బయోప్రాసెసింగ్ & బయోటెక్నిక్స్ జర్నల్

For developing a feasible world we need to reduce the utilization of fossil fuels and also the pollutant production. These two aims can be fulfilled by treating the waste like sewage sludge. Sewage sludge is a perfect substrate for power generation as they rich in organic substance. This study consolidated bio-cathode with in a dual chamber MFC to generate voltage from sewage sludge (2 L) at a maximum voltage generated of 2.5 V. The use of bio cathode generates an internal resistance of 36-46 ohm, hence yielding maximum voltage generation (2.5 V) from MFC. Saccharomyces cerevisiae sp. was used as biocatalyst. Methylene blue (10 ml) was used a mediator and potassium ferricyanide (350 ml) was used as an oxidizing agent for the conversion of sewage sludge into voltage generation. In this MFC, anode solution was in batch and cathode was in continuous mode of operation under optimum conditions of the operating parameters like pH, oxygen flow rate and substrate concentration.

Electrical energy needs in Pakistan are expected to continue to rise. The use of petroleum as a source of energy still dominates, although oil reserves in Pakistan are increasingly being depleted. Therefore, there is a need to develop alternative source of sustainable energy, such as Microbial Fuel Cell (MFC). MFC shows another type of renewable energy by changing natural matter into power with the help of microbes. In the present study, varied salt concentrations of a salt bridge in novel MFC design were analyzed. Sewage sludge was utilized, which contains a lot of organic materials and is additionally one of the major sources of ecological contamination, as substrate MFC. Saccharomyces cerverciae sp. (44 g) was used as a biocatalyst. Methylene blue (10 ml) was used as a mediator and potassium ferricyanide (100 ml) was used as an oxidizing agent for the conversion of sewage sludge into voltage generation using lab-scale double chamber MFC. Varied salt concentrations (1M, 3M and 5M of KCl and NaCl) of salt concentrations of salt bridge in a novel MFC design were analyzed. The maximum generated voltage, current, power, power density and current density with 1M KCl were 0.451 V, 0.0451, 0.0175561 mW, 0.000226001 mW/m2, 10.5166661 μA/m2 respectively. The MFC was run for a period of 1 day and readings were noted at regular intervals. The results obtained were helpful in designing an optimized MFC.

Enterococcus gallinarum CRL 1826 isolated from an American bullfrog (Lithobates catesbeianus) skin inhibits the growth of Citrobacter freundii, Pseudomonas aeruginosa (bullfrog pathogens) and Listeria monocytogenes by a synergistic effect between organic acids and a bacteriocin-like molecule. This bacteriocin, named enterocin CRL 1826, showed a proteinaceous nature, heat stability and polar characteristics. Its production followed kinetics of primary metabolites synthesis reaching a maximum of 61,400 AU/mL. The minimum inhibitory and minimum bactericidal concentrations were 2,640 and 5,280 AU/mL, respectively, against L. monocytogenes. The addition of 120,000 AU/mL of enterocin to growing L. monocytogenes and Gram-negative (P. aeruginosa and C. freundii) bacteria showed bactericidal and bacteriostatic effects, respectively. However, enterocin derived-peptides had bactericidal effect only against Gram-negatives.

Enterocin produced cell envelope damages and efflux of citosolic content on L. monocytogenes, while enterocin derived-peptides showed granulation and contraction of cytoplasm material on P. aeruginosa and increase in the periplasmic space and empty cells appearance on C. freundii.

Enterocin CRL 1826 is the first bacteriocin described for E. gallinarum from raniculture. It could be used as a biopreservative while the derived-peptides represent an alternative to control multi-drug resistant Gram-negatives. The antimicrobial spectrum and the stability of enterocin and its derived-peptides indicate that they could be applied in different biotechnological areas.

Phytases, pectinases, and invertases are three major industrially important enzymes that find significant applications in food, feed, pharmaceutical and environmental sectors. The six isolated fungal species (JUIT, 1-6), isolated from soil Waknaghat, HP, have been identified as Aspergillus sp. through microscopical studies and fruiting body formation. Identified fungal isolates have been screened for multienzymes (Invertase, Pectinase and Phytase) production through solid state and Submerged Fermentations. Among all the fungal strains screened, Aspergillus nidulans (JUIT 4) and Aspergillus niger (JUIT 5) showed the highest coproduction of multi enzymes through Solid State Fermentation using wheat bran and maltose as a substrate and inducer, respectively. The Solid State Fermentation conditions seems to be equal to 2 ml spore suspension, 90% relative humidity, 0.4% water activity and 48 h incubation time. Partial purified (through 70% ammonium sulphate precipitation) enzymes have been further characterized for effect of pH. The resultant multienzymes complex with phytase, pectinase, and invertase activities may have considerable industrial potential in food and feed industries for fruit juice clarification, phytate elimination and in condiment preparations.

Modern winemaking industry has new challenges focused on the application of preserved starter’s microbial cultures for the optimization of the fermentation process that ensuring flavor characteristics and the reproducibility of the final products obtained. Thus, the aim of the present work was to select the inoculation conditions for preselected Saccharomyces cerevisiae mc₂ (SC), Kloeckera apiculata mF (KA) and Oenococcus oeni X₂L (OO) after freeze-drying and storage in both pure and mixed cultures. The strains were grown in 17% Natural Grape Juice (NGJ) and then lyophilized in 10% individual sugars (glucose, fructose, sucrose, maltose and trehalose), 2.4% sodium glutamate, 4% yeast extract and NGJ by using different culture combinations: 1)- pure cultures (KA1, SC1, OO1), 2)- mixed yeast cultures (KA2, SC2), 3)- mixed microbial cultures (KA3, SC3, OO3). After lyophilization, the strains were stored for 12 months at 4 and 25°C. Viability post-lyophilization was culture/lyoprotectant-dependent while survival to storage depended on time and temperature being O. oeni the more resistant strain to the all process, then K. apiculata and S. cerevisiae, respectively. Freeze-drying of mixed KA-SC in 10% fructose and OO in 17% NGJ up to 6 months of storage at 4°C were the best conditions for the maintenance of the fermentative properties of the strains and for glycerol production. The inoculation of grape musts with KA-SC and OO lyophilized individually with low-cost lyoprotectants would ensure the proper development of the fermentation processes and glycerol synthesis, thus increasing the organoleptic characteristics of wines by a non-Saccharomyces strain. Therefore, the starter culture should include K. apiculata, S. cerevisiae and O. oeni strains.

Malaysia is known to be one of the largest palm oil producers and also generates huge amounts of oil palm biomass, which is mainly treated as bio waste. One of the efficient methods to recycle this potential oil palm biomass could be gasification technology. Gasification is a process involving conversion of solid carbonaceous fuel into combustible gas using directly heated biomass. From processing of Fresh Fruit Bunch (FFB) (a biomass example), Empty Fruit Bunch (EFB) fibre, shell etc. are produced. In this study, a laboratory scale fluidized bed was developed, an appropriate fibre/shell composition ratio was studied and analysis on profiles of gas produced in the oil palm biomass fluidized bed gasifier was conducted. The effects of fibre/shell composition ratio and rate of reaction on temperature profiles were investigated. Temperature reaction rate and calorific value of oil palm biomass with gas compositions were also analyzed.

Electrical energy needs in Pakistan are expected to continue to rise. The use of petroleum as a source of energy still dominates, although oil reserves in Pakistan are increasingly being depleted. Therefore, there is a need to develop alternative source of sustainable energy, such as, Microbial Fuel Cell (MFC). MFC shows another type of renewable energy by changing natural matter into power with the help of microbes. In the current study, an attempt has been made to find the effect of molar concentration of salt bridge on electron transferring potential and to find the efficiency of bioelectricity generation by yeasts such as Hansenula anomala and Saccharomyces cerevisiae. Maximum current of 1.9 mV and 1.4 mV was generated by yeasts Hansenula anomala and Saccharomyces cerevisiae in 1M potassium chloride salt bridge with duration of 96 hrs. This work also demonstrates the feasibility of using yeasts Hansenula anomala and Saccharomyces cerevisiae for current generation, in a mediator less MFC. During the metabolism the fuels like glucose gets oxidized when they pass through the metabolic cycle. The possibility of alternative sources is one particular method of generating power is with the help of microbial fuel cell, which can minimize the usage of fossil fuels. MFCs can produce energy directly from biomass (electricity production) or producing hydrogen from biomass (fuel production). Biological fuel cell converts the chemical energy of carbohydrates such as sugar and alcohol indirectly into electrical energy.