Investigation of the influence of Candida tropicalis on bioethanol production using sugarcane bagasse: stochastic and in silico analysis.

This study investigated the impact of Candida tropicalis NITCSK13 on sugarcane bagasse (SCB) consolidated bioprocessing (CSB) using various parameters, such as pH, steam explosion (STEX) pretreatment, and temperature (at two different temperatures, cellulose hydrolysis and ethanol fermentation). The backpropagation neural network (BPNN) method simulated the optimal CSB conditions, achieving a maximum ethanol yield of 44 ± 0.32 g/L (0.443 g of ethanol/g of SCB) from STEX pretreated SCB within 48 h at 55 °C for cellulose hydrolysis and 33 °C for ethanol fermentation and pH 3.5. The simulated conditions were experimentally validated and showed an R2 value of 0.998 and absolute average deviation (AAD) of 1.23%. The strain NITCSK13 also exhibited a high ethanol tolerance of 16% (v/v). The interactions between the inhibitors, cellobiose, furfural, and thermocellulase were assessed through molecular docking. The results revealed a maximum inhibitory constant of 3.7 mM for furfural against the endoglucanase (EnG) of Humicola insolens (2ENG) at 50 °C. Acremonium chrysogenum endoglucanase (5M2D) exhibited a maximum of 88.7 µM for cellobiose at 50 °C. The SWISS homology model of EnG from Candida viswanathii exhibited inhibitory effects similar to those of EnG from Thermoascus and Thermotoga, indicating that the moderately thermophilic yeast Candida sp. cellulase may be capable of efficiently tolerating inhibitors and could be a promising candidate for consolidated bioprocessing of cellulosic ethanol.

An optimized approach towards bio-capture and carbon dioxide sequestration with microalgae Phormidium valderianum using response surface methodology.

As carbon dioxide emissions rise, there's need for alternative strategies, including microorganisms, to capture and mitigate them. The present study investigated on the capability and tolerance of microalgal strain, Phormidium valderianum to capture gaseous CO2 at varying levels (5-30 %). A biomass productivity of 0.0216 ± 0.027 gL-1day-1 and rate of CO2 fixation of 0.035 gL-1day-1 was obtained for 25 % CO2 concentration. From this study, it is evident that higher CO2 levels led to elevated carbohydrate concentration. In addition, protein concentration doubled with the introduction of 25 % CO2. In optimization studies, pH 10, 25 % CO2, and 200 mg/L of Ca(OH)2 concentration was found to be optimal for biomass growth. A higher rate of CO2 fixation of 0.315 gL-1day-1 was achieved at these optimum conditions using response surface methodology. Furthermore, the study demonstrated that microalgae, Phormidium valderianum has the potential to serve as a promising alternative for capturing CO2 emissions.

Process intensification of biopolymer polyhydroxybutyrate production by pseudomonas putida SS9: A statistical approach.

There are numerous elements of daily life where plastic is employed, yet it is uncertain exactly when it will deteriorate. Poly-(3-hydroxybutyrate) (PHB), a biodegradable polymer, is viewed as a possible substitute for synthetic plastics made from petroleum. With Pseudomonas putida SS9, the current study sought to enhance operational conditions and nutritional factors to enhance PHB production. To maximize the impacts of operational factors, a combination of response surface modeling (RSM) and artificial neural networks (ANN) has been applied. PHB content was used as the response while the interaction effects of the factors were examined. The optimal parameters for PHB synthesis were further tested in a lab scale fermentor. Under optimal conditions, 13.83 g/L of C, 0.57 g/L of N, 0.59 g/L of P, the maximal productivity of PHB obtained with Pseudomonas putida SS9 is 12.89 g/L after 84 h. A mean square value of 15.7 with P < 0.0001 were obtained from the ANOVA results of quadratic polynomial model using RSM. The same construct was employed in MATLAB software to train a feed-forward ANN using the back-propagation approach, generating 12.88 g/L. The data indicated that a properly trained ANN model outperforms the RSM model in prediction. Furthermore, employing dairy waste (cheese whey) as a low-cost feedstock resulted in an equally proportionate PHB yield of 12.02 g/L. Therefore, cheese whey appeared to be a viable alternative carbon source over optimized synthetic media.

Efficient removal of lead ions from aqueous solution by graphene oxide modified polyethersulfone adsorptive mixed matrix membrane.

In this study, we report the combined effect of graphene oxide (GO) and polyvinylpyrrolidone (PVP) for the heavy metal removal efficiency of polyethersulfone (PES) membranes. PVP with four different amounts of GO was infused in the membrane matrix by the physical blending method. Characterizations such as porosity, contact angle, water flux and Fourier transform infrared spectroscopy were conducted for all prepared membranes. Viscid behavior of polymer dope solution was examined to understand the phase separation phenomena better. PVP enhanced the GO distribution within the membrane surface to some extent via hydrogen bond. The addition of nanoparticles enhanced the membrane physicochemical properties with water permeation, Pb2+ rejection and adsorption capacity. Permeate flux of modified membrane (m4) was found to be 150.21 L/m2h and it is 8.03 times higher than unmodified membrane (m0). Besides, all fabricated membranes were evaluated for Pb2+ rejection from synthetic wastewater and rejection % of m4 (80.6%) had increased twofold than m0 (38.9%). Membrane cleaning was performed using different methods and the best results were achieved with a concentration of 0.05 wt% sodium hypochlorite under pH 7 and further reused for the filtration test. Moreover, adsorption isotherm was tested using Freundlich and Langmuir models and the Langmuir model offered the best fitting.

Investigation on the utilization of coal washery rejects by different microbial sources for biogenic methane production.

High energy consumption and depletion of fossil fuels lead to the introduction of new technologies to produce alternative fuels with fewer emissions of greenhouse gases. The present investigation was focused to utilize the waste coal washery rejects as a substrate to produce biogenic methane under optimum conditions. Experiments were performed to explore the efficiency of non-coal samples (cow dung, distillery anaerobic digester sludge) and coal mines enriched samples in the degradation of coal washery rejects. Further cow dung, distillery anaerobic sludge, and coal washery rejects were taken at various concentrations to develop anaerobic slurry and analysed for its biogas production. The anaerobic slurry which contains 1:1:1 of cow dung, distillery anaerobic sludge, and coal washery rejects produced methane of around 55.7%. The coal enriched samples showed a maximum of 22.6% of methane. Subsequently, the best methane-producing anaerobic non-coal consortiums were compared with coal enriched microbial culture in converting coal washery rejects of 10 g/l to methane. Results revealed that cow dung inoculum and coal mine enriched inoculum source produced the nearly same amount of methane. This study suggested that the selected anaerobic slurries and coal enriched samples can utilize sub-bituminous coal washery rejects in methane production. Thus, these consortiums can be applied in converting a large amount of coal washery rejects into methane thus can lead to the reclamation of the site.

Exfoliated hydrotalcite-modified polyethersulfone-based nanofiltration membranes for removal of lead from aqueous solutions.

In recent years, the volume of wastewater produced worldwide has led to an increase in the study and use of different membranes and their properties. The progress of membrane technology in hand with nanotechnology has brought to the establishment of advanced membrane materials that are effective in the field of wastewater treatment and water reclamation. This study focuses on the effectiveness of exfoliated hydrotalcite (EHT) nanosheets in the membrane structure which has been evaluated by water flux and heavy metal rejection studies from aqueous solutions. Moreover, the shedding of HT in an organic polar solvent provides a new type of 2-D nanosheet with higher positive charge density. Hydrophilicity, porosity, surface and cross-section morphology, functional groups, and mechanical strength are determined to characterize the prepared membranes. The effect of adding a pore-forming agent to the dope solution is also investigated. Increased hydrophilicity of the modified membranes is confirmed by water contact angle measurement. Furthermore, EHT is found to be an efficient inorganic additive to get better membrane performance and can be employed as a promising candidate for the removal of Pb2+. The rejection % enhanced substantially (50.2% as compared with 29.5% for PES membrane) with increased loading of EHT up to 0.5 g.