scholarly journals Novel Capsular Polysaccharide from Lobochlamys segnis

2021 ◽  
Vol 2 (1) ◽  
pp. 121-137
Author(s):  
Gino Schiano di Visconte ◽  
Michael J. Allen ◽  
Andrew Spicer
Keyword(s):  
Extracellular Polymeric Substances ◽  
Capsular Polysaccharide ◽  
Acetic Acid Solution ◽  
Reducing Power ◽  
Ph Control ◽  
Stress Conditions ◽  
Random Coil ◽  
Efficient Production ◽  
Average Molecular Mass ◽  
Extraction And Purification

In recent years there has been a significant effort from food, nutraceutical, cosmeceutical, pharmaceutical, and biomedical industries to discover and develop new natural ingredients. Microalgae have been recognised as potential sources of high value chemicals, with most attention focused upon antioxidants, pigments, and specialty oils. An under-exploited group of biochemicals produced by microalgae are extracellular polymeric substances (EPS). Lobochlamys segnis (formerly called Chlamydomonas segnis) was previously reported to produce a large amount of capsular polysaccharide (CPS) closely related to hyaluronan (HA) under stress conditions. In this work, the purified CPS was characterised and shown to have an average molecular mass (Mn) of about 3.7 MDa, and displayed a highly branched random coil structure unlike the simple repeating linear HA polysaccharide. Chemical analysis showed the presence of galactose, glucuronic acid, and glucose sugars confirming that the product has a different composition to that of HA. Mixotrophic growth and stress conditions were identified and improved upon with a pH control system using acetic acid solution to induce efficient production of CPS. Extraction and purification conditions were also identified exploiting the high Mn of the product. The CPS showed thickening properties and both significant antioxidant capacity and reducing power, which could have commercial applications. This is the first report on the characterization of this novel polysaccharide with non-Newtonian properties similar to HA.

scholarly journals Mannitol Is Required for Stress Tolerance in Aspergillus niger Conidiospores

2003 ◽  
Vol 2 (4) ◽  
pp. 690-698 ◽  
Author(s):  
George J. G. Ruijter ◽  
Maarten Bax ◽  
Hema Patel ◽  
Simon J. Flitter ◽  
Peter J. I. van de Vondervoort ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Carbon Source ◽  
Cell Damage ◽  
Reducing Power ◽  
Dry Weight ◽  
Stress Conditions ◽  
Prolonged Storage ◽  
Developmentally Regulated ◽  
In The Wild ◽  
Major Metabolic Pathway

ABSTRACT d-Mannitol is the predominant carbon compound in conidiospores of the filamentous fungus Aspergillus niger and makes up 10 to 15% of the dry weight. A number of physiological functions have been ascribed to mannitol, including serving as a reserve carbon source, as an antioxidant, and to store reducing power. In this study, we cloned and characterized the A. niger mpdA gene, which encodes mannitol 1-phosphate dehydrogenase (MPD), the first enzyme in the mannitol biosynthesis pathway. The mpdA promoter contains putative binding sites for the development-specific transcription factors BRLA and ABAA. Furthermore, increased expression of mpdA in sporulating mycelium suggests that mannitol biosynthesis is, to a certain extent, developmentally regulated in A. niger. Inactivation of mpdA abolished mannitol biosynthesis in growing mycelium and reduced the mannitol level in conidiospores to 30% that in the wild type, indicating that MPD and mannitol 1-phosphate phosphatase form the major metabolic pathway for mannitol biosynthesis in A. niger. The viability of spores after prolonged storage and germination kinetics were normal in an mpdA null mutant, indicating that mannitol does not play an essential role as a reserve carbon source in A. niger conidia. However, conidiospores of a ΔmpdA strain were extremely sensitive to a variety of stress conditions, including high temperature, oxidative stress and, to a lesser extent, freezing and lyophilization. Since mannitol supplied in the medium during sporulation repaired this deficiency, mannitol appears to be essential for the protection of A. niger spores against cell damage under these stress conditions.

Novel pH control strategy for efficient production of optically active l -lactic acid from kitchen refuse using a mixed culture system

2016 ◽  
Vol 216 ◽  
pp. 52-59 ◽  
Author(s):  
Yukihiro Tashiro ◽  
Shota Inokuchi ◽  
Pramod Poudel ◽  
Yuki Okugawa ◽  
Hirokuni Miyamoto ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Mixed Culture ◽  
Control Strategy ◽  
Culture System ◽  
Ph Control ◽  
Optically Active ◽  
Efficient Production

scholarly journals Modifying the Cyanobacterial Metabolism as a Key to Efficient Biopolymer Production in Photosynthetic Microorganisms

2020 ◽  
Vol 21 (19) ◽  
pp. 7204
Author(s):  
Maciej Ciebiada ◽  
Katarzyna Kubiak ◽  
Maurycy Daroch
Keyword(s):  
Carbon Metabolism ◽  
Extracellular Polymeric Substances ◽  
Carbon Fixation ◽  
Tricarboxylic Acid Cycle ◽  
Central Carbon Metabolism ◽  
Efficient Production ◽  
Heterotrophic Microorganisms ◽  
Central Carbon ◽  
Polymeric Compounds ◽  
Metabolic Properties

Cyanobacteria are photoautotrophic bacteria commonly found in the natural environment. Due to the ecological benefits associated with the assimilation of carbon dioxide from the atmosphere and utilization of light energy, they are attractive hosts in a growing number of biotechnological processes. Biopolymer production is arguably one of the most critical areas where the transition from fossil-derived chemistry to renewable chemistry is needed. Cyanobacteria can produce several polymeric compounds with high applicability such as glycogen, polyhydroxyalkanoates, or extracellular polymeric substances. These important biopolymers are synthesized using precursors derived from central carbon metabolism, including the tricarboxylic acid cycle. Due to their unique metabolic properties, i.e., light harvesting and carbon fixation, the molecular and genetic aspects of polymer biosynthesis and their relationship with central carbon metabolism are somehow different from those found in heterotrophic microorganisms. A greater understanding of the processes involved in cyanobacterial metabolism is still required to produce these molecules more efficiently. This review presents the current state of the art in the engineering of cyanobacterial metabolism for the efficient production of these biopolymers.

scholarly journals Vibrio alginolyticus influences quorum sensing-controlled phenotypes of acute hepatopancreatic necrosis disease-causing Vibrio parahaemolyticus

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11567
Author(s):  
Panida Paopradit ◽  
Natta Tansila ◽  
Komwit Surachat ◽  
Pimonsri Mittraparp-arthorn
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Vibrio Parahaemolyticus ◽  
Extracellular Polymeric Substances ◽  
Capsular Polysaccharide ◽  
Regulatory Gene ◽  
Challenge Test ◽  
Great Ability ◽  
Acute Hepatopancreatic Necrosis Disease ◽  
Reporter Bacteria

Background Acute hepatopancreatic necrosis syndrome (AHPND) caused by Vibrio parahaemolyticus strain (VPAHPND) impacts the shrimp industry worldwide. With the increasing problem of antibiotic abuse, studies on quorum sensing (QS) system and anti-QS compounds bring potential breakthroughs for disease prevention and treatment. Methods In this study, the cell-free culture supernatant (CFCS) and its extract of V. alginolyticus BC25 were investigated for anti-QS activity against a reporter bacteria, Chromobacterium violaceum DMST46846. The effects of CFCS and/ or extract on motility, biofilm formation and extracellular polymeric substances (EPSs) of VPAHPND PSU5591 were evaluated. Moreover, the effects of V. alginolyticus BC25 on virulence of VPAHPND PSU5591 were investigated by shrimp challenge test. The potentially active anti-QS compounds presented in the extract and effect on gene expression of VPAHPND PSU5591 were identified. Results The CFCS of V. alginolyticus BC25 and its extract showed a significant anti-QS activity against the reporter bacteria as well as swimming and swarming motilities, biofilms, and EPSs production by VPAHPND PSU5591. Transcriptome analysis revealed that V. alginolyticus BC25 extract significantly reduced the flagella genes involved in biofilm formation and iron-controlled virulence regulatory gene of VPAHPND PSU5591. Whereas, the LuxR family transcriptional regulator gene, c-factor, a cell-cell signaling gene, and capsular polysaccharide were up-regulated. The potentially active anti-QS compounds identified in extract were Cyclo-(L-Leu-L-Pro), and Cyclo-(L-Phe-L-Pro). Furthermore, V. alginolyticus BC25 enhanced disease resistance against VPAHPND PSU5591 in tested shrimp larvae. Conclusion These findings suggest that V. alginolyticus BC25 could provide natural anti-QS and anti-biofilms compounds and has great ability to be used as biocontrol agent against VPAHPND infection in shrimp aquaculture.

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