Comparison of various microbial inocula for the efficient anaerobic digestion of Laminaria hyperborea

Background: The hydrolysis of seaweed polysaccharides is the rate limiting step in anaerobic digestion (AD) of seaweeds. Seven different microbial inocula and a mixture of these (inoculum 8) were therefore compared in triplicate, each grown over four weeks in static culture for the ability to degrade Laminaria hyperborea seaweed and produce methane through AD. Results: All the inocula could degrade L. hyperborea and produce methane to some extent. However, an inoculum of slurry from a human sewage anaerobic digester, one of rumen contents from seaweed-eating North Ronaldsay sheep and inoculum 8 used most seaweed volatile solids (VS) (means ranged between 59 and 68% used), suggesting that these each had efficient seaweed polysaccharide digesting bacteria. The human sewage inoculum, an inoculum of anaerobic marine mud mixed with rotting seaweed and inoculum 8 all developed to give higher volumes of methane (means between 41 and 62.5 ml g-1 of seaweed VS by week four) ,compared to other inocula (means between 3.5 and 27.5 ml g-1 VS). Inoculum 8 also gave the highest acetate production (6.5 mmol g-1 VS) in a single-stage fermenter AD system and produced most methane (8.4 mL mmol acetate-1) in phase II of a two-stage AD system. Conclusions: Overall inoculum 8 was found to be the most efficient inoculum for AD of seaweed. The study therefore showed that selection and inclusion of efficient polysaccharide hydrolysing bacteria and methanogenic archaea in an inoculum offer increased methane productivity in AD of L. hyperborea. This inoculum will now being tested in larger scale (10L) continuously stirred reactors optimised for feed rate and retention time to determine maximum methane production under single-stage and two-stage AD systems.Marie Curie Senior Researcher Fellowship (SEAWEED AD

To Tube, or Not to Tube: Comparing Ventilation Techniques in Microlaryngeal Surgery

OBJECTIVES/HYPOTHESIS: The objective of this study was to compare ventilation techniques utilized in microlaryngeal surgery. STUDY DESIGN: Retrospective cohort study. METHODS: Two-hundred surgeries performed from May 1, 2018 to March 1, 2020 and stratified as intubated, intermittently intubated (AAIV) or apneic. Patient demographics, comorbidities, anesthetic agents, intraoperative parameters/events, and complications were studied and compared across the three groups using inferential analyses. RESULTS: Median body mass index in the AAIV group was significantly higher (33 vs. 29; P = .0117). Median oxygen nadirs were lower in AAIV cases (81% vs. 91-92%) while CO peak measurements were lower (33 mmHg vs. 48 mmHg) in the fully apneic cohort which were significantly shorter cases (P \u3c .0001). CO peak measurements were comparable between AAIV and intubated cohorts (median 48.5 mmHg vs. 48.0 mmHg). Median apnea times were significantly prolonged by 2-5.5 minutes using nasal cannula and THRIVE/Optiflow in fully apneic cases when compared to no supplementary oxygenation (P = .0013). Systolic blood pressures following insertion of laryngoscope were higher (159.5 vs. 145 mmHg) and postoperative diastolic pressures were lower (68.5 vs. 76.5 mmHg) in fully apneic cases than intubated cases. No differences existed between frequencies of complications. CONCLUSIONS: This study compares intubated, intermittently apneic, and fully apneic surgeries. No statistically significant differences were noted in comorbid conditions. While intraoperative hemodynamic fluctuations were more pronounced in the fully apneic cohort, and oxygenation distributions were lower in the AAIV cohort, no significant differences existed between events and complications. Apneic techniques are as safe and effective as traditional intubation. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:2773-2781, 2021