Direct Monitoring of Membrane Fatty Acid Changes and Effects on the Isoleucine/ Valine Pathways in an ndgR Deletion Mutant of Streptomyces coelicolor

NdgR, a global regulator in soil-dwelling and antibiotic-producing Streptomyces, is known to regulate branched-chain amino acid metabolism by binding to the upstream region of synthetic genes. However, its numerous and complex roles are not yet fully understood. To more fully reveal the function of NdgR, phospholipid fatty acid (PLFA) analysis with gas chromatography-mass spectrometry (GC-MS) was used to assess the effects of an ndgR deletion mutant of Streptomyces coelicolor. The deletion of ndgR was found to decrease the levels of isoleucine- and leucine-related fatty acids but increase those of valine-related fatty acids. Furthermore, the defects in leucine and isoleucine metabolism caused by the deletion impaired the growth of Streptomyces at low temperatures. Supplementation of leucine and isoleucine, however, could complement this defect under cold shock condition. NdgR was thus shown to be involved in the control of branched-chain amino acids and consequently affected the membrane fatty acid composition in Streptomyces. While isoleucine and valine could be synthesized by the same enzymes (IlvB/N, IlvC, IlvD, and IlvE), ndgR deletion did not affect them in the same way. This suggests that NdgR is involved in the upper isoleucine and valine pathways, or that its control over them differs in some respect.

Polyhydroxybutyrate production from crude glycerol using a highly robust bacterial strain Halomonas sp. YLGW01

Petrochemical-based plastics are hardly biodegradable and a major cause of environmental pollution, and polyhydroxybutyrate (PHB) is attracting attention as an alternative due to its similar properties. However, the cost of PHB production is high and is considered the greatest challenge for its industrialization. Here, crude glycerol was used as a carbon source for more efficient PHB production. Among the 18 strains investigated, Halomonas taeanenisis YLGW01 was selected for PHB production due to its salt tolerance and high glycerol consumption rate. Furthermore, this strain can produce poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3 HV)) with 17 % 3 HV mol fraction when a precursor is added. PHB production was maximized through medium optimization and activated carbon treatment of crude glycerol, resulting in 10.5 g/L of PHB with 60 % PHB content in fed-batch fermentation. Physical properties of the produced PHB were analyzed, i.e., weight average molecular weight (6.8 × 10⁵), number average molecular weight (4.4 × 10⁵), and the polydispersity index (1.53). In the universal testing machine analysis, the extracted intracellular PHB showed a decrease in Young's modulus, an increase in Elongation at break, greater flexibility than authentic film, and decreased brittleness. This study confirmed that YLGW01 is a promising strain for industrial PHB production using crude glycerol.

Enhanced production of bio-indigo in engineered Escherichia coli, reinforced by cyclopropane-fatty acid-acyl-phospholipid synthase from psychrophilic Pseudomonas sp. B14-6

Indigo dye is an organic compound with a distinctive blue color. Most of the indigo currently used in industry is produced via chemical synthesis, which generates a large amount of wastewater. Therefore, several studies have recently been conducted to find ways to produce indigo eco-friendly using microorganisms. Here, we produced indigo using recombinant Escherichia coli with both an indigo-producing plasmid and a cyclopropane fatty acid (CFA)-regulating plasmid. The CFA-regulating plasmid contains the cfa gene, and its expression increases the CFA composition of the phospholipid fatty acids of the cell membrane. Overexpression of cfa showed cytotoxicity resistance of indole, an intermediate product formed during the indigo production process. This had a positive effect on indigo production and cfa originated from Pseudomonas sp. B 14-6 was used. Optimal conditions for indigo production were determined by adjusting the expression strain, culture temperature, shaking speed, and isopropyl β-D-1-thiogalactopyranoside concentration. Treatment with Tween 80 at a particular concentration to increase the permeability of the cell membrane had a positive effect on indigo production. The strain with the CFA plasmid produced 4.1 mM of indigo after 24 h of culture and produced 1.5-fold higher indigo than the control strain without the CFA plasmid that produced 2.7 mM.

Unraveling Biohydrogen Production and Sugar Utilization Systems in the Electricigen Shewanella marisflavi BBL25

Identification of novel, electricity-producing bacteria has garnered remarkable interest because of the various applications of electricigens in microbial fuel cell and bioelectrochemical systems. Shewanella marisflavi BBL25, an electricity-generating microorganism, uses various carbon sources and shows broader sugar utilization than the better-known S. oneidensis MR-1. To determine the sugar-utilizing genes and electricity production and transfer system in S. marisflavi BBL25, we performed an in-depth analysis using whole-genome sequencing. We identified various genes associated with carbon source utilization and the electron transfer system, similar to those of S. oneidensis MR-1. In addition, we identified genes related to hydrogen production systems in S. marisflavi BBL25, which were different from those in S. oneidensis MR-1. When we cultured S. marisflavi BBL25 under anaerobic conditions, the strain produced 427.58 ± 5.85 μl of biohydrogen from pyruvate and 877.43 ± 28.53 μl from xylose. As S. oneidensis MR-1 could not utilize glucose well, we introduced the glk gene from S. marisflavi BBL25 into S. oneidensis MR-1, resulting in a 117.35% increase in growth and a 17.64% increase in glucose consumption. The results of S. marisflavi BBL25 genome sequencing aided in the understanding of sugar utilization, electron transfer systems, and hydrogen production systems in other Shewanella species.

Algal biochar mediated detoxification of plant biomass hydrolysate: Mechanism study and valorization into polyhydroxyalkanoates

In this study, fourteen types of biochar produced using seven biomasses at temperatures 300 °C and 600 °C were screened for phenolics (furfural and hydroxymethylfurfural (HMF)) removal. Eucheuma spinosum biochar (EB-BC 600) showed higher adsorption capacity to furfural (258.94 ± 3.2 mg/g) and HMF (222.81 ± 2.3 mg/g). Adsorption kinetics and isotherm experiments interpreted that EB-BC 600 biochar followed the pseudo-first-order kinetic and Langmuir isotherm model for both furfural and HMF adsorption. Different hydrolysates were detoxified using EB-BC 600 biochar and used as feedstock for engineered Escherichia coli. An increased polyhydroxyalkanoates (PHA) production with detoxified barley biomass hydrolysate (DBBH: 1.71 ± 0.07 g PHA/L), detoxified miscanthus biomass hydrolysate (DMBH: 0.87 ± 0.03 g PHA/L) and detoxified pine biomass hydrolysate (DPBH: 1.28 ± 0.03 g PHA/L) was recorded, which was 2.8, 6.4 and 3.4 folds high as compared to undetoxified hydrolysates. This study reports the mechanism involved in furfural and HMF removal using biochar and valorization of hydrolysate into PHA.

Two-Stage Bio-Hydrogen and Polyhydroxyalkanoate Production: Upcycling of Spent Coffee Grounds

Coffee waste is an abundant biomass that can be converted into high value chemical products, and is used in various renewable biological processes. In this study, oil was extracted from spent coffee grounds (SCGs) and used for polyhydroxyalkanoate (PHA) production through Pseudomonas resinovorans. The oil-extracted SCGs (OESCGs) were hydrolyzed and used for biohydrogen production through Clostridium butyricum DSM10702. The oil extraction yield through n-hexane was 14.4%, which accounted for 97% of the oil present in the SCGs. OESCG hydrolysate (OESCGH) had a sugar concentration of 32.26 g/L, which was 15.4% higher than that of the SCG hydrolysate (SCGH) (27.96 g/L). Hydrogen production using these substrates was 181.19 mL and 136.58 mL in OESCGH and SCGH media, respectively. The consumed sugar concentration was 6.77 g/L in OESCGH and 5.09 g/L in SCGH media. VFA production with OESCGH (3.58 g/L) increased by 40.9% compared with SCGH (2.54 g/L). In addition, in a fed-batch culture using the extracted oil, cell dry weight was 5.4 g/L, PHA was 1.6 g/L, and PHA contents were 29.5% at 24 h.

Algal biomass to biohydrogen: Pretreatment, influencing factors, and conversion strategies

Hydrogen has gained attention as an alternative source of energy because of its non-polluting nature as on combustion it produces only water. Biological methods are eco-friendly and have benefits in waste management and hydrogen production simultaneously. The use of algal biomass as feedstock in dark fermentation is advantageous because of its low lignin content, high growth rate, and carbon-fixation ability. The major bottlenecks in biohydrogen production are its low productivity and high production costs. To overcome these issues, many advances in the area of biomass pretreatment to increase sugar release, understanding of algal biomass composition, and development of fermentation strategies for the complete recovery of nutrients are ongoing. Recently, mixed substrate fermentation, multistep fermentation, and the use of nanocatalysts to improve hydrogen production have increased. This review article evaluates the current progress in algal biomass pretreatment, key factors, and possible solutions for increasing hydrogen production.

Finding of Novel Galactose Utilizing Halomonas sp. YK44 for Polyhydroxybutyrate (PHB) Production

Polyhydroxybutyrate (PHB) is a biodegradable bioplastic with potential applications as an alternative to petroleum-based plastics. However, efficient PHB production remains difficult. The main cost of PHB production is attributed to carbon sources; hence, finding inexpensive sources is important. Galactose is a possible substrate for polyhydroxyalkanoate production as it is abundant in marine environments. Marine bacteria that produce PHB from galactose could be an effective resource that can be used for efficient PHB production. In this study, to identify a galactose utilizing PHB producer, we examined 16 Halomonas strains. We demonstrated that Halomonas cerina (Halomonas sp. YK44) has the highest growth and PHB production using a culture media containing 2% galactose, final 4% NaCl, and 0.1% yeast extract. These culture conditions yielded 8.98 g/L PHB (78.1% PHB content (w/w)). When galactose-containing red algae (Eucheuma spinosum) hydrolysates were used as a carbon source, 5.2 g/L PHB was produced with 1.425% galactose after treatment with activated carbon. Since high salt conditions can be used to avoid sterilization, we examined whether Halomonas sp. YK44 could produce PHB in non-sterilized conditions. Culture media in these conditions yielded 72.41% PHB content. Thus, Halomonas sp. YK44 is robust against contamination, allowing for long-term culture and economical PHB production.

Mental Health of Healthcare Workers in Indonesia, Philippines, and Taiwan During COVID-19 Pandemic: a Cross-Sectional Survey

OBJECTIVE

This study aims to determine factors associated with hesitation and motivation to work among healthcare workers (HCWs) in Indonesia, Philippines, and Taiwan during the COVID-19 pandemic.

METHODS

HCWs aged ≥20 years working in five hospitals in Indonesia, Philippines, and Taiwan were invited to participate in a self-administered mental health survey between 30 January 2021 and 31 August 2021. The 33-item questionnaire measured HCWs' perceived stress, level of motivation and hesitation to work, attitude and confidence regarding work, attitude on the policies by the hospital and government, and discrimination against the occupation. Each item was rated in a 4-point Likert scale from 0 (never) to 3 (always). Sociodemographic and occupational factors were also considered in data analysis.

RESULTS

Of 1349 participants, 671 (49.7%) were from Indonesia, 365 (27.1%) from Philippines, and 313 (23.2%) from Taiwan. Overall, 20.8% of participants showed motivation to work and only 4.7% showed hesitation to work. Compared with HCWs in their 20s, HCWs in their 30s, 40s, and 50s had significantly lower hesitation to work (adjusted odds ratio [AOR] = 0.42, 0.33, and 0.11, respectively; p = 0.01, 0.02, and 0.03, respectively). Similarly, compared with HCWs in their 20s, HCWs in their 30, 40s, 50s, 60s, and 70s had significantly higher motivation to work (AOR = 1.71, 2.98, 5.92, 5.40, and 7.15, respectively; p = 0.01, <0.001, <0.001, <0.001, and 0.02, respectively). Clinical staff had lower motivation to work than non-clinical staff (AOR = 0.60, p = 0.01). Those who worked in high-risk areas had lower hesitation to work than those who worked in low-risk areas (AOR = 0.51, p = 0.03). Overall, higher hesitation to work was associated with 'wanting to leave job/study' (AOR = 4.54, p = 0.03) and 'feeling isolated' (AOR = 4.84, p = 0.01), whereas lower hesitation to work was associated with 'being confident about the future of medical practice' (AOR = 0.33, p = 0.02) and 'burden of child care including lack of nursery' (AOR = 0.30, p = 0.04). Higher motivation to work was associated with 'feeling of being protected by hospital' (AOR = 2.23, p = 0.001), 'confident in my country's pandemic prevention policy' (AOR = 2.19, p = 0.001), 'feeling of elevated mood' (AOR = 4.14, p = 0.004), and 'being confident about the future of medical practice' (AOR = 2.56, p < 0.001), whereas lower motivation to work was associated with 'exhausted mentally' (AOR = 0.35, p = 0.03).

CONCLUSION

Various stress-related factors contribute to hesitation and motivation to work among HCWs in Indonesia, Philippines, and Taiwan during the COVID-19 pandemic. Proactive and practical strategies should be implemented to protect HCWs from the negative behavioural and emotional effects of the COVID-19 pandemic.

Coproduction of exopolysaccharide and polyhydroxyalkanoates from Sphingobium yanoikuyae BBL01 using biochar pretreated plant biomass hydrolysate

Sphingobium yanoikuyae BBL01 can produce exopolysaccharides (EPS) and polyhydroxyalkanoates (PHAs). The effect of side products (furfural, hydroxymethylfurfural (HMF), vanillin, and acetate) produced during pretreatment of biomass was evaluated on S. yanoikuyae BBL01. It was observed that a certain concentration range (0.01-0.03 %) of these compounds can improve growth, EPS production, and polyhydroxybutyrate (PHB) accumulation. The addition of HMF increases glucose and xylose utilization while other side products have a negative effect. The C/N of 5 favors EPS production (3.24 ± 0.05 g/L), while a higher C/N ratio of 30 promotes PHB accumulation (38.7 ± 0.08 % w/w), when commercial sugar is used as a carbon source. Pine biomass-derived biochar was able to remove 40 ± 2.1 % of total phenolic. Various biomass hydrolysates were evaluated and the use of detoxified pine biomass hydrolysate (DPH) as a carbon source resulted in the higher coproduction of EPS (2.83 ± 0.03 g/L) and PHB (40.8 ± 2.4 % w/w).

Acceleration of Polybutylene Succinate Biodegradation by Terribacillus sp. JY49 Isolated from a Marine Environment

Polybutylene succinate (PBS) is a bioplastic substitute for synthetic plastics that are made from petroleum-based products such as polyethylene and polypropylene. However, the biodegradation rate of PBS is still low and similar to that of polylactic acid (PLA). Moreover, our knowledge about degrader species is limited to a few fungi and mixed consortia. Here, to identify a bacterial degrader to accelerate PBS degradation, we screened and isolated Terribacillus sp. JY49, which showed significant degradability. In order to optimize solid and liquid culture conditions, the effect of factors such as temperature, additional carbon sources, and salt concentrations on degradation was confirmed. We observed a degradation yield of 22.3% after 7 days when adding 1% of glucose. Additionally, NaCl was added to liquid media, and degradation yield was decreased but PBS films were broken into pieces. Comparing the degree of PBS degradation during 10 days, the degradation yield was 31.4% after 10 days at 30 °C. Alteration of physical properties of films was analyzed by using scanning electron microscopy (SEM), gel permeation chromatography (GPC), and Fourier transform infrared (FT-IR). In addition, Terribacillus sp. JY49 showed clear zones on poly(butylene adipate-co-terephthalate) (PBAT), polycaprolactone (PCL), and copolymers such as P(3HB-co-3HV) and P(3HV-co-4HB), exhibiting a broad spectrum of degradation activities on bioplastics. However, there was no significant difference in absorbance when esterase activity was examined for different types of bioplastics. Overall, Terribacillus sp. JY49 is a potential bacterial strain that can degrade PBS and other bioplastics, and this is the first report of Terribacillus sp. as a bioplastic degrader.

Controlling catabolite repression for isobutanol production using glucose and xylose by overexpressing the xylose regulator

Using lignocellulosic biomass is immensely beneficial for the economical production of biochemicals. However, utilizing mixed sugars from lignocellulosic biomass is challenging because of bacterial preference for specific sugar such as glucose. Although previous studies have attempted to overcome this challenge, no studies have been reported on isobutanol production from mixed sugars in the Escherichia coli strain. To overcome catabolite repression of xylose and produce isobutanol using mixed sugars, we applied the combination of three strategies: (1) deletion of the gene for the glucose-specific transporter of the phosphotransferase system (ptsG); (2) overexpression of glucose kinase (glk) and glucose facilitator protein (glf); and (3) overexpression of the xylose regulator (xylR). xylR gene overexpression resulted in 100% of glucose and 82.5% of xylose consumption in the glucose-xylose mixture (1:1). Moreover, isobutanol production increased by 192% in the 1:1 medium, equivalent to the amount of isobutanol produced using only glucose. These results indicate the effectiveness of xylR overexpression in isobutanol production. Our findings demonstrated various strategies to overcome catabolite repression for a specific product, isobutanol. The present study suggests that the selected strategy in E. coli could overcome the major challenge using lignocellulosic biomass to produce isobutanol.

Enhanced tolerance of Cupriavidus necator NCIMB 11599 to lignocellulosic derived inhibitors by inserting NAD salvage pathway genes

Polyhydroxybutyrate (PHB) is a bio-based, biodegradable and biocompatible plastic that has the potential to replace petroleum-based plastics. Lignocellulosic biomass is a promising feedstock for industrial fermentation to produce bioproducts such as polyhydroxybutyrate (PHB). However, the pretreatment processes of lignocellulosic biomass lead to the generation of toxic byproducts, such as furfural, 5-HMF, vanillin, and acetate, which affect microbial growth and productivity. In this study, to reduce furfural toxicity during PHB production from lignocellulosic hydrolysates, we genetically engineered Cupriavidus necator NCIMB 11599, by inserting the nicotine amide salvage pathway genes pncB and nadE to increase the NAD(P)H pool. We found that the expression of pncB was the most effective in improving tolerance to inhibitors, cell growth, PHB production and sugar consumption rate. In addition, the engineered strain harboring pncB showed higher PHB production using lignocellulosic hydrolysates than the wild-type strain. Therefore, the application of NAD salvage pathway genes improves the tolerance of Cupriavidus necator to lignocellulosic-derived inhibitors and should be used to optimize PHB production.

Investigation of metabolic crosstalk between host and pathogenic Clostridioides difficile via multiomics approaches

Clostridioides difficile is a gram-positive anaerobic bacterium that causes antibiotic-associated infections in the gut. C. difficile infection develops in the intestine of a host with an imbalance of the intestinal microbiota and, in severe cases, can lead to toxic megacolon, intestinal perforation, and even death. Despite its severity and importance, however, the lack of a model to understand host-pathogen interactions and the lack of research results on host cell effects and response mechanisms under C. difficile infection remain limited. Here, we developed an in vitro anaerobic-aerobic C. difficile infection model that enables direct interaction between human gut epithelial cells and C. difficile through the Mimetic Intestinal Host–Microbe Interaction Coculture System. Additionally, an integrative multiomics approach was applied to investigate the biological changes and response mechanisms of host cells caused by C. difficile in the early stage of infection. The C. difficile infection model was validated through the induction of disaggregation of the actin filaments and disruption of the intestinal epithelial barrier as the toxin-mediated phenotypes following infection progression. In addition, an upregulation of stress-induced chaperones and an increase in the ubiquitin proteasomal pathway were identified in response to protein stress that occurred in the early stage of infection, and downregulation of proteins contained in the electron transfer chain and ATP synthase was observed. It has been demonstrated that host cell energy metabolism is inhibited through the glycolysis of Caco-2 cells and the reduction of metabolites belonging to the TCA cycle. Taken together, our C. difficile infection model suggests a new biological response pathway in the host cell induced by C. difficile during the early stage of infection at the molecular level under anaerobic-aerobic conditions. Therefore, this study has the potential to be applied to the development of future therapeutics through basic metabolic studies of C. difficile infection.

Lignocellulosic hydrolysate based biorefinery for marine exopolysaccharide production and application of the produced biopolymer in environmental clean-up

The present study deals with the utilization of lignocellulosic hydrolysate-based carbon source for exopolysaccharide (EPS) production using newly reported marine Echinicola sediminis BBL-M-12. This bacterium produced 7.56 g L^-1 and 5.32 g L^-1 of EPS on supplementing 30 g L^-1 glucose and 10 g L^-1 xylose as the sole carbon source, respectively. Whereas on feeding Miscanthus hydrolysate (MCH) with glucose content adjusting to 20 g L^-1, E. sediminis BBL-M-12 produced 6.18 g L^-1 of EPS. The inhibitors study showed bacterium could tolerate higher concentrations of fermentation inhibitors include furfural (0.05%), 5-hydroxymethylfurfural (0.1%), vanillin (0.1%) and acetate (0.5%). Moreover, the EPS composition was greatly altered with the type and concentration of carbon source supplied, although β-D-Glucopyranose, β-D-Galactopyranose, and β-D-Xylopyranose were the dominant monomers detected. Interestingly, E. sediminis BBL-M-12 EPS revealed excellent environmental applications like clay flocculation, oil emulsification, and removal of humic acid, textile dye, and heavy metal from the aqueous phase.

Advances in algal biomass pretreatment and its valorisation into biochemical and bioenergy by the microbial processes

Urbanization and pollution are the major issues of the current time own to the exhaustive consumption of fossil fuels which have a detrimental effect on the nation's economies and air quality due to greenhouse gas (GHG) emissions and shortage of energy reserves. Algae, an autotrophic organism provides a green substitute for energy as well as commercial products. Algal extracts become an efficient source for bioactive compounds having anti-microbial, anti-oxidative, anti-inflammatory, and anti-cancerous potential. Besides the conventional approach, residual biomass from any algal-based process might act as a renewable substrate for fermentation. Likewise, lignocellulosic biomass, algal biomass can also be processed for sugar recovery by different pre-treatment strategies like acid and alkali hydrolysis, microwave, ionic liquid, and ammonia fiber explosion, etc. Residual algal biomass hydrolysate can be used as a feedstock to produce bioenergy (biohydrogen, biogas, methane) and biochemicals (organic acids, polyhydroxyalkanoates) via microbial fermentation.

Constructing multi-enzymatic cascade reactions for selective production of 6-bromoindirubin from tryptophan in Escherichia coli

6-Bromoindirubin (6BrIR), found in Murex sea snails, is a precursor of indirubin-derivatives anticancer drugs. However, its synthesis remains limited due to uncharacterized biosynthetic pathways and difficulties in site-specific bromination and oxidation at indole ring. Here, we present an efficient 6BrIR production strategy in E. coli by using four enzymes, i.e., tryptophan 6-halogenase fused with flavin reductase Fre (Fre-L3-SttH), tryptophanase (TnaA), toluene 4-monooxygenase (PmT4MO) and flavin-containing monooxygenase (MaFMO). Although most indole oxygenases preferentially oxygenate the electronically active C3 position of indole, PmT4MO was newly characterized to perform C2 oxygenation of 6-bromoindole with 45 % yield to produce 6-bromo-2-oxindole. In addition, 6BrIR was selectively generated without indigo and indirubin byproducts by controlling the reducing power of cysteine and oxygen supply during the MaFMO reaction. These approaches led to 34.1 mg/L 6BrIR productions, making it possible to produce the critical precursor of the anticancer drugs only from natural ingredients such as tryptophan, NaBr and oxygen. This article is protected by copyright. All rights reserved.

[Clinical characteristics and prognostic factors of 1 166 patients with uveal melanoma]

Objective: To analyze the clinical characteristics and survival of Chinese uveal melanoma (UM) patients. Methods: It was a retrospective case series study. Clinical data and demography characteristics of 1 166 UM patients who were diagnosed in Beijing Tongren Hospital from January 2004 to January 2020 were collected. The disease was followed up after informed consent was obtained. Kaplan-Meier plots were used to visualize survival outcomes, and the different risk groups were compared using the Log-rank test. The multivariate Cox proportional hazards model was used to select independent prognostic risk factors. Results: A total of 1 166 individuals (598 men, 568 women) were included in this study. The average age was (47.6±12.2) years. Median follow-up time was 38 months. Treatment included episcleral brachytherapy in 881 (75.6%) patients, local tumor resection in 38 (3.2%) patients, laser therapy in 115 (9.9%) patients and primary enucleation in 119 (10.2%) patients. In 120 patients out of the 881 patients with primary brachytherapy, enucleation was performed due to an increasing tumor size or uncontrolled neovascular glaucoma. The Kaplan-Meier survival analysis showed the 5-and 10-year metastasis rates were 18.5% and 26.8%, and the melanoma-related mortality rates were 13.6% and 22.2%, respectively. The Log-rank test showed that patient age (χ²=5.01) and gender (χ²=7.19), as well as tumor grade (χ²=49.11), shape (χ²=34.73), location (χ²=18.60), pathological type (χ²=8.07), presence of subretinal fluid (χ²=15.71) and ciliary body involvement (χ²=19.72) were factors influencing patient prognoses (all P<0.05). In the multivariate Cox analysis, the T2, T3, T4 tumors (compared with the T1 tumor, HR=4.41, 6.82, 10.49), subretinal fluid (HR=1.98), ciliary body involvement (HR=1.79), being male (HR=1.53) and advanced age (greater than 53 years old) (HR=1.83) were independent risk factors for poor prognoses (all P<0.05). Conclusions: UM occurs at a significantly earlier age and non-pigmented tumors represent smaller proportion in Chinese patients. Higher T-stage, presence of subretinal fluid, ciliary body involvement, advanced age, and being male are independent risk factors for poor outcomes.

4-Chloro-2-Isopropyl-5-Methylphenol Exhibits Antimicrobial and Adjuvant Activity against Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) causes severe infections and poses a global healthcare challenge. The utilization of novel molecules which confer synergistical effects to existing MRSA-directed antibiotics is one of the well-accepted strategies in lieu of de novo development of new antibiotics. Thymol is a key component of the essential oil of plants in the Thymus and Origanum genera. Despite the absence of antimicrobial potency, thymol is known to inhibit MRSA biofilm formation. However, the anti-MRSA activity of thymol analogs is not well characterized. Here, we assessed the antimicrobial activity of several thymol derivatives and found that 4-chloro-2-isopropyl-5-methylphenol (chlorothymol) has antimicrobial activity against MRSA and in addition it also prevents biofilm formation. Chlorothymol inhibited staphyloxanthin production, slowed MRSA motility, and altered bacterial cell density and size. This compound also showed a synergistic antimicrobial activity with oxacillin against highly resistant S. aureus clinical isolates and biofilms associated with these isolates. Our results demonstrate that chlorinated thymol derivatives should be considered as a new lead compound in anti-MRSA therapeutics.

Bioconversion of Mixed Alkanes to Polyhydroxyalkanoate by Pseudomonas resinovornas: Upcycling of Pyrolysis Oil from Waste-Plastic

Polyhydroxyalkanoate (PHA) is a biodegradable plastic that can be used to replace petroleum-based plastic. In addition, as a medium-chain-length PHA (mcl-PHA), it can be used to provide elastomeric properties in specific applications. Because of these characteristics, recently, there has been much research on mcl-PHA production using inexpensive biomass materials as substrates. In this study, mcl-PHA producers were screened using alkanes (n-octane, n-decane, and n-dodecane) as sources of carbon. The amount of PHA produced by Pseudomonas resinovorans using sole n-octane, n-decane, or n-dodecane was 0.48 g/L, 0.27 g/L, or 0.07 g/L, respectively, while that produced using mixed alkane was 0.74 g/L. As a larger amount of PHA was produced using mixed alkane compared with sole alkane, a statistical mixture analysis was used to determine the optimal ratio of alkanes in the mixture. The optimal ratio predicted by the analysis was a medium with 9.15% n-octane, 6.44% n-decane, and 4.29% n-dodecane. In addition, through several concentration-specific experiments, the optimum concentrations of nitrogen and phosphorus for cell growth and maximum PHA production were determined as 0.05% and 1.0%, respectively. Finally, under the determined optimal conditions, 2.1 g/L of mcl-PHA and 60% PHA content were obtained using P. resinovorans in a 7 L fermenter.

Progress in microalgal mediated bioremediation systems for the removal of antibiotics and pharmaceuticals from wastewater

Worldwide demand for antibiotics and pharmaceutical products is continuously increasing for the control of disease and improvement of human health. Poor management and partial metabolism of these compounds result in the pollution of aquatic systems, leading to hazardous effects on flora, fauna, and ecosystems. In the past decade, the importance of microalgae in micropollutant removal has been widely reported. Microalgal systems are advantageous as their cultivation does not require additional nutrients: they can recover resources from wastewater and degrade antibiotics and pharmaceutical pollutants simultaneously. Bioadsorption, degradation, and accumulation are the main mechanisms involved in pollutant removal by microalgae. Integration of microalgae-mediated pollutant removal with other technologies, such as biodiesel, biochemical, and bioelectricity production, can make this technology more economical and efficient. This article summarizes the current scenario of antibiotic and pharmaceutical removal from wastewater using microalgae-mediated technologies.