Microorganisms In Liquids Research Articles

The utilization of agricultural and livestock waste and the effect on new rice varieties yield on rainfed rice land of Ponjong - Gunungkidul

It is believed that environmentally friendly management of agricultural land through the use of liquid and fermented organic microorganisms can preserve soil fertility, increase the soil microbial population, preserve the environment, as well as increase soil productivity. This research aims to determine the application of various local microorganisms (LMO) to the growth and yield of new rice varieties on the rainfed land of Ponjong-Gunungkidul. Furthermore, it was conducted from February to May 2017, and used a Randomized Completely Block Design (RCBD) with 3 replications and 6 different treatments, namely: M1 = Local Microorganisms of vegetable waste, M2=Local Microorganisms of fruit waste, M3= Local Microorganisms from banana weevils, M4= Local Microorganisms from urine and cow manure, M5 = Local Microorganisms from Gliricidia sp leaves, M6=A mixture of the five local microorganisms ingredients. The results showed that the application of organic fertilizers produced from agricultural and livestock waste and liquid microorganisms was able to increase the total number of the microbial population about seven times on M6 treatment compare to M1 treatment, while the Nitrogen fixation bacteria population and Phosphate solubilizing bacteria increased about six and three times, respectively on the soil rhizosphere. The harvested dry grain yield of the variety Inpari 33 (7.78 tons ha-1) showed a higher yield than that of Inpari Sidenuk and Inpari 19, namely 6.93 tons. ha-1 or 7.13 tons ha. The observation of growth and yield components revealed that the number of tillers, the number of filled grains per panicle, the weight of 1000 grains, and plant biomass showed a significant result and higher differences of Inpari 33 variety than the other 2 varieties used in this research by applying a mixture of five agricultural and livestock wastes ingredients (M6)

Gas phase surface discharge plasma model for yeast inactivation in water

Cold atmospheric plasma is a promising sterilization technology in the food industry. However, there are only a few studies on the process of inactivating microorganisms in liquids, and it is necessary to establish an efficient prediction model before widespread industrial application. In this study, the commercial software COMSOL was used to establish a gas phase surface discharge plasma reactor simulation model, and experiments were subsequently performed to validate the model. Results showed that increasing the initial concentration of yeast in water has a negative effect on the inactivation process. In contrast, yeast inactivation was not significantly affected by reactor diameter changes from 40 mm to 50 mm. The model showed good fit to the experimental data under various operating conditions, and the value of the parameter associated with the reaction coefficients provided insight into the process. This model can be used for process design and improvement of plasma-inactivated liquid foods.

Airborne disinfection using microwave-based technology: Energy efficient and distinct inactivation mechanism compared with waterborne disinfection

Microwave has been extensively applied to inactivate microorganisms in liquids, food, and surfaces. However, energy efficiency is a limiting factor for the environmental application. The utilization pathway and energy efficiency of the microwave in different media have not been investigated. In this study, the inactivation performance, energy utilization, and bactericidal mechanisms for microwave-irradiated airborne and waterborne Escherichia coli were compared. A Beer-Lambert law-based model was also developed and validated to compare the inactivation performance in different phases. Microwave had greater inactivation effect on airborne bacteria than waterborne bacteria. The inactivation rate constant for airborne E. coli (0.29 s−1) was nearly 20 times higher than that of waterborne species (0.014 s−1). Most of the absorbed microwave energy (92.3%) was converted to increase water temperature instead of inactivating the waterborne bacteria, because the microwave photons were easily absorbed by water molecules. By contrast, 45.4% of the absorbed energy could disinfect the airborne bacteria. Finally, the required energies for 1-log inactivation were calculated as 2.3 J and 116.9 J per log-inactivation for airborne and waterborne E. coli, respectively. The airborne and waterborne E. coli samples showed distinct microwave inactivation mechanisms. Waterborne E. coli disinfection was primarily due to thermal effect, while the non-thermal effect was the major mechanism for airborne E. coli inactivation.

Testing a prototype pulse generator for a continuous flow system and its use for E. coli inactivation and microalgae lipid extraction

Among other applications, electroporation is used for the inactivation of pathogens and extraction of substances from microorganisms in liquids where large scale flow systems are used. The aim of our work was therefore to test a pulse generator that enables continuous pulsed electric field (PEF) treatment for Escherichia coli inactivation and microalgae lipid extraction.In the continuous flow PEF system, the flow rate was adjusted so that each bacterial cell received a defined number of pulses. The results of PEF flow treatment showed that the number of pulses influences E. coli inactivation to the same extent as in the previously described cuvette system, i.e., batch system.The continuous flow PEF system was also tested and evaluated for lipid extraction from microalgae Chlorella vulgaris. In control experiments, lipids were extracted via concentration of biomass, drying and cell rupture using pressure or an organic solvent. In contrast, electroporation bypasses all stages, since cells were directly ruptured in the broth and the oil that floated on the broth was skimmed off. The initial experiments showed a 50% oil yield using the electroporation flow system in comparison to extraction with organic solvent.

Whole Cell Imprinting in Sol-Gel Thin Films for Bacterial Recognition in Liquids: Macromolecular Fingerprinting

Thin films of organically modified silica (ORMOSILS) produced by a sol-gel method were imprinted with whole cells of a variety of microorganisms in order to develop an easy and specific probe to concentrate and specifically identify these microorganisms in liquids (e.g., water). Microorganisms with various morphology and outer surface components were imprinted into thin sol-gel films. Adsorption of target microorganism onto imprinted films was facilitated by these macromolecular fingerprints as revealed by various microscopical examinations (SEM, AFM, HSEM and CLSM). The imprinted films showed high selectivity toward each of test microorganisms with high adsorption affinity making them excellent candidates for rapid detection of microorganisms from liquids.

Atmospheric-pressure, nonthermal plasma sterilization of microorganisms in liquids and on surfaces

Abstract Gas discharge plasma inactivation of microorganisms at low (close to ambient) temperature is a promising area of investigation that is attracting widespread interest. This paper describes atmospheric-pressure, nonthermal plasma (NTP) methods for cold sterilization of liquids and thermal sensitive surfaces. These methods are based on the use of direct current (DC) gas discharge plasma sources fed with steady-state high voltage. Parameters characterizing the plasma sources used (plasma-forming gas, gas flow rate, electric power consumed, etc.) are given. The results for plasma sterilization of different microorganisms (vegetative cells, spores, fungi, biofilms) are presented. An empirical mathematical approach is developed for describing NTP inactivation of microorganisms. This approach takes into account not only the destruction of different components of the cells, but their reparation as well.

Killing bacteria present on surfaces in films or in droplets using microwave UV lamps

The killing of bacteria on surfaces by two types of UV sources generated by microwave radiation is described. In both cases, UV radiation is produced by gas-discharge electrodeless lamps (Ar/Hg) excited by microwaves generated by a power supply from a standard domestic microwave oven. For UV lamp excitation, one of these sources makes use of a coaxial line with a truncated outer electrode that allows the excitation of gases and gaseous mixtures over a wide range of pressures at a comparatively low microwave power. In the second source, UV lamps are placed inside a microwave oven. Ultraviolet generated by the two sources was used to destroy vegetative Escherichia coli bacteria dispersed in thin films and in droplets on surfaces. Two types of UV lamps were used in the study. The first was constructed of quartz that filtered UV below 200 nm preventing the dissociation of oxygen in air and, hence, ozone production. The second type of tube was transparent to UV below 200 nm facilitating ozone production in air surrounding it. It was shown that bacterial cells dispersed in films on surfaces are killed more rapidly than cells present in droplets when using the lamps producing ozone and UV radiation. The UV sources described can effect rapid killing and constitute a cost-effective treatment of food and other surfaces, and, the destruction of airborne viruses and bacteria. The lamps can also be utilised for the rapid eradication of microorganisms in liquids.

Inactivation of Saccharomyces cerevisiae with Radio Frequency Electric Fields

The application of radio frequency (RF) electric fields as a nonthermal alternative to thermal inactivation of microorganisms in liquids was investigated. A novel RF system producing frequencies in the range of 20 to 60 kHz was developed. Electric field strengths of 20 and 30 kV/cm were applied to suspensions of Saccharomyces cerevisiae in water over a temperature range of 35 to 55°C. The flow rate was 1.2 liters/min. The S. cerevisiae population was reduced by 2.1±0.1 log units following exposure to a 30-kV/cm field at 40°C. The results of the present study provide the first evidence that strong RF electric fields inactivate microorganisms at moderately low temperatures. Increasing the field strength, the number of treatments, and the temperature enhanced inactivation. Frequency had no effect on inactivation over the range of frequencies studied.

Plasma inactivation of food-related microorganisms in liquids

This paper reports on a plasma process that inactivates microorganisms in liquids through the application of high-voltage pulses. These pulses result in breakdown of the gas and liquid layers, producing many active species such as UV photons, ozone, free radicals and free electrons. Several test microorganisms representing a range of problematic microorganisms were investigated. Significant reductions in microbial population were achieved, demonstrating the effectiveness of using the plasma discharge process to treat contaminated liquids.

Bacterial decontamination of liquids with pulsed electric fields

The effect of pulsed electric fields on the viability of microorganisms, mainly bacteria, in liquids has been studied since the 1960's. Experimental results obtained over a large range of electrical and microbiological parameters, point towards an irreversible formation of pores in the cell membrane as the mechanism for lysing. The model of membrane pore formation seems to fail only for ultrashort electrical pulses, where intracellular effects, and possibly resonant effects, might dominate. This paper presents an overview of the effect of pulsed electric fields on the viability of microorganisms in liquids, In particular, the lytic effect of variations in the electrical pulse parameters, such as pulse shape, amplitude, duration, and single shot vs. repetitive operation, is described, A major application of the pulsed electric field method is 'cold' bacterial decontamination of liquid food and drinking water. The energy consumption for complete bacterial decontamination is presently 100 to 400 kJ/l. A possible reduction of the required energy by utilizing intracellular electric field interactions and resonance effects is discussed.

A fast pulsed power source applied to treatment of conducting liquids and air

Two pilot pulsed power sources were developed for fundamental investigations and industrial demonstrations of treatment of conducting liquids. The developed heavy-duty power sources have an output voltage of 100 kV (rise time 10 ns, pulse duration 150 ns, pulse repetition rate maximum 1000 pps). A pulse energy of 0.5-3 J/pulse and an average pulse power of 1.5 kW have been achieved with an efficiency of about 80%. In addition, adequate electromagnetic compatibility is achieved between the high-voltage pulse sources and the surrounding equipment. Various applications, such as the use of pulsed electric fields (PEFs) or pulsed corona discharges for inactivation of microorganisms in liquids or air, have been tested in the laboratory. For PEF treatment, homogeneous electric fields in the liquid of up to 70 kV/cm at a pulse repetition rate of 10-400 pps could be achieved. The inactivation is found to be 85 kJ/L per log reduction for Pseudomonas fluorescens and 500 kJ/L per log reduction for spores of Bacillus cereus. Corona directly applied to the liquid is found to be more efficient than PEF. With direct corona we achieve 25 kJ/L per log reduction for both Gram positive and Gram negative bacteria. For air disinfection using our corona pulse source, the measured efficiencies are excellent: 2 J/L per log reduction.

Inactivating microorganisms using a pulsed electric field continuous treatment system

High-voltage pulsed electric fields (PEFs) can be used to inactivate microorganisms in liquids. Applying PEF technology to food pasteurization is a promising nonthermal method, which may radically change food preservation processes and provide consumers with microbiologically safe, minimally processed, fresh-like products. A continuous-flow system in a laboratory-size prototype was constructed for the nonthermal pasteurization of liquid foods with PEF technology. Major components in the prototype include a high-voltage repetitive pulse generator, a coaxial liquid food treatment chamber, a fiber-optic temperature sensing instrument and a data acquisition system. Microbial inactivation tests were conducted in the continuous PEF treatment system. Repetitive high-voltage pulses with an exponential decaying waveshape were applied to the liquid food which was pumped through the treatment chamber. Test microorganisms selected for inactivation were Escherichia coli, Staphylococcus aureus and Saccharomyces cerevisiae. Over 6-order-of-magnitude reductions in the viability of selected microorganisms were achieved while the food temperature was maintained below 40/spl deg/C.

Activated sludge treatment of food‐processing wastewater with bioaugmentation

Evaluates the effect of bioaugmentation on the activated sludge treatment of food wastewaters including those containing potato, starch, sugar and milk. Parameters of study include live liquid microorganisms, dosage, aeration time and wastewater strength. Concludes that bioaugmentation with addition of live liquid micro‐organisms improves total organic carbon (TOC) removal efficiency and reduces sludge production. Aerobic bioaugmentation is effective in TOC removal from potato, sugar and milk wastewater but not effective in the case of starch wastewater.

Effect of bioaugmentation on activated sludge treatment of potato wastewater

The purpose of this study was to determine the effect of an aerobic bioaugmentation process on the activated sludge treatment of potato wastewater. Parameters investigated included types of live liquid microorganisms (LLMO), aeration time, LLMO dosage and wastewater strength. Types of LLMO included S‐l, G‐l, E‐l, N‐l and NEW‐1. TOC (total organic carbon) and MLVSS (mixed liquor volatile suspended solids) were determined during the bench scale aerobic batch activated sludge reactor study. Results showed that bioaugmentation with LLMO addition had an important effect on both TOC removal efficiency and sludge reduction. S‐l LLMO was the most effective, while N‐l or E‐l was the least effective LLMO in the batch activated sludge treatment of potato wastewater. The best TOC removal efficiency obtained was 98%, while the best sludge reduction obtained was 67% in terms of initial MLVSS concentration.

A New Automatic System to Evaluate the Density of Viable Microorganisms in Liquids

Summary A new automatic system for the evaluation of microbial densities based on the dilution method principle is presented. This new system will be called MW (from MicroWell) system in the following text. The MW system is designed to be completely automatic and is therefore more practical, timesaving and allows a more uniform and reproducible sample processing than the common manual methods. Bifidobacterium adolescentis was used as the test organism, for which a selective medium was developed. The experimental data show that by the MW system microbial densities can be reliably determined and results can be achieved which are in good agreement with theory. The coincidence of the results with those derived from the plating method suggests that the statistical model guiding this system is reasonable and close to reality. Based on the assumption that, as usual, the possible microbial densities of the samples may vary between very low and very high values and that no prior knowledge is available about the range of this value, the accuracy of the conventional plating method and of the MW system is discussed: under certain conditions the conventional plating method is theoretically more favourable. But generally the accuracy of the MW system is at least comparable or even superior to the accuracy of the conventional plating method and should be more than sufficient for a variety of applications.