Bioconversion

Microbial enzymes have significant biotechnological application in industries. The purpose of this study was to
isolate and identify microorganisms associated with millet cobs, determine the enzyme activity (lipase, protease,
pectinase, cellulase and amylase) of the millet cob samples, screen the isolated microorganisms for enzyme
production and determine the physicochemical parameters of the degrading medium. A total of seven bacteria and
twelve fungi consisting of yeasts and moulds were isolated during the study. Day 20 of the degradation period has
the highest enzyme activity for all the enzymes in the degraded millet cobs; lipase has the highest enzyme activity
with a value of 0.496 mg/mL/min while protease has the lowest with a value of 0.003 mg/mL/min. All of the isolated microorganisms exhibited enzymatic activity except Zygosaccharomyces rouxii in which Bacillus spp were screened positive for all the enzymes assayed for. The temperature (ºC), pH and titratable acidity (%) ranged from 24.03-28.47, 3.81-6.50 and 2.31-4.21 respectively. This study contributes to catalogue of microorganisms that has been identified as enzyme producers and provides additional information to support future research about the industrial potential of these microorganisms that may produce enzymes and other metabolites of industrial importance.

The aim of this work was to evaluate the feasibility of using pear pomace as a substrate for the commercial cultivation of two strains of Pleurotus ostreatus (Pl-P and Pl-J) and to analyze the variation of the chemical composition of the biodegraded pomace. The Pl-J strain presented 98,3% of Biological Efficiency, 35% of Yield and 45 days of Productive Period, while for Pl-P the values were 62,3%, 21,8% and 35 days respectively. The metabolic activity of both strains on the substrate led to a relative decrease in dry matter and organic matter content of 20 to 30%, and 60% for soluble carbohydrates (p<0,05). At the end of the Productive Period, the fibers (FDN, FDA and LDA) decreased 10 to 20% while the crude protein content was not significantly modified.

El objetivo de este trabajo fue evaluar los cambios en la composición química de residuos (orujos) de las industrias procesadoras de peras de la región del Valle Medio de Río Negro durante la etapa de crecimiento vegetativo de Pleurotus ostreatus.
Se analizó la composición química del orujo de pera luego de permitir el desarrollo micelial de dos cepas de P. ostreatus (Pl-P y Pl-J) en cajas de Petri, en oscuridad a 28°C durante 2 meses. Se determinó el % de materia seca como índice del % de Bioconversión, contenido de materia orgánica por incineración en mufla, sustancias nitrogenadas por Kjeldahl, fibra detergente neutro (FDN), fibra detergente ácido (FDA) y lignina en detergente ácido (LDA) por el método de Van Soest y carbohidratos no estructurales con reactivo antrona-ácido sulfúrico.
Si bien el ensayo se prolongó durante 60 días, las cepas de Pleurotus estudiadas lograron colonizar en forma completa las cajas de Petri al cabo de 12 días.
Los resultados obtenidos evidenciaron una disminución de la materia seca inicial obteniéndose un 30% de Bioconversión promedio para las cepas analizadas. Estos resultados muestran que el proceso de bioconversión por hongos de pudrición blanca como P. ostreatus constituye una metodología alternativa para reducir el impacto ambiental generado por la acumulación de estos residuos agroindustriales.
La caracterización química del orujo de pera biodegradado evidenció una considerable disminución respecto al orujo sin biodegradar en los contenidos netos de materia seca (16,14 ± 1,41 g vs 11,28 ± 1,03 g), materia orgánica (15,79 ± 1,38 g vs. 10,93 ± 0,94 g) y de carbohidratos no estructurales (0,71 ± 0,06 g vs. 0,31 ± 0,03 g), no evidenciándose diferencias asociadas a las cepas estudiadas. Por su parte, los valores correspondientes al contenido neto de sustancias nitrogenadas y fibras (FDN, FDA y LDA) si bien fueron menores con respecto al orujo sin biodegradar, las diferencias fueron menos pronunciadas. Cabe destacar que la expresión de los resultados de la caracterización química en base a porcentaje de materia seca muestra variaciones menos apreciables, dada la marcada disminución de este valor durante la bioconversión

El objetivo de este trabajo fue evaluar la factibilidad de emplear orujo de pera como sustrato para el cultivo comercial de dos cepas de Pleurotus ostreatus (Pl-P y Pl-J) y analizar la variación de la composición química del orujo biodegradado. La cepa Pl-J presentó 98,3% de Eficiencia Biológica, 35% de Rendimiento y 45 días de Período Productivo, mientras que para Pl-P los valores fueron 62,3%, 21,8% y 35 días, respectivamente. La actividad metabólica de ambas cepas sobre el sustrato provocó una disminución relativa del contenido de materia seca y materia orgánica del 20 al 30% y de un 60% para los carbohidratos solubles. Al finalizar el Período Productivo, las fibras (FDN, FDA y LDA) disminuyeron 10 a 20% mientras que el contenido de proteína bruta no se modificó significativamente. The aim of this work was to evaluate the feasibility of using pear pomace as a substrate for the commercial cultivation of two strains of Pleurotus ostreatus (Pl-P and Pl-J) and to analyze the variatio...

Resumen Debido al gran volumen de residuos de frutas que se generan diariamente en diversas operaciones relacionadas con el procesamiento de frutas, verduras, entre otros, y las actividades económicas de origen agroindustrial, se plantea que es posible realizar la digestión anaeróbica de estos residuos biodegradables. Es por esta razón que la investigación tiene como finalidad discutir las bases teóricas que fundamentan el aprovechamiento de los residuos sólidos orgánicos de las frutas mediante procesos de digestión anaerobia. En la actualidad los residuos sólidos orgánicos (fracción húmeda) de la industria no tienen un objetivo específico para su uso, la mayoría de ellos son enviados al basurero. Dada la necesidad de aprovechar los residuos de cáscaras de frutas se requieren biorreactores debidamente diseñados y construidos. El uso de combinaciones de residuos sólidos orgánicos de las frutas en procesos de digestión anaeróbica puede potenciar la producción o rendimiento de metano y a su vez generar mayor productividad y factibilidad desde la perspectiva económica. En este sentido, la piña y naranja pueden ser evaluadas para determinar la relación óptima para obtener mayores rendimientos de producción energética (metano).

Palabras clave: bioconversión, metano, subproductos, frutas, digestión anaerobia.

The increase in human population with the increase in nutritional awareness for fruits and vegetables consumption is forcing toward higher production and supply of fruits and vegetables. However, some sorts of food processing steps are involved before human consumption which is essential for preserving the properties of those fruits and vegetables. During these processes and till reaching the consumers, many fruits and vegetables wastes are produced. Although the emphasis was given to produce less waste and reuse the products as much as possible, utilization of those wastes in bioprocessing and production of different value-added products were less emphasized. Thus, in this chapter, we describe the major value-added bioproducts produced from fruits and vegetables wastes such as bioactive compounds, phenolic compounds, enzymes, pigments, flavoring compounds and aroma, dietary fibers, organic acids, bioenergy, bioplastics, exopolysaccharides, single-cell protein, etc.

Optically active 2-(4-hydroxyphenylcarbamoyloxymethyl)-l-methyl-I, 2, 5, 6-tetrahydropyridine is obtained on microbiological transformation of 1-methyl-2-(N-phenvl-carbamoyloxymethyl)-l,2,5,6-tetrahydropyridine with a growing culture of the fungus C. verticillata VKPM F-430. Transformation of 2-(2-phenylethyl)pyridine by a methanoxidating culture of Methylococcus occurs either by hydroxvlation of the side chain or conversion of the substrate into N-oxide, depending on the process conditions.

Biological lignin valorization represents an emerging green approach to upgrade lignin for sustainable and economic biorefineries. However, lignin generally exhibits poor water solubility and inhomogeneous distribution in an aqueous medium, significantly limiting its bioconversion efficiency. Herein, we develop a novel alkali sterilization strategy to effectively enhance the dispersion and fermentation performance of lignin substrates. The colloidal particle size and molecular structure variations of lignin during the sterilization were thoroughly investigated to reveal the mechanisms of enhanced fermentation performance. Results showed that alkali sterilization achieved a completely aseptic effect when mixing lignin medium at an initial pH of 12.7 for 24 h. Dynamic light scattering (DLS) analysis demonstrated that the hydrodynamic volume of colloidal lignin particles decreased by 96.3% by alkali sterilization compared with the conventional thermal sterilization. Moreover, lignin characterizations by nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC) suggested that alkali sterilization modified the lignin molecular structure by generating 50% more hydrophilic carboxyl groups, reducing the weight-average molecular weight (M w) by 23.0%, and narrowing the molar-mass dispersity (Đ M) by 23.8%. The generation of lignin substrates with more uniform distribution and lower molecular weight improved Rhodococcus opacus PD630 cell growth and metabolism. Microbial cell amount, lignin degradation, and lipid production in alkali sterilized medium increased by 309%, 30.3%, and 48.3%, respectively, compared to those in thermally sterilized medium. These results clearly demonstrated that alkali sterilization dramatically improved the lignin bioconversion performance. This work presents a facile and effective sterilization strategy to overcome inhomogeneous lignin distribution in aqueous fermentation media, showing great potentials as a platform technique for promoting biological lignin valorization.

For the first time the potential of Noctiluca scintillans, a non-toxic mixotrophic dinoflagellate, in bioconverting and/or excreting saxitoxin has been illustrated, thus contributing to the limited knowledge on the aspects of toxin pathways in the food chain/web and predator-prey preferences. Noctiluca growth rate increased with higher Pyrodinium concentration but the ratio of Noctiluca to Pyrodinium should at least be 1:250 cells per mL. Noctiluca fed with Pyrodinium alone was found to decrease in number suggesting that the nutrients from this prey were insufficient. This was confirmed by the improved cell density of Noctiluca upon addition of 0.01% casitone to the Pyrodinium-fed Noctiluca. The alternative prey (Gymnodinium sanguineum) slowed down the grazing impact of Noctiluca on Pyrodinium. Noctiluca depleted Gymnodinium earlier than Pyrodinium showing preference over a prey with less saxitoxin. After the feeding experiments, total saxitoxin levels decreased to 72% in the Noctiluca–Pyrodinium setup whereas no saxitoxin was detected in the Noctiluca culture fed with Pyrodinium and G. sanguineum. It is possible that Gymnodinium can provide some nutrients needed to make Noctiluca more efficient in bioconverting saxitoxin.

The aim of this work was to evaluate the feasibility of using pear pomace as a substrate for the commercial cultivation of two strains of Pleurotus ostreatus (Pl-P and Pl-J) and to analyze the variation of the chemical composition of the biodegraded pomace. The Pl-J strain presented 98,3% of Biological Efficiency, 35% of Yield and 45 days of Productive Period, while for Pl-P the values were 62,3%, 21,8% and 35 days respectively. The metabolic activity of both strains on the substrate led to a relative decrease in dry matter and organic matter content of 20 to 30%, and 60% for soluble carbohydrates (p&lt;0,05). At the end of the Productive Period, the fibers (FDN, FDA and LDA) decreased 10 to 20% while the crude protein content was not significantly modified.

Plant growth promoting rhizobacteria (PGPR) are strains of naturally occurring soil bacteria that live in close vicinity to the plant’s rhizosphere region which possess the capability to augment host growth. This study was conducted to isolate and identify potential PGPR isolates indigenous to Metroxylon sagu, Rottb. rhizosphere. These potential isolates were characterised based on their beneficial plant growth promoting (PGP) properties and identified by molecular analysis via 16S rDNA sequencing. A total of 18 isolates were successfully isolated, out of which five isolates were tested, and designated as (S1A, S2B, S3A, S3C and S42). Among the five isolates, two isolates (S2B and S3C) were found to produce high levels of indole-3-acetic acid (2.96 μg/mL and 10.31 μg/mL), able to fix nitrogen and show significant activity in phosphate solubilisation. The analysis of their sequences via National Center for Biotechnology Information (NCBI) suggested their close identity towards Lysini...

We generalize literature data on transformation of aromatic and hydrogenated heterocycles. We show that in some cases, the processes have been accomplished regioselectively and stereoselectively in preparative yields. By microbiological transformation we mean incomplete conversion of organic compounds by enzymes of microorganisms, accompanied by accumulation of the conversion products in the medium. The reactions are accomplished by one or several enzymes and do not lead to significant changes in the structure of the substrate [1]. The products of partial conversion (transformation) of many organic compounds exhibit valuable practical properties. Furthermore, the chemical industry and biotechnology need to draw on microbiological methods to solve ecology problems on the one hand and on the other hand to search for sufficiently simple methods for synthesis of compounds which are difficult to obtain by chemical means [1, 2]. Biotransformation is less laborious and more economical than chemical reactions, and also ensures high regioselectivity and stereoselectivity of the reactions. Accordingly, capital investment in this area has become more advisable, since the demand is increasing for many compounds obtained by the biotransformation method for organic synthesis, the biotechnology and pharmacology industries (for example, the demand for optically active intermediates) [3-4]. The advantages of the microbiological transformation method over chemical reactions include the following. 1. The specificity of action of enzymes, which makes it possible to accomplish very f'me rearrangement of molecules of organic compounds using simple processing schemes, while the analogous chemical conversions usually require laborious multistep syntheses. 2. The "mild" conditions of action of the enzymes, since the latter function usually in aqueous nonaggressive media and at a temperature no higher than 100°C. 3. The moderate amounts of wastes and byproducts which are harmful for the biosphere [5].