Liquid Surface Fermentation Research Articles

Production and Characterization of Natural Tannin-Degrading Aspergillus strains

Among the different types of agrowastes, tannin biomass also contributes to significant amount. The tannin rich biomass can be exploited as the most economic substrate for the production of industrially important enzyme Tannase. Tannases are hydrolases which find applications in different industries such as leather, food, feed, beverage and pharmaceutical industry. Tannases are gaining importance as industrially-important biocatalyst. The present study focuses on the isolation of natural tannin degrading fungal strains including their characterization. Among the fifty fungal cultures isolated from soil samples, eleven tannase producing isolates were selected by qualitative screening. The selected isolates were cultivated by liquid surface fermentation for quantitative estimation of extracellular tannase activity. On the basis of quantitative screening, two isolates Aspergillus niger and Aspergillus flavus were identified as efficient tannase producers. To study natural tannin degradation efficiency of the isolates, different tannin rich agro-residues were tested as carbon source in the production medium for tannase production as well as substrate for the enzyme. Both isolates utilized natural tannins appreciably, producing significant tannase yield. Gauva leaves and ber leaves proved to be the best carbon source for Aspergillus niger and Aspergillus flavus respectively. The optimum incubation period for maximum tannin utilization was found to be 72 hrs for Aspergillus niger and 96 hrs for Aspergillus flavus. In conclusion, both fungal isolates exhibited potential for tannin biomass utilization and conversion to various valuable industrial products.

Citric Acid Production by Aspergillus Niger through Submerged and Solid-State Fermentation: An Overview

Currently, citric acid is produce through microbial fermentation using various microorganisms in three different techniques, viz. submerged culture fermentation (SmF), solid-state fermentation (SSF) and liquid surface fermentation (LSF). Majority of the present commercial production of citric acid is through submerged culture fermentation by using A. niger on by-product of sugar industry as substrate. However, lately, exploitation of solid state fermentation has demonstrated some prospective in becoming a substitute to submerged fermentation for the commercial production of citric acid. In view of finding an alternative fermentation technique for citric acid production which is more effective, fuel-efficient, labour-saving and economical than the existing ones, this review discusses a comparative account of solid-state fermentation and submerged fermentation.

Optimisation of extracellular tannase production from Paecilomyces variotii

The tannase production by Paecilomyces variotii was confirmed by high performance thin layer chromatography (HPTLC), and substrate specificity of the tannase was determined by zymogram analysis in sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS–PAGE). A clear band of activity observed after electrophoresis of culture filtrate in non-denaturing gels indicated the production of extracellular tannase by P. varoitii. HPTLC analysis revealed that gallic acid was the enzymatic degradation product of tannic acid during the fermentation process. The optimum condition for tannase production was at 72 h of incubation in shaking condition and addition of 1.5% tannic acid, 1% glucose and 0.2% sodium nitrate at temperature of 35°C and pH of 5–7. The production of extracellular tannase from Paecilomyces variotii was investigated under optimized conditions in solid-state fermentation (SSF), submerged fermentation (SmF) and liquid surface fermentation (LSF) processes. The maximum extracellular tannase production was obtained within 60 h of incubation under SSF followed by SmF and LSF.

Effect of fermentation system on the production and properties of tannase of Aspergillus niger van Tieghem MTCC 2425

The tannase-producing efficiency of liquid-surface fermentation (LSF) and solid-state fermentation (SSF) vis-à-vis submerged fermentation (SmF) was investigated in a strain of Aspergillus niger, besides finding out if there was a change in the activity pattern of tannase in these fermentation processes. The studies on the physicochemical properties were confined to intracellular tannase as only this form of enzyme was produced by A. niger in all three fermentation processes. In LSF and SmF, the maximum production of tannase was observed by 120 h, whereas in SSF its activity peaked at 96 h of growth. SSF had the maximum efficiency of enzyme production. Tannase produced by the SmF, LSF and SSF processes had similar properties except that the one produced during SSF had a broader pH stability of 4.5-6.5 and thermostability of 20 degrees-60 degrees C.

In vitro efficacies of phosphorolytic enzymes synthesized in mycelial cells of Aspergillus niger AbZ4 grown by a liquid surface fermentation.

Activities of phytase, a pH 6.0 optimum nonspecific phosphomonoesterase and phosphodiesterase assayed toward bis(p-nitrophenyl)phosphate (phosphodiesterase I) and against p-nitrophenylphosphorylcholine (phosphodiesterase II), were partially purified from mycelial extracts of Aspergillus niger AbZ4 cultivated on a molasses medium by a liquid surface fermentation method. After elimination of phosphate from the medium, 7.3- and 3.5-fold enhancements in specific activities of phytase and phosphodiesterase II were observed. Efficacies of mycelial protein fractions in dephosphorylating a wheat-based broiler feed were determined in vitro according to a procedure that simulated digestion in the intestinal tract of poultry. The addition of 0.052 mg of protein from fractions, each of which was high in either pH 6.0 optimum phosphomonoesterase, phosphodiesterase I, phosphodiesterase II, or phytase per gram of a feed sample resulted in the enhancement of phosphorus release by 10, 11, 27, and 88%, respectively. In the presence of an excess of commercial phytase, the addition of the mycelial fraction high in phytase increased the dephosphorylation rate by 56%. The fraction high in phosphodiesterase II enhanced feed dephosphorylation by 8% in the presence of an excess of commercial phytase and commercial acid phosphatase.

GIBBERELLIC ACID PRODUCTION BY FUNGI

Fifteen fungal cultures including one type strain. Gibberella fujikuroi were screened for gibberellic acid production using Liquid Surface Fermentation (LSF) and Submerged Fermentation (SmF) techniques. G. fujikuroi produced the highest quantity of GA, followed by Botryodiplodia theobromae in both the fermentation processes. In general gibberellic acid production was more in SmF when compared to LSF.

Preliminary Studies on the Production of High and Low Viscosity Dextran by Leuconostoc spp.

Isolates of Leuconostoc mesenteroides NRRL B-512 (F) and Leuconostoc dextranicum FPW-10 grew well and produced good yields of dextran from sucrose in unaerated or liquid surface fermentation and in shake flask culture which contained extract of wheat bran and dibasic potassium phosphate as nutrients. High temperature (20–26°C), unaerated fermentation of 10 and 20% sucrose (w/v) media by L. dextranicum FPW-10 resulted in viscosities of 80 and 430 cP, respectively. The corresponding weights of crude dextran obtained for every 100 g sucrose were 45 and 32·5 g. Enhancement of viscosities to 420 and 1280 cP occurred in corresponding shake flask cultures but without much change in yields. High temperature fermentations were completed in 24 h. The fermentation of 10 and 20% sucrose media under prolonged (72 h) unaerated low temperature (10–13°C) resulted in an increase in broth viscosities to 2300 and 2800 cP and yields to 50 g each, respectively. The reference L. mesenteroides B-512 culture performed similarly under these mentioned conditions. Factors such as concentration of wheat bran extract, inoculum size and fermentation period influenced the viscosity and yield of dextran in fermented broths.

Preliminary studies on the production of high and low viscosity dextran by Leuconostoc spp.

Isolates of Leuconostoc mesenteroides NRRL B-512 (F) and Leuconostoc dextranicum FPW-10 grew well and produced good yields of dextran from sucrose in unaerated or liquid surface fermentation and in shake flask culture which contained extract of wheat bran and dibasic potassium phosphate as nutrients. High temperature (20–26°C), unaerated fermentation of 10 and 20% sucrose (w/v) media by L. dextranicum FPW-10 resulted in viscosities of 80 and 430 cP, respectively. The corresponding weights of crude dextran obtained for every 100 g sucrose were 45 and 32·5 g. Enhancement of viscosities to 420 and 1280 cP occurred in corresponding shake flask cultures but without much change in yields. High temperature fermentations were completed in 24 h. The fermentation of 10 and 20% sucrose media under prolonged (72 h) unaerated low temperature (10–13°C) resulted in an increase in broth viscosities to 2300 and 2800 cP and yields to 50 g each, respectively. The reference L. mesenteroides B-512 culture performed similarly under these mentioned conditions. Factors such as concentration of wheat bran extract, inoculum size and fermentation period influenced the viscosity and yield of dextran in fermented broths.

Organic acid production by immobilized filamentous fungi

The filamentous fungi may be defined as microscopic eukaryotic organisms producing fine filamentous growth on various substrates (Fassatiova, 1986). In nature they are involved in the production of humus and many live in the soil. On the other hand filamentous fungi are used in fermentation technology. A variety of metabolites of industrial importance such as enzymes, vitamins, antibiotics, organic acids, hormones, steroids, can be produced by them. Two processes are used in organic acid production in which special strains of filamentous fungi are employed: liquid surface fermentation, in which mycelium floats on the surface of a feed solution; and the submerged process in which the mycelium grows throughout a solution in a deep tank. Current fermentation processes employing fungal cells require large amounts of energy and yields are usually low .