Proizvodnja α-amilaze na podlozi od poljoprivrednih otpadaka s pomoću bakterije Bacillus amyloliquefaciens

The productivity of enzyme fermentations depends critically on maintaining a high oxygen transfer rate to satisfy the optimal oxygen demand of the microorganism for product formation. Among the several factors that affect oxygen transfer rates in a fermentor are the air flow rate and agitation. The production of α-amylase by Bacillus amyloliquefaciens was performed in 600-mL and 5-litre fermentor with a working volume of 300 mL and 3 L, respectively. The experiments indicated a requirement of high rates of aeration to enhance the enzyme yield. The biomass yield and productivity of the enzyme were found to have a linear relationship with the air flow rate, and the highest productivity was observed at 1.0 vvm. A maximum productivity of 41.4 U/(mL·h) was obtained after 14 h of fermentation in 600-mL fermentor system and a comparable productivity of 40 U/(mL·h) was obtained after 12 h in the 5-litre fermentor.Učinkovitost fermentacijske proizvodnje enzima ponajprije ovisi o optimalnoj opskrbi mikroorganizma kisikom, tj. dobrom prijenosu kisika. Protok zraka i miješanje su neki od čimbenika koji utječu na opskrbu reaktora kisikom. S pomoću Bacillus amyloliquefaciens proizvedena je α-amilaza u reaktoru zapremnine 600 mL, radnog volumena od 300 mL, i u reaktoru od 5 L, s radnim volumenom od 3 L. Utvrđeno je da je često prozračivanje reaktora povećalo prinos enzima. Prinos biomase i produktivnost enzima bili su u linearnom odnosu s protokom zraka, a najveća je produktivnost bila pri 1 vvm. Maksimalna je produktivnost od 41,4 U/(mL·h) postignuta nakon 14 h u fermentoru od 600 mL, dok je u onom od 5 L najveća produktivnost bila 40 U/(mL·h) nakon 12 sati fermentacije

Heterologous expression of genes for bioconversion of xylose to xylonic acid in Corynebacterium glutamicum and optimization of the bioprocess

Sundar L, Susmitha A, Rajan D, et al. Heterologous expression of genes for bioconversion of xylose to xylonic acid in Corynebacterium glutamicum and optimization of the bioprocess. AMB Express. 2020;10: 68

Fusarium biocontrol: antagonism and mycotoxin elimination by lactic acid bacteria

Mycotoxins produced by Fusarium species are secondary metabolites with low molecular weight formed by filamentous fungi generally resistant to different environmental factors and, therefore, undergo slow degradation. Contamination by Fusarium mycotoxins in cereals and millets is the foremost quality challenge the food and feed industry faces across the globe. Several types of chemical preservatives are employed in the mitigation process of these mycotoxins, and they help in long-term storage; however, chemical preservatives can be used only to some extent, so the complete elimination of toxins from foods is still a herculean task. The growing demand for green-labeled food drives to evade the use of chemicals in the production processes is getting much demand. Thus, the biocontrol of food toxins is important in the developing food sector. Fusarium mycotoxins are world-spread contaminants naturally occurring in commodities, food, and feed. The major mycotoxins Fusarium species produce are deoxynivalenol, fumonisins, zearalenone, and T2/HT2 toxins. Lactic acid bacteria (LAB), generally regarded as safe (GRAS), is a well-explored bacterial community in food preparations and preservation for ages. Recent research suggests that LAB are the best choice for extenuating Fusarium mycotoxins. Apart from Fusarium mycotoxins, this review focuses on the latest studies on the mechanisms of how LAB effectively detoxify and remove these mycotoxins through their various bioactive molecules and background information of these molecules

Lipoglycans Contribute to Innate Immune Detection of Mycobacteria

Innate immune recognition is based on the detection, by pattern recognition receptors (PRRs), of molecular structures that are unique to microorganisms. Lipoglycans are macromolecules specific to the cell envelope of mycobacteria and related genera. They have been described to be ligands, as purified molecules, of several PRRs, including the C-type lectins Mannose Receptor and DC-SIGN, as well as TLR2. However, whether they are really sensed by these receptors in the context of a bacterium infection remains unclear. To address this question, we used the model organism Mycobacterium smegmatis to generate mutants altered for the production of lipoglycans. Since their biosynthesis cannot be fully abrogated, we manipulated the biosynthesis pathway of GDP-Mannose to obtain some strains with either augmented (∼1.7 fold) or reduced (∼2 fold) production of lipoglycans. Interestingly, infection experiments demonstrated a direct correlation between the amount of lipoglycans in the bacterial cell envelope on one hand and the magnitude of innate immune signaling in TLR2 reporter cells, monocyte/macrophage THP-1 cell line and human dendritic cells, as revealed by NF-κB activation and IL-8 production, on the other hand. These data establish that lipoglycans are bona fide Microbe-Associated Molecular Patterns contributing to innate immune detection of mycobacteria, via TLR2 among other PRRs

In Situ Compatibilization of Biopolymer Ternary Blends by Reactive Extrusion with Low-Functionality Epoxy-Based Styrene Acrylic Oligomer

[EN] The present study reports on the use of low-functionality epoxy-based styrene¿acrylic oligomer (ESAO) to compatibilize immiscible ternary blends made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polylactide (PLA), and poly(butylene adipate-co-terephthalate) (PBAT). The addition during melt processing of low-functionality ESAO at two parts per hundred resin (phr) of biopolymer successfully changed the soften inclusion phase in the blend system to a thinner morphology, yielding biopolymer ternary blends with higher mechanical ductility and also improved oxygen barrier performance. The compatibilization achieved was ascribed to the in situ formation of a newly block terpolymer, i.e. PHBVb- PLA-b-PBAT, which was produced at the blend interface by the reaction of the multiple epoxy groups present in ESAO with the functional terminal groups of the biopolymers. This chemical reaction was mainly linear due to the inherently low functionality of ESAO and the more favorable reactivity of the epoxy groups with the carboxyl groups of the biopolymers, which avoided the formation of highly branched and/or cross-linked structures and thus facilitated the films processability. Therefore, the reactive blending of biopolymers at different mixing ratios with low-functionality ESAO represents a straightforward methodology to prepare sustainable plastics at industrial scale with different physical properties that can be of interest in, for instance, food packaging applications.This research was funded by the EU H2020 project YPACK (Reference number 773872) and by the Spanish Ministry of Science, Innovation, and Universities (MICIU) with project numbers MAT2017-84909-C2-2-R and AGL2015-63855-C2-1-R. L. Quiles-Carrillo wants to thank the Spanish Ministry of Education, Culture, and Sports (MECD) for financial support through his FPU Grant Number FPU15/03812. Torres-Giner also acknowledges the MICIU for his Juan de la Cierva contract (IJCI-2016-29675).Quiles-Carrillo, L.; Montanes, N.; Lagaron, J.; Balart, R.; Torres-Giner, S. (2019). In Situ Compatibilization of Biopolymer Ternary Blends by Reactive Extrusion with Low-Functionality Epoxy-Based Styrene Acrylic Oligomer. 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Mycobacterial <img src='/image/spc_char/beta.gif' border=0>-Lactamases: An Overview

342-345Despite of four decades of effective chemotherapy, tuberculosis has re-emerged as one of the leading causes of death. Prevention and control of tuberculosis got a great setback by the appearance of multidrug resistant strains of M. tuberculosis. New antibiotic regiments are needed for the treatment of multidrug resistant tuberculosis. -Lactam antibiotics that inhibit trans peptidase reactions and prevent cell wall assembly in bacteria are the most widely used antimicrobial agents. However, most of the mycobacteria are naturally resistant to -lactams,presumably because of their extremely hydrophobic cell wall, presence of periplamsic penicillin binding proteins (PPHS) and most importantly the presence of an active -lactamase.This paper details the various studies on -lactamasesof Mycobacterium and highlights the importance of -lactamases,in future, for developing an effective drug combination comprising a -lactamantibiotic in combination with -lactamaseinhibitors

Studies on exopolysaccharide production by probiotic Lactic acid bacteria

The thesis mainly discussed the isolation and identification of a probiotic Lactobacillus plantarum, fermentative production of exopolysaccharide by the strain, its purification, structural characterisation and possible applications in food industry and therapeutics. The studies on the probiotic characterization explored the tolerance of the isolated LAB cultures to acid, bile, phenol, salt and mucin binding. These are some of the key factors that could satisfy the criteria for probiotic strains . The important factors required for a high EPS production in submerged fermentation was investigated with a collection of statistical and mathematical approach. Chapter 5 of the thesis explains the structural elucidation of EPS employing spectroscopic and chromatographic techniques. The studies helped in the exploration of the hetero-polysaccharide sequence from L. plantarum MTCC 9510. The thesis also explored the bioactivities of EPS from L. plantarum. As majority of chemical compounds identified as anti-cancerous are toxic to normal cells, the discovery and identification of new safe drugs has become an important goal of research in the biomedical sciences. The thesis has explored the anti-oxidant, anti-tumour and immunomodulating properties of EPS purified from Lactobacillus plantarum. The presence of (1, 3) linkages and its molecular weight presented the EPS with anti-oxidant, anti-tumour and immunomodulating properties under in vitro conditions.Cochin University of science and TechnologyDivision of Biotechnology,National Institute for Interdisciplinary science and Technology, Thiruvananthapura