ah Abdul Khalil

Optimization of milk-based medium for efficient cultivation of Bifidobacterium pseudocatenulatum G4 using face-centered central composite-response surface methodology

This study was undertaken to optimize skim milk and yeast extract concentration as a cultivation medium for optimal Bifidobacteria pseudocatenulatum G4 (G4) biomass and β-galactosidase production as well as lactose and free amino nitrogen (FAN) balance after cultivation period. Optimization process in this study involved four steps: screening for significant factors using 23 full factorial design, steepest ascent, optimization using FCCD-RSM, and verification. From screening steps, skim milk and yeast extract showed significant influence on the biomass production and, based on the steepest ascent step, middle points of skim milk (6% wt/vol) and yeast extract (1.89% wt/vol) were obtained. A polynomial regression model in FCCD-RSM revealed that both factors were found significant and the strongest influence was given by skim milk concentration. Optimum concentrations of skim milk and yeast extract for maximum biomass G4 and β-galactosidase production meanwhile low in lactose and FAN balance after cultivation period were 5.89% (wt/vol) and 2.31% (wt/vol), respectively. The validation experiments showed that the predicted and experimental values are not significantly different, indicating that the FCCD-RSM model developed is sufficient to describe the cultivation process of G4 using skim-milk-based medium with the addition of yeast extract.

Effects of Ultrasound Assisted Extraction in Conjugation with Aid of Actinidin on the Molecular and Physicochemical Properties of Bovine Hide Gelatin

Actinidin was used to pretreat the bovine hide and ultrasonic wave (53 kHz and 500 W) was used for the time durations of 2, 4 and 6 h at 60 °C to extract gelatin samples (UA2, UA4 and UA6, respectively). Control (UAC) gelatin was extracted using ultrasound for 6 h at 60 °C without enzyme pretreatment. There was significant (p < 0.05) increase in gelatin yield as the time duration of ultrasound treatment increased with UA6 giving the highest yield of 19.65%. Gel strength and viscosity of UAC and UA6 extracted gelatin samples were 627.53 and 502.16 g and 16.33 and 15.60 mPa.s, respectively. Longer duration of ultrasound treatment increased amino acids content of the extracted gelatin and UAC exhibited the highest content of amino acids. Progressive degradation of polypeptide chains was observed in the protein pattern of the extracted gelatin as the time duration of ultrasound extraction increased. Fourier transform infrared (FTIR) spectroscopy depicted loss of molecular order and degradation in UA6. Scanning electron microscopy (SEM) revealed protein aggregation and network formation in the gelatin samples with increasing time of ultrasound treatment. The study indicated that ultrasound assisted gelatin extraction using actinidin exhibited high yield with good quality gelatin.

Autolysis of bovine skin, its endogenous proteases, protease inhibitors and their effects on quality characteristics of extracted gelatin

The autolysis of pretreated bovine skin (PBS) (treated with 0.1 M NaOH and 1% HCl), its endogenous proteases, inhibitors and their effects on quality attributes of gelatin were examined. PBS was subjected to different temperatures (20-90 °C) and pH (2-9) and treated with different protease inhibitors. Maximum autolytic activity of PBS was observed at 40 °C and pH 5. Ethylene-bis (oxyethylenenitrilo) tetraacetic acid (EGTA) was the most effective in impeding the degradation of γ-, β- and α- chains of PBS protein indicating that metallocollagenases were the predominant endogenous proteases in bovine skin. Gelatin was extracted in the absence (GAE) and presence (GPE) of EGTA, and EGTA with papain enzyme (GPEP). GPEP had a higher yield and lower gel strength than GEA and GPE. Metallocollagenases partook in the degradation of gelatin thereby affecting its functional properties. Pretreating PBS with or without EGTA, and papain influenced the quality attributes of gelatin.

Organic Acids and Carbon Profiles by Bifidobacteria Pseudocatenulatum G4 During Cultivation in Low Concentrations of Milk Medium

Growth characteristics of Bifidobaceria pseudocatenulatum G4 in low concentration milk medium were studied. During cultivation process, profiles of cell growth, pH changes, organic acids and sugar profile were monitored. A finding showed that final cell concentration (cfumL-1) obtained in 2 and 4% (w/v) milk concentration was two times lower than in comparative media. However, 6% (w/v) skim milk gave a promising media for B. pseudocatenulatum G4 growth. Organic acids production (acetic, lactic, formic and citric acid) by strains was detected in all milk medium concentrations and similar profile were observed. Except for formic acid which actively produced in 2 and 4% (w/v) milk concentration. The accumulation of formic acids was believed due to carbon limitation. As for sugar profile, co-metabolized galactose and glucose were observed in 2, 4 and 6% (w/v) skim milk concentration. Meanwhile high carbon remains occurred in 8 and 10% (w/v) milk concentrations after cultivation period. Among all concentrations, milk with 6% (w/v) concentration showed better support for cells growth without formic acid presence and low carbon remains at the end of cultivation period.

Screening of Medium with Different Range of Waste Frying Oil (WFO), Sodium Nitrate (NaNO 3 ) and Sodium Chloride (NaCl) for Biosurfactant Production by Thermophilic Anoxybacillus sp. Using Fractional Factorial Design (FFD)

In this study, culture medium was optimized for economic production of biosurfactant by Anoxybacillus sp. using different waste frying oil, sodium nitrate, and sodium chloride concentrations. Screening step was performed using the Design-Expert software (2 level full factorial design). The response variables are of value for surface tension reduction in the cell-free-culture medium as it indicates the biosurfactant production. The yield of biosurfactant was found to be the highest when surface tension was at the lowest value (42.30 mN/m) at a temperature of 55 °C, agitation 130 rpm, 9 % (v/v) waste frying oil (WFO), 0.5 % (w/v) sodium nitrate (NaNO3), and 0.02 % (w/v) of sodium chloride (NaCl). The biosurfactant was observed to stable in the face of exposure to extreme temperature changes, pH conditions, and salinity. These physiochemical properties demonstrate the potential for using waste frying oil as an inexpensive material for biosurfactant production.