Production of Bacterial Cellulose Using Low-cost Media

Bacterial cellulose (BC) is a polymer of glucose monomers, which has unique properties including high crystallinity and high strength. It has the potential to be used in biomedical applications such as making artificial blood vessels, wound dressings, and in the paper making industry. Unlike cellulose from plant sources, it is not contaminated with non-cellulose compounds, making it a candidate for medical use. The aim of this thesis was to optimize BC production using the Gram negative bacterium Gluconacetobacter xylinus DSM 46604, including identifying cheaper ingredients for the culture media. Initial trials were done on solid media and in shake flasks. Trials were then scaled and done in 3-L and 5-L conventional bioreactors. Three different processing strategies were used in the bioreactors: batch, fed-batch and continuous. The morphology of the BC depended on the growth conditions. Thin sheets were formed in stationary cultures and pellicles were formed in agitated cultures. The scanning electron microscope micrographs showed that BC produced under static culture tends to be more densely packed than when produced in agitated shake flasks. Exploratory trials on agar slants and in agitated shake flasks using glucose, sucrose, and lactose showed that G. xylinus DSM 46604 grew well on glucose and produced BC. However, there was minimal growth on the other two carbohydrates. Further trials with initial glucose concentrations between 40 and 100 g/L were done in shake flasks. Glucose concentration did not affect the BC morphology. The maximum BC concentration of 1.13 g/L was produced using 50 g/L glucose. The BC concentration using 100 g/L glucose was only 0.96 g/L. Shake flask studies with 2 to 9 g/L yeast extract (YE) as a nitrogen source in the media showed the maximum BC concentration of 5.2 g/L was obtained using 5 g/L YE with 50 g/L of glucose. Increasing the YE to 7 or 9 g/L produced only 4.82 and 4.06 g BC/L respectively. The effect of two cheaper nitrogen sources, fish hydrolysate and fish powder prepared from waste fish, were investigated. The highest BC concentration of 0.24 g/L was obtained using 20 g/L fish hydrolysate rather than 5 g/L YE. The BC yield of 0.04 g BC /g carbon substrate used were obtained using 5 g/L YE, 20 g/L fish hydrolysate, or 15 or 20 g/L fish powder. The effectiveness of four combinations of banana peel (as a cheaper carbon source) and glucose were investigated in shake flasks trials. The highest BC concentration of 0.43 g/L was obtained using 10 g/L banana peel extract with 40 g/L glucose. This was similar to the BC concentration produced with 50 g/L glucose (control). Trials using the same combination of banana peel and glucose in a 3-L bioreactor produced 1 g/L BC compared with 2.2 g/L for 50 g/L glucose (control). Shake flask fermentations using 10 to 50 g/L glycerol as the carbon source showed that the highest BC concentration of 1.43 g/L was produced with an initial glycerol of 20 g/L. Trials done in a 3-L bioreactor produced 2.87 g/L of BC, representing a yield of 0.15 g/g carbon substrate used. The effect of aeration and agitation on BC production was studied in 3- and 5-L bioreactors. The optimal agitation was 200 rpm at constant air flow rate of 0.3 volume air per volume culture broth per minute (vvm). This produced 4.0 g/L BC and a yield of 0.06 g/g glucose. The optimal aeration rate at 150 rpm was 1.0 vvm and produced 4.4 g/L BC. Various fermentation strategies were then investigated. The control was batch fermentation on 50 g/L glucose in a 3- or 5-L fermenter. All runs were done at 30OC, 200 rpm and 1 vvm aeration. The BC yield when G. xylinus DSM 46604 was grown on 50 g/L glucose using a fill-and-draw fed-batch strategy was 0.05 g/g glucose or glycerol used, which was similar to the control. The BC yield increased to 0.11 g/g when using a pulse-feed fed-batch strategy but the BC yield in continuous fed-batch was only 0.03 g/g. It increased under continuous fermentation conditions and the highest yield (0.13 g/g) was achieved at a dilution rate of 0.1 h⁻¹. If dilution rate was increased further, yields began to decrease. Trials were done by replacing 50 g/L glucose with 20 g/L glycerol. Again, BC yields were higher under continuous conditions than batch fermentation. The BC yield on 20 g/L using a fill-and-draw fed-batch strategy was 0.2 g/g BC compared with 0.15 g/g for the control. This increased to 0.39 g/g for a pulse-feed fed-batch strategy. The BC yield for continuous fed-batch at a dilution rate of 0.1 h⁻¹ was 0.3 g/g. The highest BC yield under continuous conditions was 0.33 g/g when dilution rate was 0.1 h⁻¹. These studies showed that cheaper ingredients such as fish powder or hydrolysate and banana peel extract could partially replace conventional nitrogen and carbon sources such as YE and glucose without affecting BC yield. The BC production was enhanced using fed-batch and continuous processing strategies. Higher BC yields than reported by much of the literature could be obtaining ujsing a combination of low-cost media ingredients and the best reactor conditions

Positive fluid balance predicts mortality in intensive care unit patients

Background Positive fluid balance is known to be a factor to cause poor outcome in critically ill patients especially in patient with acute kidney injury. The goal of this study is to assess the outcome of positive fluid balance in general patients admitted to intensive care unit, Hospital Sultanah Nur Zahirah. Objectives The main objective is to determine the association of positive fluid balance in causing mortality of the critically patients who were managed in ICU. Methodology This is a retrospective cohort study. The patients who fulfilled the inclusion criteria and were admitted to ICU between April 1st, 2012 and December 31st, 2013 were included in this study. Data were abstracted from the medical record. Univariate analysis and multivariate analysis were carried out to determine the association and the risk ratio of PFB in predicting the death in ICU patients. ROC curve was plotted to assess the optimal cut-off point. Results: A total of 200 patients were recruited for this study from which 40 patients were died and 160 patients were alive during discharge from ICU. More than 90% of the patients were Malays. The mean (SD) age group was 53.4 (18.1) years old. The main reasons for ICU admission were respiratory failure (46%) and septic shock with respiratory failure 51%). Univariate analysis and multivariate analysis showed that those with positive fluid balance of > 1L per day had 4-fold risk of dying as compared to those with average fluid balance of <1L per day (RR=4.0, 95% CI 2.20, 7.36, P <0.01). The ROC curve showed the cut off point for average fluid balance that risk to mortality was 987 ml per day. Conclusion: The average positive fluid balance of >1L per day during ICU stay is a risk factor for mortality among the critically ill patients managed in ICU

Pembangunan augmanted reality (AR) bagi matapelajaran sains (sistem suria)

Kajian ini bertujuan untuk membangunkan aplikasi augmented reality bag itopik sistem suria untuk pembelajaran murid-murid Tahun Empat. Aplikasi ini berperanan sebagai penggayaan ilmu yang menggunakan elemen-elemen multimedia dalam pengajaran dan pembelajaran (PdP). Pembangunan aplikasi augmented reality ini adalah berasaskan model Hannafin dan Peck yang melibatkan tiga fasa utama iaitu fasa analisis keperluan, fasa reka bentuk serta fasa pembangunan dan implementasi. Kemajuan teknologi boleh digunakan dalam pendidikan sebagai cara mengajar dalam institusi pendidikan formal dan bukan formal, dalam pendidikan. Kaedah pembelajaran boleh dipersembahkan menggunakan alat bantuan pembelajaran atau sering dikenali sebagai media pembelajaran. Augmented reality dilihat sebagai media pengajaran masa depan yang inovatif, menarik dan efektif

Nutritive Value of Barley Fodder Grown in a Hydroponics System

A series of experiments were conducted to evaluate barley fodder (BF) as a feed for ruminants. Barley seeds were grown in a specially designed and controlled environment cabin at 15 - 18°C. The first experiment was conducted to germinate barley seeds from day 0 (dO) to day 10 (dIO, n=ll) and samples were collected daily for chemical composition analysis. In the second experiment, the rumen simulation technique (RUSITEC) was used to measure the in vitro dry matter (DM) and crude protein (CP) digestibility and the volatile fatty acids (VF A) produced by BF at different times. The nylon bag technique was also used to measure the DM degradability of BF in the rumen of cattle at 2, 4, 8, 12, 24 and 48 hours. The third experiment on the intake and digestibility of eight-day old BF was measured by an in vivo technique, using four bucks. The fourth experiment involved the measurement of rumen fluid parameters (pH, ammonia and VFA) in three rumen fistulated bucks that were fed on eight-day old BF ad libitum. The CP, organic matter (OM), ether extract (EE), neutral detergent fibre (NDF), acid detergent fibre (ADF) and crude fibre (CF) contents of BF from d1 to d10 increased, but the DM content decreased with the age of BF. DM content at d7 and d8 were 16 and 18% while CP content were 12 and 13% respectively. The amount of calcium (Ca), phosphorus (P) and Nitrate (N03) did not change significantly throughout sprouting time. The in vivo, in vitro and in sacco DM degradability studies showed that 80 to 100% DM loss for BF harvested on d7 to dW. DM intake was lower in the third experiment although digestion coefficient (DC) of BF was very high (98%). This condition was probably due to the abnormal growth of BF during the experimental period. Rumen fluid pH was 5.9-6.0 and ammonia-N (NH3-N) content was 7.0 to 8.8 mg/mL. Total fatty acids production was 70 to 1 00 mmoVL between two and eight hour of collection. The acetic:propionic:butyric ratios were 58:36:1.3, 68:25:2, 61:35:1.2, 64:33:0.7 and 65:32:1 at 0, 2, 4, 6 and 8 hours, respectively. Overall results showed that VFA and ammonia-nitrogen (NH3-N) were produced at a minimum level when BF was given ad libitum although the digestibility was higher in both in sacco and in vitro studies. BF should be given at different levels in order to get optimum pH, VFA and NH3-N production

Fish powder as a low-cost component in media for producing bacterial cellulose

Some bacteria can produce extracellular bacterial cellulose (BC). This polysaccharide is chemically identical to cellulose produced by plants but has no associated lignin and hemicelluloses. The unique mechanical properties, chemical stability and purity allow BC to be exploited for a range of biomedical applications. However, medium costs limit commercial BC production. The suitability of using fish powder as a low-cost media component for producing BC by submerged culture of Gluconacetobacter xylinus in shake flasks was investigated. Fish powder was made by drying and grinding Koi carp (Cyprinus carpio), a pest fish in New Zealand waterways. Fermentations were done at 30oC in a growth medium containing 50 g/L glucose, the required minerals, and either 5 g/L yeast extract or 15 g/L fish powder, The BC yield on both yeast extract and fish powder was 0.04 g/g glucose, demonstrating fish powder was a suitable low cost ingredient for supplying nitrogen and amino acids in the media

The effect of virgin coconut oil loaded solid lipid particles (VCO-SLPs) on skin hydration and skin elasticity

Virgin Coconut Oil is usually extracted from well matured and fresh coconut through specialized processes without damaging its natural nutrition. In this work, formulation, characterization and efficacy of VCO-SLPs have been studied. VCO-SLPs were prepared using ultrasonification of molten stearic acid and virgin coconut oil in an aqueous solution and particles with the size of 0.608 μm have been obtained. 20% concentration of VCO-SLPs of 0.608 μm particle size was added into the base lotion. Sensory study and skin evaluation study was conducted to compare the difference between lotion containing VCO-SLPs and lotion without VCO-SLPs. Moisturizing lotion incorporated with VCO-SLPs was found to increase skin hydration and skin elasticity by 24.8% and 2.60% respectively from day 0 to day 28. This shows that solid lipid particles has the potential to be utilized as a carrier for improved dermal delivery of VCO

The effects of on-call duties on cognitive functions in anaesthesia residents husm

INTRODUCTION Cognitive functions play a vital role in safe anaesthetic practice and there are various factors that affect the cognitive functions. OBJECTIVES The aim of this study is to determine the effects on cognitive functions in anesthesia residents doing on-call duty in HUSM and to compare between demographic factors and on-call features with cognitive functions. METHODOLOGY This study includes all the anesthesia residents in the Department of Anaesthesiology, HUSM after written informed consent was obtained. The data was collected from 1st January until 28th February 2010. Four cognitive tests were used in this study which were Mini Mental State Examination (MMSE), Stroop Color Word Test (SCWT), Concentration Test (CT) and Reaction Time Test (RTT). Other associated factors affected by on-call such as Stanford Sleepiness Scale (SSS), Busy Score (BS) and psychological Stress Score (PSY) were also recorded

Customer-Orientation Behaviour: Antecedents And Its Impact On Sales Performance Of Life Insurance Agents

Tingkahlaku berorientasikan · pelanggan yang merujuk kepada sejauhmana jurujual mengamalkan konsep pemasaran dengan menolong pelanggan membuat keputusan pembelian yang memenuhi keperluan dan kep~n mereka telah dianggap sebagai ciri penting untuk menjadi jurujual yang berjaya. Customer-orientation behaviour, which refers to the degree to which salespeople practice the marketing concept by trying to help their customers make purchase decisions that will satisfy customers' needs and satisfaction has been acknowledged as an important characteristics of high performers