Immobilization Techniques

Application of microbial inoculants into the soil
can enhance soil properties and plant nutrient
acquisition and increase the efficiency of mineral
fertilizers and manures. The potential use
of microbial inoculants in sustainable agriculture
and soil restoration has been gaining
increasing interest. Encapsulation of beneficial
soil microorganisms has been applied and used
in the agricultural industry, particularly in processes
such as spray drying, interfacial polymerization,
or cross-linking. This chapter
presents different techniques for microbial
inoculants and their benefits for agricultural
and environmental purposes. Techniques
include fluidized bed, coacervation, and ionic
or inverse gelation. The major topics discussed
are conventional inoculants, formulation of
microbial inoculants, encapsulation techniques,
and application trends. In addition, the use of
biochar as inoculant carrier is proposed in order
to develop new formulations. This innovative
microbial inoculant has many advantages, such
as increased water-holding capacity, high internal
porosity, and large surface area, while it also
provides a suitable habitat for microorganisms
to enhance colonization and bacteria protection
in the soil.

The development of biosensors has seen recent growth owing to their wide range of potential applications from the defending of bioterrorism to the detection of various diseases. Recent investigations in highly sensitive nanomaterials containing nanotechnology suggest the possibility of its advanced applications as biosensors in different biomedical fields. Besides highlighting the characteristic features of different classes of advanced biosensor across different fields of potential application, this article gives a clear overview of some specific investigations related to the surface immobilizations of piezoelectric biosensors employing effective materials and advanced technologies. Further, the current development of piezoelectric biosensors in the detection of potential biomolecules for advanced biomedical applications is critically reviewed. The qualitative and quantitative sensitivity of piezoelectric biosensors, various expressions of resonant frequency shift with changes in mass, thickness, density, and stress for piezoelectric materials are distinctly explored. The importance of several novel nanomaterials for the detection of various diseased biomolecules is clearly illustrated. This study concludes that proper selection of materials is potential to bring improvement in quality as well as reduction in cost of advanced biosensor devices. © 2013 by ESG.

http://electrochemsci.org/papers/vol8/80608863.pdf

The availability of starch from inexpensive sources such as agro-wastes and agricultural byproducts, added to a large-scale production of amylolytic enzymes, facilitates the production of syrups containing glucose, fructose or maltose, which are of considerable importance in the pharmaceutical and food industries.

This study aimed to produce a glucose syrup from an agricultural by-product i.e. wheat bran; using amylase immobilization in calcium alginate beads. To improve the amylase production of the two used strains Bacillus sp. R2 and Bacillus cereus, a continuous immobilization in 2% calcium alginate beads was conducted. The best amylase activity (421,73U/ml) was obtained after 20 h with Bacillus cereus. The hydrolysis product analyzed by thin layer chromatography TLC was predominantly identified as glucose and xylose. The obtained results showed a great potential of the two Bacillus species to produce amylases, also the entrapped enzymes gave significantly higher hydrolysis activity compared to free amylases.

Levan production in batch and continuous fermentation systems by Zymomonas mobilis B-14023 wasinvestigated. The culture medium used in both of the fermentation systems contained sucrose and vari-ous organic nitrogen sources. Maximum concentration of levan was produced with yeast extract amongthe nitrogen sources tested. Response surface methodology was used to investigate the effects of threefactors on the concentration of levan in batch cultures of Z. mobilis. Maximum levan concentration was40.2 g/L and this concentration was reached at the optimum levels of process variables, which were299.1 g/L initial substrate concentration, 42.3 h incubation time, and initial pH 6.0. Continuous fermenta-tion experiments were done in packed bed bioreactor using Ca-alginate immobilized Z. mobilis cells. The highest levan concentration (31.8 ± 0.21 g/L) was obtained at a dilution rate of 0.14 h−1while maximum volumetric productivity (6.556 g/(L h)) was obtained at a dilution rate of 0.22 h−1. Increasing the dilutionrate resulted in decreased levan and increased residual sugar concentrations.

Citation/Citar este artículo como: Delgadillo Rodríguez IP, Montenegro Ruíz LC, Pinilla Agudelo GA, Melgarejo LM. Medición de la fluorescencia de la clorofila a en algas encapsuladas en alginato de calcio. Acta biol. Colomb. 2017;22(2):199-208. DOI: http:// dx.doi.org/10.15446/abc.v22n2.56166 RESUMEN La inmovilización de las algas tiene múltiples aplicaciones, tales como la biorremediación del agua y la producción de metabolitos. Una de las variables que se puede determinar en las algas inmovilizadas es la fluorescencia de la clorofila a, debido a que este parámetro está relacionado con la respuesta fisiológica de estos organismos. Por ello, el objetivo de este estudio fue explorar un método para la medición de la fluorescencia de la clorofila a en algas encapsuladas en esferas de alginato de calcio. Con este fin, se cultivaron dos especies de microalgas (Scenedesmus ovalternus LAUN 001 y Parachlorella kessleri LAUN 002) en monocultivos, tanto en condiciones de cultivo libres (10 mL de la preparación algal en 250 mL de Medio Básico de Bold), como encapsuladas (250 esferas de alginato de calcio en 250 mL de Medio Básico de Bold). Se realizaron diferentes protocolos de medición de la fluorescencia de la clorofila a del fotosistema II (PSII) variando a) el tiempo de preadaptación a la oscuridad (10, 15 y 30 min), b) la intensidad de luz generada por fluorómetro no modulado (entre 1000 y 3500 µmoles m-2 s-1), y c) el tiempo de exposición a la luz actínica (1, 2 y 5 s). Se lograron establecer como condiciones óptimas para la medición de la eficiencia cuántica potencial del fotosistema II (F v /F m) en las algas encapsuladas las siguientes: a) 30 min de preadaptación a la oscuridad; b) 3000 µmoles m-2 s-1 , de intensidad lumínica generada desde el fluorómetro; y c) 1 o 2 s de exposición a la luz actínica. Se encontraron los siguientes valores en la F v /F m en condiciones no estresantes: 0,760 a 0,764 para S. ovalternus y 0,732 a 0,748 para P. kessleri. Esta metodología permite observar algunos cambios en la actividad fotoquímica relacionados con variaciones de los factores bajo los cuales se encuentran las algas inmovilizadas. Palabras clave: algas inmovilizadas, eficiencia cuántica potencial del fotosistema II, microalgas, Parachlorella kessleri, Scenedesmus ovalternus. ABSTRACT Immobilization of algae has many applications, such as water bioremediation and production of metabolites. One of the variables that can be determined in the immobilized algae is chlorophyll a fluorescence, because this parameter is related to the physiological response of these organisms. Therefore, the objective of this study was to explore a method for measuring the chlorophyll a fluorescence in calcium alginate-encapsulated algae. To do this, two species of microalgae (Scenedesmus ovalternus LAUN 001 and Parachlorella kessleri LAUN 002) were grown in monocultures in both free culture conditions (10 mL of algae preparation in 250 mL of Basal Bold Medium) and encapsulated (250 spheres in 250 mL of Basal Bold Medium). Different measurement protocols of chlorophyll a fluorescence of photosystem II (PSII) were performed by varying a) the preadaptation time to darkness (10, 15 and 30 min), b) the light intensity of the non-modulated fluorometer (between 1000 and 3500 μmoles m-2 s-1), and c) the time of exposure to actinic light (1, 2 and 5 s). The optimal conditions for the measurement of the maximum quantum yield of PSII (F v /F m) in encapsulated algae were established as follow: a) 30 min of preadaptation time; b) 3000 μmoles m-2 s-1 of the fluorometer light intensity; and c) 1 to 2 s of exposure to actinic light. The following values in the photochemical activity of algae in non-stressful conditions were found: 0.760

This is the first study to produce three-dimensional (3D) cellulose from any plant up to now. This 3D cellulose was produced from Astragalus gummifer (Fabaceae) trunk by using a modified method in which original the shape of cellulose was kept as natural. This novel 3D cellulose was characterized by SEM, TGA, FT-IR, XRD and elemental analysis to evidence the purity and to compare it with commercially available cellulose from cotton. Results from these characterizations were found convincing because almost the same physicochemical properties were observed for both newly obtained 3D cellulose and commercial one. Both fibers and pores on the surface of 3D cellulose were observed. Thanks to its diversified surface morphology, this novel 3D cellulose was tested for its protein adsorption performance and the results were compared with commercial cellulose as follows: maximum adsorption capacity at pH 8.0 was recorded as 59.2 mg/g for 3D cellulose while 29.6 mg/g for commercial cellulose. According to this result, it is clear to say that this sorbent has high affinity for lysozyme. Also this 3D cellulose could be useful for the other areas of separation science.

The whole-cell immobilization on chitosan matrix was evaluated. Bacillus sp., as producer of CGTase, was grown in solid-state and batch cultivation using three types of starches (cassava, potato and cornstarch). Biomass growth and substrate consumption were assessed by flow cytometry and modified phenol–sulfuric acid assays, respectively. Qualitative analysis of CGTase production was determined by colorless area formation on solid culture containing phenolphthalein. Scanning electron micro-scopy (SEM) analysis demonstrated that bacterial cells were immobilized on chitosan matrix efficiently. Free cells reached very high numbers during batch culture while immobilized cells maintained initial inoculum concentration. The maximum enzyme activity achieved by free cells was 58.15 U ml-1 (36 h), 47.50 U ml-1 (36 h) and 68.36 U ml-1 (36 h) on cassava, potato and cornstarch, respectively. CGTase activities for immobilized cells were 82.15 U ml-1 (18 h) on cassava, 79.17 U ml-1 (12 h) on potato and 55.37 U ml-1 (in 6 h and max 77.75 U ml-1 in 36 h) on cornstarch. Application of immobilization technique increased CGTase activity significantly. The immobilized cells produced CGTase with higher activity in a shorter fermentation time comparing to free cells.

We have investigated two approaches to enhance and extend H2 photoproduction yields in heterocystous, N2-fixing cyanobacteria entrapped in thin alginate films. In the first approach, periodic CO2 supplementation was provided to alginate-entrapped, N-deprived cells. N-deprivation led to the inhibition of photosynthetic activity in vegetative cells and the attenuation of H2 production over time. Our results demonstrated that alginate-entrapped dhupL cells were considerably more sensitive to high light intensity, N-deficiency and imbalances in C:N ratios than the wild-type cells. In the second approach, Anabaena PCC 7120, it's dhupL mutant and Calothrix 336/3 films were supplemented with N2 by periodic treatments of air, or air + CO2. These treatments restored the photosynthetic activity of the cells and led to a high level of H2 production in Calothrix 336/3 and dhupL (except for the air + CO2 treatment) but not in the Anabaena PCC 7120 strain (for which H2 yields did not change after air treatments). The highest H2 yield was obtained by the air treatment of dhupL cells. Notably, the supplementation of CO2 under an air atmosphere led to prominent symptoms of N-deficiency in dhupL, but not in the wild-type strains. We propose that the uptake hydrogenase in heterocystous cyanobacteria not only supports nitrogenase activity by removing excess O2 from heterocysts, but also indirectly protects the photosynthetic apparatus of vegetative cells from photoinhibition, especially under stressful conditions that cause an imbalance in the C:N ratio of cells.