A green pathway for lignin valorization: Enzymatic lignin depolymerization in biocompatible ionic liquids and deep eutectic solvents.

Lignin depolymerization, which enables the breakdown of a complex and heterogeneous aromatic polymer into relatively uniform derivatives, serves as a critical process in valorization of lignin. Enzymatic lignin depolymerization has become a promising biological strategy to overcome the heterogeneity of lignin, due to its mild reaction conditions and high specificity. However, the low solubility of lignin compounds in aqueous environments prevents efficient lignin depolymerization by lignin-degrading enzymes. The employment of biocompatible ionic liquids (ILs) and deep eutectic solvents (DESs) in lignin fractionation has created a promising pathway to enzymatically depolymerize lignin within these green solvents to increase lignin solubility. In this review, recent research progress on enzymatic lignin depolymerization, particularly in a consolidated process involving ILs/DESs is summarized. In addition, the interactions between lignin-degrading enzymes and solvent systems are explored, and potential protein engineering methodology to improve the performance of lignin-degrading enzymes is discussed. Consolidation of enzymatic lignin depolymerization and biocompatible ILs/DESs paves a sustainable, efficient, and synergistic way to convert lignin into value-added products.

A lack of an association between COVID-19 vaccination and corneal graft rejection: results of a large multi-country population based study.

PURPOSE: The aim of the study was to present the rates of corneal transplant rejection from 2018 to 2022 at both Moorfields Eye Hospital UK, and Ospedali Privati Forli (OPF) "Villa Igea", Italy and evaluate the purported association between COVID-19 vaccination and rejection. METHODS: We performed a retrospective review of rejection cases presenting to the two units. Monthly rates were correlated against regional vaccination programme rates. At OPF, conditional Poisson regression model was employed to estimate the incidence risk ratio (IRR) of graft rejection following COVID-19 vaccination risk period compared with the control period. RESULTS: Between January 2018 and March 2022, there were 471 (Moorfields), 95 (OPF) episodes of rejection. From the start of vaccination programme in the UK in late January 2021, the median number of graft rejections per month at Moorfields was 6 (range: 5-9), which was not significantly different to post-lockdown, pre-vaccination programme (March 2020-January 2021), p = 0.367. At OPF, the median rates of rejection before and after initiation of the vaccination programme were not significantly different (p = 0.124). No significant increase in incidence rate of rejection in the risk period following COVID-19 vaccination was found (IRR = 0.53, p = 0.71). CONCLUSION: No notable increase in rates of transplant rejection was noted in year 2021 when COVID-19 vaccination was broadly implemented. The apparent temporal relationship between COVID-19 vaccination and corneal graft rejection highlighted in several case reports may not represent a causative association.

A review on strategies to reduce ionic liquid pretreatment costs for biofuel production.

Worldwide demand for renewable energy has promoted the considerable exploration of biofuel production from lignocellulosic biomass. Ionic liquid pretreatment is of great interest to render biomass amenable for biofuel production, however, its unaffordable cost stimulates significant attention to the feasibility of commercialization. This review aims to compile the latest advances with respect to reducing production costs for ionic liquids-based biorefineries. Protic ionic liquids offer relatively low synthesis costs, but excessive antisolvent washing of the pretreated biomass is often inevitable. Recovering ionic liquids requires several separation and purification steps, and the reuse of ionic liquids could significantly lose functionality due to the degradation. It is promising to screen ionic liquids-tolerant enzymes and strains for one-pot saccharification and fermentation without solid-liquid separation, however, there is still a need for subsequent recovery of ionic liquids. Additionally, technoeconomic analysis and life cycle assessment are highly recommended to evaluate the economic and environmental impacts.

'Posture-Less' DMEK: Is Posturing After Descemet Membrane Endothelial Keratoplasty Actually Necessary?

PURPOSE: To evaluate the clinical results of Descemet membrane endothelial keratoplasty (DMEK) without any intraoperative or postoperative posturing. DESIGN: Retrospective, noncomparative, and interventional case series. METHODS: One hundred thirty-four (134) consecutive eyes of 101 patients requiring DMEK for any cause of endothelial failure were included. Descemet membrane endothelial keratoplasty was performed with an intraoperative inferior PI. After unscrolling and centration of the graft, the anterior chamber was near completely filled with 20% SF6. After filling the eye with gas there was no intraoperative tamponade time, and patients did not posture postoperatively. Main outcome measures were: graft detachment rate, rebubbling rate, primary and secondary failure rates, rejection rate, intraoperative and postoperative complications, and visual acuity 3 and 12 months after surgery. RESULTS: Five of 134 (3.7%) developed graft detachment greater than one-third of the graft area, and 19 of 134 (14.2%) developed graft detachment less than one-third of the graft area. A rebubble procedure was performed in 19 of 134 (14.2%); of those, the average number of rebubbling procedures performed was 1.13 (range, 1-2). Primary failure occurred in 6 of 134 (4.5%).Twelve-month graft survival occurred in 122 of 134 eyes (91.0%), with secondary failure within the first 12 months accounting for failure of 6 of 134 (4.5%). Nine of 134 (6.7%) cases had a recorded episode of endothelial rejection. The average time for rejection episode was 9.5 months (range, 1-20 months) after surgery. CONCLUSIONS: A total of 134 'posture-less' DMEKs did not suffer very high rates of graft detachment, rebubbling, or other postoperative complications, even with immediate erect posturing after surgery.

Exploring lignin depolymerization by a bi-enzyme system containing aryl alcohol oxidase and lignin peroxidase in aqueous biocompatible ionic liquids.

Enzymatic depolymerization of lignin to produce low molecular weight products requires mild reaction conditions and exhibits higher selectivity compared to thermochemical lignin depolymerization. However, it remains challenging to depolymerize lignin enzymatically, partially due to the low solubility of lignin in aqueous phase. This study aimed to develop a novel approach to combine aqueous lignin extraction with enzymatic lignin depolymerization in biocompatible ionic liquids. A bi-enzyme system containing aryl alcohol oxidase (AAO) and lignin peroxidase (LiP) was developed to depolymerize lignin. Temperature and pH profiles for LiP and AAO were determined. Biocompatibilities of LiP and AAO in different deep eutectic solvents and ionic liquids were investigated. Aqueous cholinium glycinate was found to be an efficient and suitable solvent to solubilize lignin and serve as a biocompatible medium for enzymes to work. LiP and AAO together reduced lignin molecular weight in both solid and liquid phase after enzymatic lignin depolymerization.

One step forward, two steps back: Transcriptional advancements and fermentation phenomena in Actinobacillus succinogenes 130Z.

Within the field of bioproduction, non-model organisms offer promise as bio-platform candidates. Non-model organisms can possess natural abilities to consume complex feedstocks, produce industrially useful chemicals, and withstand extreme environments that can be ideal for product extraction. However, non-model organisms also come with unique challenges due to lack of characterization. As a consequence, developing synthetic biology tools, predicting growth behavior, and building computational models can be difficult. There have been many advancements that have improved work with non-model organisms to address broad limitations, however each organism can come with unique surprises. Here we share our work in the non-model bacterium Actinobacillus succinognes 130Z, which includes both advancements in synthetic biology toolkit development and pitfalls in unpredictable fermentation behaviors. To develop a synthetic biology "tool kit" for A. succinogenes, information gleaned from a growth study and antibiotic screening was used to characterize 22 promoters which demonstrated a 260-fold range of fluorescence protein expression. The strongest of the promoters was incorporated into an inducible system for tunable gene control in A. succinogenes using the promoter for the lac operon as a template. This system flaunted a 481-fold range of expression and no significant basal expression. These findings were accompanied by unexpected changes in fermentation products characterized by a loss of succinic acid and increase in lactic acid after approximately 10 months in the lab. During evaluation of the fermentation shifts, new tests of the synthetic biology tools in a succinic acid producing strain revealed a significant loss in their functionality. Contamination and mutation were ruled out as causes and further testing is needed to elucidate the driving factors. The significance of this work is to share a successful tool development strategy that could be employed in other non-model species, report on an unfortunate phenomenon that needs addressed for further development of A. succinogenes, and provide a cautionary tale for those undertaking non-model research. In sharing our findings, we seek to provide tools and necessary information for further development of A. succinogenes as a platform for bioproduction of succinic acid and to illustrate the importance of diligent and long-term observation when working with non-model bacteria.

Fed-batch production of Thermothelomyces thermophilus lignin peroxidase using a recombinant Aspergillus nidulans strain in stirred-tank bioreactor.

Enzymatic lignin depolymerization is considered a favorable approach to utilize lignin due to the higher selectivity and less energy requirement when compared to thermochemical lignin valorization. Lignin peroxidase (LiP) is one of the key enzymes involved in lignin degradation and possesses high redox potential to oxidize non-phenolic structures and phenolic compounds in lignin. However, the production of LiP is mainly from white-rot fungi at small scales. It is critical to discover new LiP from other microorganisms and produce LiP at large scales. This study aims to produce a novel LiP originally from Thermothelomyces thermophiles using a recombinant Aspergillus nidulans strain. The LiP production medium was optimized, and different fed-batch strategies for LiP production were investigated to improve LiP activity, yield, and productivity. Results demonstrated that LiP production was enhanced by using multi-pulse fed-batch fermentation. A maximum LiP activity of 1,645 mU/L with a protein concentration of 0.26 g/L was achieved.

Femtosecond laser-assisted cataract surgery compared with phacoemulsification: the FACT non-inferiority RCT.

BACKGROUND: Cataract surgery is one of the most common operations. Femtosecond laser-assisted cataract surgery (FLACS) is a technique that automates a number of operative steps. OBJECTIVES: To compare FLACS with phacoemulsification cataract surgery (PCS). DESIGN: Multicentre, outcome-masked, randomised controlled non-inferiority trial. SETTING: Three collaborating NHS hospitals. PARTICIPANTS: A total of 785 patients with age-related cataract in one or both eyes were randomised between May 2015 and September 2017. INTERVENTION: FLACS (n = 392 participants) or PCS (n = 393 participants). MAIN OUTCOME MEASURES: The primary outcome was uncorrected distance visual acuity in the study eye after 3 months, expressed as the logarithm of the minimum angle of resolution (logMAR): 0.00 logMAR (or 6/6 if expressed in Snellen) is normal (good visual acuity). Secondary outcomes included corrected distance visual acuity, refractive outcomes (within 0.5 dioptre and 1.0 dioptre of target), safety and patient-reported outcome measures at 3 and 12 months, and resource use. All trial follow-ups were performed by optometrists who were masked to the trial intervention. RESULTS: A total of 353 (90%) participants allocated to the FLACS arm and 317 (81%) participants allocated to the PCS arm attended follow-up at 3 months. The mean uncorrected distance visual acuity was similar in both treatment arms [0.13 logMAR, standard deviation 0.23 logMAR, for FLACS, vs. 0.14 logMAR, standard deviation 0.27 logMAR, for PCS, with a difference of -0.01 logMAR (95% confidence interval -0.05 to 0.03 logMAR; p = 0.63)]. The mean corrected distance visual acuity values were again similar in both treatment arms (-0.01 logMAR, standard deviation 0.19 logMAR FLACS vs. 0.01 logMAR, standard deviation 0.21 logMAR PCS; p = 0.34). There were two posterior capsule tears in the PCS arm. There were no significant differences between the treatment arms for any secondary outcome at 3 months. At 12 months, the mean uncorrected distance visual acuity was 0.14 logMAR (standard deviation 0.22 logMAR) for FLACS and 0.17 logMAR (standard deviation 0.25 logMAR) for PCS, with a difference between the treatment arms of -0.03 logMAR (95% confidence interval -0.06 to 0.01 logMAR; p = 0.17). The mean corrected distance visual acuity was 0.003 logMAR (standard deviation 0.18 logMAR) for FLACS and 0.03 logMAR (standard deviation 0.23 logMAR) for PCS, with a difference of -0.03 logMAR (95% confidence interval -0.06 to 0.01 logMAR; p = 0.11). There were no significant differences between the arms for any other outcomes, with the exception of the mean binocular corrected distance visual acuity with a difference of -0.02 logMAR (95% confidence interval -0.05 to 0.00 logMAR) (p = 0.036), which favoured FLACS. There were no significant differences between the arms for any health, social care or societal costs. For the economic evaluation, the mean cost difference was £167.62 per patient higher for FLACS (95% of iterations between -£14.12 and £341.67) than for PCS. The mean QALY difference (FLACS minus PCS) was 0.001 (95% of iterations between -0.011 and 0.015), which equates to an incremental cost-effectiveness ratio (cost difference divided by QALY difference) of £167,620. LIMITATIONS: Although the measurement of outcomes was carried out by optometrists who were masked to the treatment arm, the participants were not masked. CONCLUSIONS: The evidence suggests that FLACS is not inferior to PCS in terms of vision after 3 months' follow-up, and there were no significant differences in patient-reported health and safety outcomes after 12 months' follow-up. In addition, the statistically significant difference in binocular corrected distance visual acuity was not clinically significant. FLACS is not cost-effective. FUTURE WORK: To explore the possible differences in vision in patients without ocular co-pathology. TRIAL REGISTRATION: Current Controlled Trials ISRCTN77602616. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 6. See the NIHR Journals Library website for further project information. Moorfields Eye Charity (grant references GR000233 and GR000449 for the endothelial cell counter and femtosecond laser used).

Cataract is a condition in which the natural lens inside the eye becomes cloudy, leading to loss of vision. In cataract surgery, the cloudy lens is replaced by a clear, artificial one. The standard surgical method (phacoemulsification) is carried out manually by the surgeon using ultrasound. Part of the procedure can now be automated using a computer-controlled laser. This is called femtosecond laser-assisted cataract surgery (FLACS). The potential advantages of FLACS include greater precision reproducibility, but this new technique is more expensive than the standard surgery. We performed a randomised controlled trial comparing the two techniques. We assessed vision, surgical complications, patient-related quality of life and cost-effectiveness at 3 and 12 months. We found that the outcomes were almost identical for eyesight, quality of life and complications. Overall, the evidence suggests that the new technique is not worth the additional costs.

Fed-batch polyhydroxybutyrate production by Paraburkholderia sacchari from a ternary mixture of glucose, xylose and arabinose.

Polyhydroxybutyrate (PHB) is a biodegradable bioplastic that is comparable with many petroleum-based plastics in terms of mechanical properties and is highly biocompatible. Lignocellulosic biomass conversion into PHB can increase profit and add sustainability. Glucose, xylose and arabinose are the main monomer sugars derived from upstream lignocellulosic biomass processing. The sugar mixture ratios may vary greatly depending on the pretreatment and enzymatic hydrolysis conditions. Paraburkholderia sacchari DSM 17165 is a bacterium strain that can convert all three sugars into PHB. In this study, fed-batch mode was applied to produce PHB on three sugar mixtures (glucose:xylose:arabinose = 4:2:1, 2:2:1, 1:2:1). The highest PHB concentration produced was 67 g/L for 4:2:1 mixture at 41 h corresponding to an accumulation of 77% of cell dry weight as PHB. Corresponding sugar conversion efficiency and productivity were 0.33 g PHB/g sugar consumed and 1.6 g/L/h, respectively. The results provide references for process control to maximize PHB production from real sugar streams derived from corn fibre.

Femtosecond laser-assisted cataract surgery compared with phacoemulsification cataract surgery: randomized noninferiority trial with 1-year outcomes.

PURPOSE: To report the 1-year outcomes of a randomized trial comparing femtosecond laser-assisted cataract surgery (FLACS) and phacoemulsification cataract surgery (PCS). SETTING: Moorfields Eye Hospital, New Cross Hospital, and Sussex Eye Hospital, United Kingdom. DESIGN: Multicenter, randomized controlled noninferiority trial. METHODS: Patients undergoing cataract surgery were randomized to FLACS or PCS. Postoperative assessments were masked. Outcomes included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), complications, corneal endothelial cell count, and patient-reported outcomes measures. RESULTS: The study enrolled 785 participants. A total of 311 of 392 (79%) participants were allocated to FLACS and 292 of 393 (74%) participants were allocated to PCS attended follow-up at 1 year. Mean UDVA was 0.14 (SD = 0.22) for FLACS and 0.17 (0.25) for PCS with difference of -0.03 logarithm of the minimum angle of resolution (logMAR) (95%, -0.06 to 0.01, P = .17). Mean CDVA was 0.003 (0.18) for FLACS and 0.03 (0.23) for PCS with difference of -0.03 logMAR (95% CI, -0.06 to 0.01, P = .11); 75% of both FLACS (230/307) and PCS (218/290) cases were within ±0.5 diopters (D) refractive target, and 292 (95%) of 307 eyes of FLACS and 279 (96%) of 290 eyes of PCS groups were within ±1.0 D. There were no significant differences between arms for all other outcomes with the exception of binocular CDVA mean difference -0.02 (-0.05 to 0.002) logMAR (P = .036) favoring FLACS. Mean cost difference was £167.62 per patient greater for FLACS (95% iterations between -£14.12 and £341.67). CONCLUSIONS: PCS is not inferior to FLACS regarding vision, patient-reported health, and safety outcomes after 1-year follow-up. A difference was found for binocular CDVA, which, although statistically significant, was not clinically important. FLACS was not cost-effective.

Process optimization and scale-up production of fungal aryl alcohol oxidase from genetically modified Aspergillus nidulans in stirred-tank bioreactor.

Microbial production of aryl alcohol oxidase (AAO) has attracted increasing attention due to the central role of AAO in enzymatic lignin depolymerization. However, large-scale production of AAO has not been reached because of the low yield and inefficient fermentation process. This study aims to optimize the process parameters and scale-up production of AAO using Aspergillus nidulans in a stirred-tank bioreactor. Effects of pH and dissolved oxygen on AAO production at bioreactor scale were particularly investigated. Results revealed that pH control significantly affected protein production and increasing dissolved oxygen level stimulated AAO production. The greatest AAO activity (1906 U/L) and protein concentration (1.19 g/L) were achieved in 48 h at 60% dissolved oxygen with pH controlled at 6.0. The yield and productivity (in 48 h) were 31.2 U/g maltose and 39.7 U/L/h, respectively. In addition, crude AAO was concentrated and partially purified by ultrafiltration and verified by protein identification.

Femtosecond Laser-Assisted Cataract Surgery Versus Phacoemulsification Cataract Surgery (FACT): A Randomized Noninferiority Trial.

PURPOSE: To report the 3-month results of a randomized trial (Femtosecond Laser-Assisted Cataract Trial [FACT]) comparing femtosecond laser-assisted cataract surgery (FLACS) with standard phacoemulsification cataract surgery (PCS). DESIGN: Multicenter, randomized controlled trial funded by the UK National Institute of Health Research (HTA 13/04/46/). PARTICIPANTS: Seven hundred eighty-five patients with age-related cataract. METHODS: This trial took place in 3 hospitals in the UK National Health Service (NHS). Randomization (1:1) was stratified by site, surgeon, and 1 or both eyes eligible using a secure web-based system. Postoperative assessments were masked to the allocated intervention. The primary outcome was unaided distance visual acuity (UDVA) in the study eye at 3 months. Secondary outcomes included corrected distance visual acuity, complications, and patient-reported outcomes measures. The noninferiority margin was 0.1 logarithm of the minimum angle of resolution (logMAR). ISRCTN.com registry, number ISRCTN77602616. MAIN OUTCOME MEASURES: We enrolled 785 participants between May 2015 and September 2017 and randomly assigned 392 to FLACS and 393 to PCS. At 3 months postoperatively, mean UDVA difference between treatment arms was -0.01 logMAR (-0.05 to 0.03), and mean corrected distance visual acuity difference was -0.01 logMAR (95% confidence interval [CI], -0.05 to 0.02). Seventy-one percent of both FLACS and PCS cases were within ±0.5 diopters (D) of the refractive target, and 93% of FLACS and 92% of PCS cases were within ±1.0 D. There were 2 posterior capsule tears in the PCS arm and none in the FLACS arm. There were no significant differences between arms for any secondary outcome. CONCLUSIONS: Femtosecond laser-assisted cataract surgery is not inferior to conventional PCS surgery 3 months after surgery. Both methods are as good in terms of vision, patient-reported health, and safety outcomes at 3 months. Longer-term outcomes of the clinical effectiveness and cost-effectiveness are awaited.

Optimization of process parameters and fermentation strategy for xylanase production in a stirred tank reactor using a mutant Aspergillus nidulans strain.

The present work studied the optimization of aeration rate, agitation rate and oxygen transfer and the use of various batch fermentation strategies for xylanase production from a recombinant Aspergillus nidulans strain in a 3 L stirred tank reactor. Maximum xylanase production of 1250 U/mL with productivity of 313 U/mL/day was obtained under an aeration rate of 2 vvm and an agitation rate of 400 rpm using batch fermentation. The optimum volumetric oxygen transfer coefficient (kLa) for efficient xylanase production was found to be 38.6 h-1. Fed batch mode and repeated batch fermentation was also performed with kLa was 38.6 h-1. Xylanase enzyme productivity increased to 327 with fed batch fermentation and 373 U/mL/day with repeated batch fermentation. Also, maximum xylanase activity increased to 1410 U/mL with fed batch fermentation and 1572 U/mL with repeated batch fermentation.

Recent advances in polyhydroxyalkanoate production: Feedstocks, strains and process developments.

Polyhydroxyalkanoates (PHAs) have been actively studied in academia and industry for their properties comparable to petroleum-derived plastics and high biocompatibility. However, the major limitation for commercialization is their high cost. Feedstock costs, especially carbon costs, account for the majority of the final cost. Finding cheap feedstocks for PHA production and associated process development are critical for a cost-effective PHA production. In this study, waste materials from different sources, particularly lignocellulosic biomass, were proposed as suitable feedstocks for PHA production. Strains involved in the conversion of these feedstocks into PHA were reviewed. Newly isolated strains were emphasized. Related process development, including the factors that affect PHA production, fermentation modes and downstream processing, was elaborated upon.

Development of a cost-effective medium for submerged production of fungal aryl alcohol oxidase using a genetically modified Aspergillus nidulans strain.

Aryl alcohol oxidase (AAO), an extracellular H2O2-providing enzyme, plays a central role in lignin depolymerization. Cost-effective production of AAO has not been achieved, due to the low yield of enzyme-producing microorganisms and the high cost of fermentation media. This study aims to develop a cost-effective medium for high-yield production of AAO in submerged culture using a recombinant Aspergillus nidulans strain. Results demonstrate that corn steep liquor (CSL) was a rich but inexpensive nitrogen source for AAO production, and CSL can provide enough trace metals and vitamins (i.e. pyridoxine) for A. nidulans. A 2-level Plackett-Burman design was utilized to determine the main affecting factors in AAO production. The medium was further optimized by a 3-level Box-Behnken design to obtain the optimum medium component concentrations (61.0 g/L maltose, 26.4 g/L CSL, and 13.8 g/L NaNO3). The greatest AAO activity achieved was 1021 U/L with a protein concentration of 0.75 g/L.

Heterologous expression and functional characterization of a GH10 endoxylanase from Aspergillus fumigatus var. niveus with potential biotechnological application.

Xylanases decrease the xylan content in pretreated biomass releasing it from hemicellulose, thus improving the accessibility of cellulose for cellulases. In this work, an endo-ß-1,4-xylanase from Aspergillus fumigatus var. niveus (AFUMN-GH10) was successfully expressed. The structural analysis and biochemical characterization showed this AFUMN-GH10 does not contain a carbohydrate-binding module. The enzyme retained its activity in a pH range from 4.5 to 7.0, with an optimal temperature at 60 °C. AFUMN-GH10 showed the highest activity in beechwood xylan. The mode of action of AFUMN-GH10 was investigated by hydrolysis of APTS-labeled xylohexaose, which resulted in xylotriose and xylobiose as the main products. AFUMN-GH10 released 27% of residual xylan from hydrothermally-pretreated corn stover and 14% of residual xylan from hydrothermally-pretreated sugarcane bagasse. The results showed that environmentally friendly pretreatment followed by enzymatic hydrolysis with AFUMN-GH10 in low concentration is a suitable method to remove part of residual and recalcitrant hemicellulose from biomass.

Optimization of polyhydroxybutyrate production by experimental design of combined ternary mixture (glucose, xylose and arabinose) and process variables (sugar concentration, molar C:N ratio).

Conversion of lignocellulosic feedstocks to polyhydroxybutyrate (PHB) could make lignocellulosic biorefineries more profitable and sustainable. Glucose, xylose and arabinose are the main sugars derived from pretreatment and hydrolysis of herbaceous feedstocks. Burkholderia sacchari DSM 17165 is a bacterium that can convert these sugars into PHB. However, the effects of sugar ratio, sugar concentration, and molar C:N ratio on PHB production have not been studied. In this study, a seven-run mixture design for sugar ratio combined with a 32 full factorial design for process variables was performed to optimize PHB production. A polynomial model was built based on experimental data, and optimum conditions for different sugar streams were derived and validated. The highest PHB production (3.81 g/L) was achieved with arabinose at a concentration of 25.54 g/L and molar C:N ratio of 74.35. Results provide references for manipulation of sugar mixture and process control to maximize PHB production.

Anterior Segment Optical Coherence Tomographic Angiography Assessment of Acute Chemical Injury.

PURPOSE: To compare routine clinical examination with optical coherence tomography angiography (OCTA) for the assessment of limbal conjunctival ischemia following a chemical burn. SETTING: Validity analysis. METHODS: We assessed 10 participants (15 eyes) with an acute chemical injury. Clinical photographs were used to determine the extent of any limbal conjunctival epithelial defect and ischemia. These were compared with the extent of limbal ischemia identified on OCTA images of the ocular surface. Quantitative and longitudinal analysis using the OCTA software were also performed. Correlations with visual outcome were sought using clinical and OCTA-derived variables. RESULTS: The extent of clinically determined limbal ischemia was less than that identified with OCTA (2.3±3.6 clock hours vs 5.1±4.2 clock hours, P = .003), which in turn was less than the size of limbal conjunctival epithelial defect (7.3±5.1 clock hours, P = .03). Longitudinal OCTA analysis showed that mean vessel area increased by 0.2%±0.1% during the study, corresponding to a rate of vascular recovery of 0.9 mm2/d. Significant correlations were found between visual outcome at 3 months and limbal conjunctival fluorescein staining (r = 0.67, P = .006), and limbal conjunctival ischemia on OCTA (r = 0.76, P = .001). CONCLUSIONS: OCTA can objectively identify and monitor the recovery of limbal ischemia following an acute ocular chemical injury. OCTA confirms that limbal ischemia is usually more extensive than is suggested by clinical examination, and the former is highly correlated with visual outcome. OCTA therefore is a useful tool in the management of ocular chemical injury.

Fungal infection after endothelial keratoplasty: association with hypothermic corneal storage.

PURPOSE: To compare the incidence of fungal infection after endothelial keratoplasty (EK) when donor tissue had been stored in hypothermic medium or organ culture. METHODS: We describe the clinical features of 10 cases of fungal infection (keratitis or endophthalmitis) following EK identified at three European centres. Case definition was the culture of fungus or a positive PCR from the host cornea or anterior chamber after EK. A survey of the incidence of infection after EK was conducted by the European Eye Bank Association. The main outcome measure was the number of cases in which donor tissue had been stored in hypothermic medium compared with organ culture. RESULTS: The 10 cases occurred between 2014 and 2017. All donor corneas had been stored in hypothermic medium sourced from three US eye banks. Three pairs of mate corneas caused infections in six recipients. Candida spp were identified from nine cases, with one isolate of Purpureocillium lilacinum. Data on 16 862 corneas supplied for EK were available from 16 European eye banks for the 5-year period from 2012. There were 17 reported cases of infection, of which 15 (88%) were fungal infections and 14 (82%) were Candida spp. Fungal infection was reported from 3 of 14 476 (0.02%) corneas supplied in organ culture compared with 12 of 2386 (0.50%) corneas supplied in hypothermic medium (p<0.0001). The incidence of infection after hypothermic storage was similar for material sourced from Europe (0.52%) or the USA (0.61%). CONCLUSIONS: Infection after EK is strongly associated with Candida spp. The possible explanations for the higher incidence of infection when tissue is stored in hypothermic medium are discussed.