Medium optimization for enhanced production of Rifamycin B by Amycolatopsis mediterranei S699: Combining a full factorial design and a statistical approach

Suitability assessment of dumpsite soil biocover to reduce methane emission from landfills under interactive influence of nutrients

Biocovers are known for their role as key facilitator to reduce landfill methane (CH₄) emission on improving microbial methane bio-oxidation. Methanotrophs existing in the aerobic zone of dumped wastes are the only known biological sinks for CH₄ being emitted from the lower anaerobic section of landfill sites and even from the atmosphere. However, their efficacy remains under the influence of landfill environment and biocover characteristics. Therefore, the present study was executed to explore the suitability and efficacy of dumpsite soil as biocover to achieve enhanced methane bio-oxidation under the interactive influence of nutrients, carbon source, and environmental factors using statistical-mathematical models. The Placket-Burman design (PBD) was employed to identify the significant factors out of 07 tested factors having considerable impact on CH₄ bio-oxidation. The normal plot and Student's t test of PBD indicated that ammonical nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃^--N), methane (CH₄), and copper (Cu) concentration were found significant. A three-level Box-Behnken design (BBD) was further applied to optimize the significant factors identified from PBD. The BBD results revealed that interactive interaction of CH₄ with NH₄⁺-N and NO₃^--N affected the CH₄ bio-oxidation significantly. The sequential statistical approach predicted that maximum CH₄ bio-oxidation of 27.32 μg CH₄ h^-1 could be achieved with CH₄ (35%), NO₃^--N (250 μg g^-1), NH₄+-N (25 μg g^-1), and Cu (50 mg g^-1) concentration. Conclusively, waste dumpsite soil could be a good alternative over conventional soil cover to improve CH₄ bio-oxidation and lessen the emission of greenhouse gas from waste sector.

Elemental Analysis of Human Blood Serum by Microwave Plasma-Investigation of the Matrix Effects Caused by Sodium Using Model Solutions

Human blood is a complex sample matrix when elemental analysis is considered. In this study, the effects of Na, a natural component of serum samples, was investigated in the quantitative determination of Ca, K, Mg, Cu, Zn, and Fe by microwave plasma atomic emission spectrometry. The robustness of the microwave plasma was tested by evaluating MgII 280.271 nm/MgI 285.213 nm by varying two adjustable operating parameters, the read time, and the nebulizer pressure. The read time has no influence on the robustness while the MgII/MgI ratio decreased when the nebulizer pressure was increased during the analysis. The threshold concentrations of the interfering Na were determined at the analytical lines used for the measurement of other elements. The matrix effect of the commercially available microwave plasma was studied by a series of model experiments with human blood. The increasing concentration of Na in the matrix within the normal ranges reported for blood serum increased the intensities of the measured atomic lines. According to a factorial design-where two applied factors were the concentration of Na matrix and the measured elements as well as their levels were considered as factorial points-it was found that the Na concentration in a serum sample after acid digestion and 10 times dilution affected the intensity values of the measured elements. For Ca, Cu, and Fe, a statistically significant effect was observed, while for Zn, Mg, and K, an interaction effect was also found. However, after calculating the percentage errors caused by the shift, the relative difference was observed to be quite small (< 10%).

Optimization of β-galactosidase Production by Batch Cultures of Lactobacillus leichmannii 313 (ATCC 7830™)

The endoenzyme β-galactosidase (β-d-galactoside galactohydrolase; EC 3.2.1.23) has been used at industrial scales for the preparation of lactose-free milk and for the conversion of lactose to galacto-oligosaccharides (GOS) prebiotics. In this study, using Plackett–Burman (PB) design and the response surface methodology (RSM), the batch growth conditions for the production of β-galactosidase in DeMan-Rogosa-Sharpe (MRS) media have been studied and optimized for Lactobacillus leichmannii 313 (ATCC 7830™) for the first time. The incubation temperature (30  <  T  <  55 °C), starting pH (5.5  <  pH  <  7.5), and carbon source (glucose, lactose, galactose, fructose, and sucrose) were selected as the significant variables for optimization. The maximum crude β-galactosidase production (measured by specific activity) was 4.5 U/mg proteins and was obtained after 12 h of fermentation. The results of the PB design and further optimization by RSM showed that the initial pH of 7.0 and 15.29 g/L of lactose were the levels that gave the optimum observed and predicted β-galactosidase activities of 23.13 U/mg and 23.40 U/mg, respectively. Through RSM optimization, β-galactosidase production increased significantly (over five-fold) in optimized medium (23.13 U/mg), compared with unoptimized medium (4.5 U/mg). Moreover, the crude enzyme obtained was able to hydrolyze lactose and also produce galacto-oligosaccharides. Because its ability to produce β-galactosidase was significantly improved through optimization by RSM, L. leichmannii 313 can serve as a potential source of β-galactosidase for food applications at an industrial scale.

Optimization of Medium Composition for the Production of Neomycin by Streptomyces fradiae NCIM 2418 in Solid State Fermentation

Neomycin production of Streptomyces fradiae NCIM 2418 was optimized by using response surface methodology (RSM), which is powerful mathematical approach comprehensively applied in the optimization of solid state fermentation processes. In the first step of optimization, with Placket-Burman design, ammonium chloride, sodium nitrate, L-histidine, and ammonium nitrate were established to be the crucial nutritional factors affecting neomycin production significantly. In the second step, a 2⁴ full factorial central composite design and RSM were applied to determine the optimal concentration of significant variable. A second-order polynomial was determined by the multiple regression analysis of the experimental data. The optimum values for the important nutrients for the maximum were obtained as follows: ammonium chloride 2.00%, sodium nitrate 1.50%, L-histidine 0.250%, and ammonium nitrate 0.250% with a predicted value of maximum neomycin production of 20,000 g kg⁻¹ dry coconut oil cake. Under the optimal condition, the practical neomycin production was 19,642 g kg⁻¹ dry coconut oil cake. The determination coefficient (R²) was 0.9232, which ensures an acceptable admissibility of the model.

Development of balanced medium composition for improved rifamycin B production by isolated Amycolatopsis sp. RSP-3

AIM

To develop optimum fermentation environment for enhanced rifamycin B production by isolated Amycolatopsis sp. RSP-3.

METHODS AND RESULTS

The impact of different fermentation parameters on rifamycin B production by isolated Amycolatopsis sp. RSP-3 was investigated using Taguchi methodology. Controlling fermentation factors were selected based on one variable at a time methodology. The isolated strain revealed more than 25% higher production compared to literature reports. Five different nutritional components (soyabean meal, glucose, potassium nitrate, calcium carbonate and barbital) and inoculum concentration showed impact on rifamycin B production at individual and interactive level. At optimized environment, 65% contribution was observed from selected fermentation parameters.

CONCLUSIONS

Soyabean meal and calcium carbonate were the most significant factors among the selected factors followed by barbital and potassium nitrate. Glucose, however, showed the least significance on rifamycin B production with this strain. A maximum of 5.12 g l(-1) rifamycin B production was achieved with optimized medium containing (g l(-1)) soyabean meal, 27; glucose, 100; potassium nitrate, 4; calcium carbonate, 3 and barbital, 1.2.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present study signifies identification of balanced medium component concentrations for improved rifamycin B production by isolated Amycolatopsis sp. RSP-3. This strain requires organic and inorganic nitrogen sources for effective product yield. Yet at individual level, organic nitrogen source has c. nine-fold higher influence compared to inorganic one.