Large quantities of oyster mushroom (Pleurotus sajor caju. )spent medium (MSM) were disposed of as agricultural waste to the environment and thereby constituting environmental pollution. Therefore the study was conducted to examine the feasibility of using MSM as glucose source in comparison to RSD and GM under different NaOH pretreatment techniques and at the same enzymatic saccharification condition. The composition analysis proved that decreases in lignocellulosic contents occurred after cultivation of The amount of lignin, hemicelluloses, and cellulose in MSM showed lower values than those in RSD and GM which were 22.40, 27.93, and 27.97% respectively. The surface morphology of MSM appeared to be rough and broken and traces of hyphen on the fibre surface were observed as a result from the mushroom cultivation process. RSD and FM had an even and smooth flat surface, indicating a rigid and highly ordered surface structure. The highest glucose yield were obtained from MSM under all three NaOH pretreatment techniques (autoclaving at 121°C, heating in water bath, soaking at room temperature), that were 31.07, 30.13, and 21.97, g/ dry substrate respectively. The amount of glucose obtained from RSD and GM under the same treatments were comparable.
Bacillus subtilis is a type of gastrointestinal bacteria that build up a healthy gut microbiota. The bacterial species has been well documented to involve in maintaining a healthy gut homeostasis in which disruption in it’s microbial composition or “dysbiosis” has recently been linked to obesity. Probiotic in vivo restoration of dysbiosed microbiota have been proved successful in obese CD-1 mice model. However, prebiotic study using Gum Arabic (GA) assessing to optimise an in vitro lumen system specifically targeting to enhance the growth of B. subtilis are still lacking since this bacteria are depleted in obese individuals. Thus, this study aimed to establish the optimal growth conditions in simulated in vitro lumen system and to the best of our knowledge, this is the first in vitro study attempted to optimize the growth of B. subtilis in medium supplemented with prebiotic GA. Growth screening analysis suggested an optimal dosage of 1.0% and 0.5% glucose and GA, respectively. The highest growth rate was recorded at 0.7995 hours−1 with doubling time of 52.02 minutes with extended period of stationary phase. The optimal GA concentration and fermentation conditions were determined at 0.67%, pH 7.4 and temperature of 37°C. The validated suggested model indicates that the supplementation of GA into an optimal fermentation systems is promising to enhance the growth of gut microflora Bacillus subtilis, for restoration of a dysbiosed gut microbiota in vitro.
In this study, dried seaweed (Gracilaria sp.), a red algae was used as feedstock for the production of bioethanol due to its high carbohydrate content (76.67 %). Dried seaweed is hydrolysed into reducing sugar by using dilute acid hydrolysis pre-treatment at optimized conditions (0.1 M sulphuric acid (H2SO4), 121 °C, 30 minutes) and able to obtain 18.438 g/L of reducing sugar. This hydrolysate is converted into bioethanol by Saccharomyces cerevisiae via fermentation. Two significant factors, namely, fermentation temperature and medium pH were screened by performing One-Factor-At-A-Time (OFAT) analysis. The first factor manipulated was the fermentation temperature (40-50 °C at pH 4.5), followed by medium pH (pH 4.0-5.0 at 45 °C). Ethanol with concentration of 3.4202 g/L was successfully obtained from OFAT analysis under condition of 45 °C and pH 4.5. The significant factors were then statistically optimized using Central Composite Design (CCD) in Response Surface Methodology (RSM). From the data analyzed from Design of Experiment (DoE), at its optimum fermentation conditions (44.83 °C and pH 4.48), the maximal ethanol production obtained is 3.8395 g/L. A validation test with triplicate was performed to validate the actual with predicted value and result in ±1.49% deviation is accepted.
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