality than high-income countries [75.54 (95% CI: 53.44-97.64) per 100,000]. Males had higher excess mortality [130.10 (95% CI: 94.15-166.05) per 100,000] than females [102.16 (95% CI: 85.76-118.56) per 100,000]. The population aged ≥ 60 years had the highest excess mortality [781.74 (95% CI: 626.24-937.24) per 100,000]. CONCLUSIONS: The pooled global excess mortality was 104.84 deaths per 100,000, and the number of reported all-cause deaths was higher than expected deaths during the global COVID-19 pandemic. In South America, developing and middle-income countries, male populations, and individuals aged ≥ 60 years had a heavier excess mortality burden.

The global trends and regional differences in incidence of Zika virus infection and implications for Zika virus infection prevention.

BACKGROUND: Zika virus (ZIKV) infection has potential result in severe birth effects. An improved understanding of global trend and regional differences is needed. METHODS: Annual ZIKV infection episodes and incidence rates were collected from Global Burden of Disease Study 2019. Episodes changes and estimated annual percentage changes (EAPCs) of age-standardized incidence rate (ASR) were calculated. Top passenger airport-pairs were obtained from the International Air Transport Association to understand places susceptible to imported ZIKV cases. RESULTS: Globally, the ASR increased by an average of 72.85% (95%CI: 16.47% to 156.53%) per year from 2011 to 2015 and subsequently decreased from 20.25 per 100,000 in 2015 to 3.44 per 100,000 in 2019. Most of ZIKV infections clustered in Latin America. The proportion of episodes in Central and Tropical Latin America decreased in 2019 with sporadic episodes elsewhere. High Socio-Demographic Index (SDI) regions had more episodes in 2019 than in 2015. Additionally, 15-49 years group had the largest proportion of episodes, females had a higher number of episodes, and a higher incidence rate of 70 plus group was observed in males than females. Certain cities in Europe, North America and Latin America/Caribbean had a high population mobility in ZIKV outbreak areas considered a high risk of imported cases. CONCLUSIONS: ZIKV infection is still a public health threat in Latin America and Caribbean and high SDI regions suffered an increasing trend of ZIKV infection. Interventions such as development of surveillance networks and vector-control should be attached to ZIKV control in these key regions. Reproductive suggestions should be taken to reduce ZIKV-related birth defects for the people of reproductive age who are facing a higher threat of ZIKV infection, especially females. Moreover, surveillance of travellers is needed to reverse the uptrends of travel-related imported ZIKV infection. More studies focusing on ZIKV should be performed to make targeted and effective prevention strategies in the future.

Incubation Period of COVID-19 Caused by Unique SARS-CoV-2 Strains: A Systematic Review and Meta-analysis.

Importance: Several studies were conducted to estimate the average incubation period of COVID-19; however, the incubation period of COVID-19 caused by different SARS-CoV-2 variants is not well described. Objective: To systematically assess the incubation period of COVID-19 and the incubation periods of COVID-19 caused by different SARS-CoV-2 variants in published studies. Data Sources: PubMed, EMBASE, and ScienceDirect were searched between December 1, 2019, and February 10, 2022. Study Selection: Original studies of the incubation period of COVID-19, defined as the time from infection to the onset of signs and symptoms. Data Extraction and Synthesis: Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline, 3 reviewers independently extracted the data from the eligible studies in March 2022. The parameters, or sufficient information to facilitate calculation of those values, were derived from random-effects meta-analysis. Main Outcomes and Measures: The mean estimate of the incubation period and different SARS-CoV-2 strains. Results: A total of 142 studies with 8112 patients were included. The pooled incubation period was 6.57 days (95% CI, 6.26-6.88) and ranged from 1.80 to 18.87 days. The incubation period of COVID-19 caused by the Alpha, Beta, Delta, and Omicron variants were reported in 1 study (with 6374 patients), 1 study (10 patients), 6 studies (2368 patients) and 5 studies (829 patients), respectively. The mean incubation period of COVID-19 was 5.00 days (95% CI, 4.94-5.06 days) for cases caused by the Alpha variant, 4.50 days (95% CI, 1.83-7.17 days) for the Beta variant, 4.41 days (95% CI, 3.76-5.05 days) for the Delta variant, and 3.42 days (95% CI, 2.88-3.96 days) for the Omicron variant. The mean incubation was 7.43 days (95% CI, 5.75-9.11 days) among older patients (ie, aged over 60 years old), 8.82 days (95% CI, 8.19-9.45 days) among infected children (ages 18 years or younger), 6.99 days (95% CI, 6.07-7.92 days) among patients with nonsevere illness, and 6.69 days (95% CI, 4.53-8.85 days) among patients with severe illness. Conclusions and Relevance: The findings of this study suggest that SARS-CoV-2 has evolved and mutated continuously throughout the COVID-19 pandemic, producing variants with different enhanced transmission and virulence. Identifying the incubation period of different variants is a key factor in determining the isolation period.

Engineering Plasmonic Environments for 2D Materials and 2D-Based Photodetectors.

Two-dimensional layered materials are considered ideal platforms to study novel small-scale optoelectronic devices due to their unique electronic structures and fantastic physical properties. However, it is urgent to further improve the light-matter interaction in these materials because their light absorption efficiency is limited by the atomically thin thickness. One of the promising approaches is to engineer the plasmonic environment around 2D materials for modulating light-matter interaction in 2D materials. This method greatly benefits from the advances in the development of nanofabrication and out-plane van der Waals interaction of 2D materials. In this paper, we review a series of recent works on 2D materials integrated with plasmonic environments, including the plasmonic-enhanced photoluminescence quantum yield, strong coupling between plasmons and excitons, nonlinear optics in plasmonic nanocavities, manipulation of chiral optical signals in hybrid nanostructures, and the improvement of the performance of optoelectronic devices based on composite systems.

Impact of COVID-19 Prevention and Control on the Influenza Epidemic in China: A Time Series Study.

Background. COVID-19 prevention and control measures might affect influenza epidemic in China since the nonpharmaceutical interventions (NPIs) and behavioral changes contain transmission of both SARS-CoV-2 and influenza virus. We aimed to explore the impact of COVID-19 prevention and control measures on influenza using data from the National Influenza Surveillance Network.Methods. The percentage of influenza-like illness (ILI%) in southern and northern China from 2010 to 2022 was collected from the National Influenza Surveillance Network. Weekly ILI% observed value from 2010 to 2019 was used to calculate estimated annual percentage change (EAPC) of ILI% with 95% confidence intervals (CIs). Time series analysis was applied to estimate weekly ILI% predicted values in 2020/2021 and 2021/2022 season. Impact index was used to explore the impact of COVID-19 prevention and control on influenza during nonpharmaceutical intervention and vaccination stages.Results. China influenza activity was affected by the COVID-19 pandemic and different prevention and control measures during 2020-2022. In 2020/2021 season, weekly ILI% observed value in both southern and northern China was at a low epidemic level, and there was no obvious epidemic peak in winter and spring. In 2021/2022 season, weekly ILI% observed value in southern and northern China showed a small peak in summer and epidemic peak in winter and spring. The weekly ILI% observed value was generally lower than the predicted value in southern and northern China during 2020-2022. The median of impact index of weekly ILI% was 15.11% in north and 22.37% in south in 2020/2021 season and decreased significantly to 2.20% in north and 3.89% in south in 2021/2022 season.Conclusion. In summary, there was a significant decrease in reported ILI in China during the 2020-2022 COVID-19 pandemic, particularly in winter and spring. Reduction of influenza virus infection might relate to everyday Chinese public health COVID-19 interventions. The confirmation of this relationship depends on future studies.

Effects of sludge retention time, carbon and initial biomass concentrations on selection process: From activated sludge to polyhydroxyalkanoate accumulating cultures.

Four sequence batch reactors (SBRs) fed by fermented sugar cane wastewater were continuously operated under the aerobic dynamic feeding (ADF) mode with different configurations of sludge retention time (SRT), carbon and initial biomass concentrations to enrich polyhydroxyalkanoate (PHA) accumulating mixed microbial cultures (MMCs) from municipal activated sludge. The stability of SBRs was investigated besides the enrichment performance. The microbial community structures of the enriched MMCs were analyzed using terminal restriction fragment length polymorphism (T-RFLP). The optimum operating conditions for the enrichment process were: SRT of 5days, carbon concentration of 2.52g COD/L and initial biomass concentration of 3.65g/L. The best enrichment performance in terms of both operating stability and PHA storage ability of enriched cultures (with the maximum PHA content and PHA storage yield (YPHA/S) of 61.26% and 0.68mg COD/mg COD, respectively) was achieved under this condition. Effects of the SRT, carbon concentration and initial biomass concentration on the PHA accumulating MMCs selection process were discussed respectively. A new model including the segmentation of the enrichment process and the effects of SRT on each phase was proposed.

Efficient polyhydroxyalkanoate (PHA) accumulation by a new continuous feeding mode in three-stage mixed microbial culture (MMC) PHA production process.

A new continuous feeding mode was developed to optimize the polyhydroxyalkanoates (PHAs) accumulation step in the three-stage PHAs production process by mixed microbial cultures (MMCs) using mixed volatile fatty acids (VFAs) as substrate. The continuous feeding assays under low biomass loading rate (BLR) (in the range of 3.5-5.5Cmol VFA/Cmol X/d) can be directly fed with feedstock with pH from 5.0 to 10.0 without any pH regulation. The maximum intracellular PHA content of 70.4% and system PHA yield (YPHA/S(sys)) of 0.81Cmol PHA/Cmol VFA were achieved under the continuous feeding mode at BLR of 3.86Cmol VFA/Cmol X/d when directly fed with substrate at pH 5. These values were higher than those under the pulse wise feeding mode with the same substrate and active biomass concentration. The results indicated that a self-balanced pH state was formed in the continuous feeding system. Further studies on the reaction pH and kinetics of the MMCs in the continuous feeding reactor were conducted to understand the pH variation mechanism and accumulation process. The optimal BLR to get high PHA content and YPHA/S(sys) was 3.5-5.5Cmol VFA/Cmol X/d.

A new method for polyhydroxyalkanoate (PHA) accumulating bacteria selection under physical selective pressure.

An aerobic dynamic discharge (ADD) process involving physical selective pressure to favor the accumulation of polyhydroxyalkanoates (PHAs) accumulating bacteria in microbial mixed cultures (MMCs) is proposed and evaluated in this study. Sequencing batch reactor PHA production in the ADD mode was compared to the conventional aerobic dynamic feeding (ADF) mode. Results showed that the cultures selected under the ADD mode showed a better PHA producing potential than ADF mode cultures in terms of both maximum PHA content and selection time, explained by altered physical selective pressure. The maximum PHA content of 74.16 (± 0.03)% and PHA yield of 0.72 (± 0.07) C mol PHA/C mol Ac were achieved after 30 days of the ADD operation, which were much higher than those obtained under the same organic loading rate in the ADF operation. The ADD mode is a promising method for quick selection of a strong-PHA accumulating culture.

Safety evaluation of Lactobacillus paracasei subsp. paracasei LC-01, a probiotic bacterium.

The safety of Lactobacillus paracasei subsp. paracasei LC-01 was evaluated for its use as a potential probiotic. In our in vitro study, the antibiotic resistance and the ability to produce biogenic amine were determined. The results showed that the strain was sensitive to all tested antibiotics and did not produce biogenic amine except for tyramine. The oral toxicity of this strain was evaluated in Balb/C mice. One hundred mice were divided into 10 groups. Four groups were administered 0, 10(8), 10(9), or 10(10) CFU/mouse per day dissolved in saline solution respectively, for 28 days. Three groups were injected intraperitoneally with 10(9) CFU/mouse dissolved in saline solution, and were killed 2, 5, and 10 days after injection. The last 3 groups were injected with the vehicle as controls respectively. The results showed that oral administration of the strain had no adverse effects on mouse body weight and that there was no treatment-associated bacterial translocation. Intraperitoneal administration caused a significant translocation to liver, spleen and kidney. However, this translocation did not cause illness or death throughout the experiment. The results suggest that L. paracasei subsp. paracasei LC-01 is likely to be safe for human consumption.

[Influence of substrate concentration on PHA production using fermented sugar cane as substrate].

PHA was a kind of biodegradable polymer produced by mixed microorganisms. In recent years, 3-stage PHA synthesis process (including substrate hydrolysis, culture selection, and PHA synthesis) was commonly used for PHA production. In this kind of process, culture selection is the key stage, which directly affects the PHA production efficiency. In order to deal with sludge bulking occurred in the culture selection system, this paper analyzes the influence of substrate concentration on culture selection efficiency as well as operation stability. Under different influent substrate concentrations of 560 mg x L(-1), 1 120 mg x L(-1) and 1 680 mg x L(-1), we confirmed that influent substrate concentration (COD) of 1 120 mg x L(-1) is the most suitable parameter for the bacteria enriching process after a long period of time under short SRT. After 94 days of cultivation, we achieved 50% of PHA content, 0.7145 COD/COD of PHA conversion rate and 0.191 2 mg x (mg x h)(-1) of specific PHA storage rate at the end of batch tests with nutrient starvation. The study also confirmed that glycogen level in cells has a close relationship with its PHA synthesis ability, which shows its potential to predict the enrichment efficiency.