Systems Approaches to Predict the Functions of Glycoside Hydrolases during the Life Cycle of Aspergillus niger Using Developmental Mutants ∆brlA and ∆flbA

Eumelanin type pigments are synthesized at all the stages of the life cycle of the fly Hermetia illucens: in the larvae, pre-pupae, pupae and adult flies (dead flies). The greatest content of melanin was recorded in the cuticles. Melanin was present not only in the cuticle, hence it remained in the cuticle after the emergence of the adult fly. It was also found in the insect body in a complex with lipids. In pupae, it is mostly lauric acid that was associated with melanin. Its proportion in the melanin-chitosan complex was 80%. The isolated melanin-chitosan complex of adult flies showed a wide range of antibacterial activity, inhibiting the growth of 21 out of the 25 of the test cultures. The melanin-chitosan complex of empty pupal membranes and alcohol suspension of pupal melanin inhibited twice as smaller number of test cultures and the above activity was absolutely in the pupal chitosan. The largest zone of growth inhibition was recorded with respect to Aspergillus niger, Candida albicans, salmonella, and Staphylococcus aureus. An alcohol suspension of pupal melanin inhibited the growth of 10 test cultures. In this case the greatest activity was shown in relation to Mycobacterium B5 and Acinetobacter sp. 1182.

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Submerged Conidiation and Product Formation by Aspergillus niger at Low Specific Growth Rates Are Affected in Aerial Developmental Mutants

Applied and Environmental Microbiology ◽

10.1128/aem.00118-11 ◽

2011 ◽

Vol 77 (15) ◽

pp. 5270-5277 ◽

Cited By ~ 21

Author(s):

Thomas R. Jørgensen ◽

Kristian F. Nielsen ◽

Mark Arentshorst ◽

JooHae Park ◽

Cees A. van den Hondel ◽

...

Keyword(s):

Aspergillus Niger ◽

Nutrient Limitation ◽

Growth Rates ◽

Specific Growth ◽

Product Formation ◽

Submerged Cultivation ◽

Developmental Mutants ◽

Aerial Hyphae ◽

Submerged Conidiation ◽

Specific Growth Rates

ABSTRACTExposure to an aerial environment or severe nutrient limitation induces asexual differentiation in filamentous fungi. Submerged cultivation ofAspergillus nigerin carbon- and energy-limited retentostat cultures both induces and fuels conidiation. Physiological and transcriptomic analyses have revealed that this differentiation strongly affects product formation. Since conidiation is inherent in the aerial environment, we hypothesized that product formation near zero growth can be influenced by affecting differentiation or development of aerial hyphae in general. To investigate this idea, three developmental mutants (ΔfwnA,scl-1, andscl-2mutants) that have no apparent vegetative growth defects were cultured in maltose-limited retentostat cultures. The secondary-metabolite profile of the wild-type strain defined flavasperone, aurasperone B, tensidol B, and two so far uncharacterized compounds as associated with conidium formation, while fumonisins B2, B4, and B6were characteristic of early response to nutrient limitation by the vegetative mycelium. The developmental mutants responded differently to the severe substrate limitation, which resulted in distinct profiles of growth and product formation.fwnAencodes the polyketide synthase responsible for melanin biosynthesis during aerial differentiation, and we show that conidial melanin synthesis in submerged retentostat cultures and aurasperone B production arefwnAdependent. Thescl-1andscl-2strains are two UV mutants generated in the ΔfwnAbackground that displayed reduced asexual conidiation and formed sclerotium-like structures on agar plates. The reduced conidiation phenotypes of thescl-1andscl-2strains are reflected in the retentostat cultivation and are accompanied by elimination or severely reduced accumulation of secondary metabolites and distinctly enhanced accumulation of extracellular protein. This investigation shows that submerged conidiation and product formation of a mitosporic fungus cultured at low specific growth rates can be fundamentally affected by interfering with the genetic program for differentiation of aerial hyphae, opening new perspectives for tailoring industrial performance.

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Synergistic effects of multiple enzymes from industrial Aspergillus niger strain O1 on starch saccharification

Biotechnology for Biofuels ◽

10.1186/s13068-021-02074-x ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Wenzhu Guo ◽

Jianhua Yang ◽

Tianchen Huang ◽

Dandan Liu ◽

Qian Liu ◽

...

Keyword(s):

Aspergillus Niger ◽

Synergistic Effects ◽

Glycoside Hydrolases ◽

Cell Factory ◽

Microbial Cell Factory ◽

Fermentation Products ◽

Glucoamylase Activity ◽

Starch Saccharification

Abstract Background Starch is one of the most important renewable polysaccharides in nature for production of bio-ethanol. The starch saccharification step facilitates the depolymerization of starch to yield glucose for biofuels production. The filamentous fungus Aspergillus niger (A. niger) is the most used microbial cell factory for production of the commercial glucoamylase. However, the role of each component in glucoamylases cocktail of A. niger O1 for starch saccharification remains unclear except glucoamylase. Results In this study, we identified the key enzymes contributing to the starch saccharification process are glucoamylase, α-amylase and acid α-amylase out of 29 glycoside hydrolases from the 6-day fermentation products of A. niger O1. Through the synergistic study of the multienzymes for the starch saccharification in vitro, we found that increasing the amount of α-amylase by 5-10 times enhanced the efficiency of starch saccharification by 14.2-23.2%. Overexpression of acid α-amylase in strain O1 in vivo increased the total glucoamylase activity of O1 cultures by 15.0%. Conclusions Our study clarifies the synergistic effects among the components of glucoamylases cocktail, and provides an effective approach to optimize the profile of saccharifying enzymes of strain O1 for improving the total glucoamylase activity.

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Changes in activity of certain enzymes of the tricarboxylic acid cycle and the glyoxylate cycle during the initiation of conidiation of Aspergillus niger

Canadian Journal of Microbiology ◽

10.1139/m69-218 ◽

1969 ◽

Vol 15 (10) ◽

pp. 1207-1212 ◽

Cited By ~ 21

Author(s):

J. C. Galbraith ◽

J. E. Smith

Keyword(s):

Life Cycle ◽

Aspergillus Niger ◽

Isocitrate Lyase ◽

Tricarboxylic Acid Cycle ◽

Glyoxylate Cycle ◽

Tca Cycle ◽

Tricarboxylic Acid ◽

Acid Cycle ◽

Glycine Synthesis ◽

The Glyoxylate Cycle

The activities of certain enzymes of the tricarboxylic acid (TCA) cycle and the glyoxylate cycle (GLC) varied during growth of Aspergillus niger as a function of the stage of the life cycle and of the growth medium. Isocitrate dehydrogenase (carboxylating) and isocitrate lyase each showed a marked increase in activity prior to sporulation. There were no similar increases in vegetative cultures. It is proposed that isocitrate lyase is functional in glycine synthesis and that a source of glyoxylate may be indispensable to the expression of sporulation.

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A new group of exo-acting family 28 glycoside hydrolases of Aspergillus niger that are involved in pectin degradation

Biochemical Journal ◽

10.1042/bj20060703 ◽

2006 ◽

Vol 400 (1) ◽

pp. 43-52 ◽

Cited By ~ 42

Author(s):

Elena S. Martens-Uzunova ◽

Joris S. Zandleven ◽

Jaques A. E. Benen ◽

Hanem Awad ◽

Harrie J. Kools ◽

...

Keyword(s):

Aspergillus Niger ◽

Genomic Sequence ◽

Glycoside Hydrolases ◽

Pectin Degradation ◽

Entire Genome ◽

Gene Group ◽

Degrading Enzymes ◽

New Genes ◽

New Gene ◽

Biochemical Identification

The fungus Aspergillus niger is an industrial producer of pectin-degrading enzymes. The recent solving of the genomic sequence of A. niger allowed an inventory of the entire genome of the fungus for potential carbohydrate-degrading enzymes. By applying bioinformatics tools, 12 new genes, putatively encoding family 28 glycoside hydrolases, were identified. Seven of the newly discovered genes form a new gene group, which we show to encode exoacting pectinolytic glycoside hydrolases. This group includes four exo-polygalacturonan hydrolases (PGAX, PGXA, PGXB and PGXC) and three putative exo-rhamnogalacturonan hydrolases (RGXA, RGXB and RGXC). Biochemical identification using polygalacturonic acid and xylogalacturonan as substrates demonstrated that indeed PGXB and PGXC act as exo-polygalacturonases, whereas PGXA acts as an exo-xylogalacturonan hydrolase. The expression levels of all 21 genes were assessed by microarray analysis. The results from the present study demonstrate that exo-acting glycoside hydrolases play a prominent role in pectin degradation.

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Ultrastructural analysis of “Sensory” surface nerve endings and “putative” neurotransmitter sites in Schistosoma mansoni Miracidia

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100156791 ◽

1989 ◽

Vol 47 ◽

pp. 962-963

Author(s):

Betty Ruth Jones ◽

Steve Chi-Tang Pan

Keyword(s):

Nervous System ◽

Life Cycle ◽

Schistosoma Mansoni ◽

Snail Host ◽

Complex Life Cycle ◽

Rational Approach ◽

Effective Control ◽

The Social ◽

Social And Economic Development ◽

Basic Biology

INTRODUCTION: Schistosomiasis has been described as “one of the most devastating diseases of mankind, second only to malaria in its deleterious effects on the social and economic development of populations in many warm areas of the world.” The disease is worldwide and is probably spreading faster and becoming more intense than the overall research efforts designed to provide the basis for countering it. Moreover, there are indications that the development of water resources and the demands for increasing cultivation and food in developing countries may prevent adequate control of the disease and thus the number of infections are increasing.Our knowledge of the basic biology of the parasites causing the disease is far from adequate. Such knowledge is essential if we are to develop a rational approach to the effective control of human schistosomiasis. The miracidium is the first infective stage in the complex life cycle of schistosomes. The future of the entire life cycle depends on the capacity and ability of this organism to locate and enter a suitable snail host for further development, Little is known about the nervous system of the miracidium of Schistosoma mansoni and of other trematodes. Studies indicate that miracidia contain a well developed and complex nervous system that may aid the larvae in locating and entering a susceptible snail host (Wilson, 1970; Brooker, 1972; Chernin, 1974; Pan, 1980; Mehlhorn, 1988; and Jones, 1987-1988).

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A freeze-fracture-etched study of the physarum polycephalum plasma membrane during early formation of the macroplasmodial stage

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100147570 ◽

1993 ◽

Vol 51 ◽

pp. 346-347

Author(s):

Randolph W. Taylor ◽

Henrie Treadwell

Keyword(s):

Plasma Membrane ◽

Life Cycle ◽

Growth Phase ◽

Filter Paper ◽

Physarum Polycephalum ◽

Freeze Fracture ◽

Petri Dish ◽

Wire Screen ◽

Wide Mouth ◽

Sterile Filter

The plasma membrane of the Slime Mold, Physarum polycephalum, process unique morphological distinctions at different stages of the life cycle. Investigations of the plasma membrane of P. polycephalum, particularly, the arrangements of the intramembranous particles has provided useful information concerning possible changes occurring in higher organisms. In this report Freeze-fracture-etched techniques were used to investigate 3 hours post-fusion of the macroplasmodia stage of the P. polycephalum plasma membrane.Microplasmodia of Physarum polycephalum (M3C), axenically maintained, were collected in mid-expotential growth phase by centrifugation. Aliquots of microplasmodia were spread in 3 cm circles with a wide mouth pipette onto sterile filter paper which was supported on a wire screen contained in a petri dish. The cells were starved for 2 hrs at 24°C. After starvation, the cells were feed semidefined medium supplemented with hemin and incubated at 24°C. Three hours after incubation, samples were collected randomly from the petri plates, placed in plancettes and frozen with a propane-nitrogen jet freezer.

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