Untitled

O’Cleirigh, Cormac C.; Walsh, Padraig K.; O’Shea, Daniel

doi:10.1023/a:1025622100475

Cited by 14 publications

(2 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The number of viable spores in the inoculum can be directly correlated with the size of the filamentous agglomerate regardless of the strain used. Low inoculum sizes result in large, compact pellets, and pellet sizes decrease with increasing inoculum sizes [179,201,202]. Furthermore, vegetative mycelia and matured pellets are commonly used for inoculation in industrial cultivation processes.…”

Section: Biochemical Process Parametersmentioning

confidence: 99%

“…Thus, the development of suitable methods to characterise the morphology of submerged cultures has been the subject of several studies. Whereas earlier efforts mainly involved digital image analysis [177,182,202,221], more recent studies focused on different techniques, including laser diffraction and focused beam reflectance [222]. Microscopic image acquisition and the subsequent analysis of the pictures provide an extensive quantitative description of the fungal morphology, both microand macro-morphological, and, furthermore, the application of advanced imaging techniques such as CLSM [223].…”

Section: Morphology Characterisationmentioning

confidence: 99%

See 1 more Smart Citation

The Taming of the Shrew - Controlling the Morphology of Filamentous Eukaryotic and Prokaryotic Microorganisms

Walisko

Moench-Tegeder

Blotenberg

et al. 2015

Advances in Biochemical Engineering/Biotechnology

View full text Add to dashboard Cite

One of the most sensitive process characteristics in the cultivation of filamentous biological systems is their complex morphology. In submerged cultures, the observed macroscopic morphology of filamentous microorganisms varies from freely dispersed mycelium to dense spherical pellets consisting of a more or less dense, branched and partially intertwined network of hyphae. Recently, the freely dispersed mycelium form has been in high demand for submerged cultivation because this morphology enhances the growth and production of several valuable products. A distinct filamentous morphology and productivity are influenced by the environment and can be controlled by inoculum concentration, spore viability, pH value, cultivation temperature, dissolved oxygen concentration, medium composition, mechanical stress or process mode as well as through the addition of inorganic salts or microparticles, which provides the opportunity to tailor a filamentous morphology. The suitable morphology for a given bioprocess varies depending on the desired product. Therefore, the advantages and disadvantages of each morphological type should be carefully evaluated for every biological system. Because of the high industrial relevance of filamentous microorganisms, research in previous years has aimed at the development of tools and techniques to characterise their growth and obtain quantitative estimates of their morphological properties. The focus of this review is on current advances in the characterisation and control of filamentous morphology with a separation of eukaryotic and prokaryotic systems. Furthermore, recent strategies to tailor the morphology through classical biochemical process parameters, morphology and genetic engineering to optimise the productivity of these filamentous systems are discussed.

show abstract

Section: Biochemical Process Parametersmentioning

confidence: 99%

Section: Morphology Characterisationmentioning

confidence: 99%

The Taming of the Shrew - Controlling the Morphology of Filamentous Eukaryotic and Prokaryotic Microorganisms

Walisko

Moench-Tegeder

Blotenberg

et al. 2015

Advances in Biochemical Engineering/Biotechnology

View full text Add to dashboard Cite

show abstract

Morphological engineering of Streptomyces hygroscopicus var. geldanus: regulation of pellet morphology through manipulation of broth viscosity

O’Cleirigh

Casey

Walsh

et al. 2005

Appl Microbiol Biotechnol

View full text Add to dashboard Cite

Actinomycetes, especially members of the genus Streptomyces, are responsible for producing the majority of known antibiotics. The production of antibiotics by filamentous organisms is often dependent on the morphology and size distribution of the pellet population within the culture. Particle interaction and subsequent pellet formation are primarily dependent on the rate of collision of particles in culture, which is in turn, a function of fluid turbulence. The microbial polysaccharide xanthan gum was used to artificially regulate the apparent viscosity (mu(a)) of S. hygroscopicus fermentation broths with the aim of controlling particle interaction, aggregation and hence pellet formation. An increase in both pellet count and biomass concentration from approximately 2,000 to 8,000 pellets ml(-1) and 0.9-2.1 g l(-1) dry weight of biomass, as well a decrease in the mean pellet volume from 0.014 to 0.004 mm(3) was observed in cultures supplemented with 3 g l(-1) xanthan gum. The addition of xanthan gum significantly alters fluid rheology by increasing the mu(a). Counter-intuitively, an increase in the mu(a) within the experimental range examined resulted in an increase in the rate of gas-liquid mass transfer. This was attributed to the predominantly diffusive nature of oxygen transfer in shake flask cultures.

show abstract

The influence of morphology on geldanamycin production in submerged fermentations of Streptomyces hygroscopicus var. geldanus

Dobson

O’Cleirigh

O’Shea

2008

Appl Microbiol Biotechnol

View full text Add to dashboard Cite

The diverse morphology of the filamentous organism Streptomyces hygroscopicus var. geldanus was characterised by image analysis under various environmental conditions. In the presence of surfactant compounds, a significant decrease in the mean pellet diameter was observed. Cell aggregation was also influenced by spore inoculum level, with high concentrations reducing pellet size. In addition, the dispersion of pellets was found to increase with the inclusion of glass beads to submerged shake-flask cultures. In all cases, production of the secondary metabolite geldanamycin was determined to be dependent on the morphological profile of the organism, with a concomitant increase of 88% in geldanamycin yield observed as the mean pellet diameter was reduced by 70%. Thus, to maximise the yield of geldanamycin, it is necessary to limit pellet formation in Streptomyces hygroscopicus var. geldanus to an appropriate size.

show abstract

Untitled

Cited by 14 publications

References 11 publications

The Taming of the Shrew - Controlling the Morphology of Filamentous Eukaryotic and Prokaryotic Microorganisms

The Taming of the Shrew - Controlling the Morphology of Filamentous Eukaryotic and Prokaryotic Microorganisms

Morphological engineering of Streptomyces hygroscopicus var. geldanus: regulation of pellet morphology through manipulation of broth viscosity

The influence of morphology on geldanamycin production in submerged fermentations of Streptomyces hygroscopicus var. geldanus

Contact Info

Product

Resources

About