Novel optimization strategy for tannase production through a modified solid-state fermentation system

Abstract

BackgroundHigh amounts of insoluble substrates exist in the traditional solid-state fermentation (SSF) system. The presence of these substrates complicates the determination of microbial biomass. Thus, enzyme activity is used as the sole index for the optimization of the traditional SSF system, and the relationship between microbial growth and enzyme synthesis is always ignored. This study was conducted to address this deficiency. All soluble nutrients from tea stalk were extracted using water. The aqueous extract was then mixed with polyurethane sponge to establish a modified SSF system, which was then used to conduct tannase production. With this system, biomass, enzyme activity, and enzyme productivity could be measured rationally and accurately. Thus, the association between biomass and enzyme activity could be easily identified, and the shortcomings of traditional SSF could be addressed.ResultsDifferent carbon and nitrogen sources exerted different effects on microbial growth and enzyme production. Single-factor experiments showed that glucose and yeast extract greatly improved microbial biomass accumulation and that tannin and (NH4)2SO4 efficiently promoted enzyme productivity. Then, these four factors were optimized through response surface methodology. Tannase activity reached 19.22 U/gds when the added amounts of tannin, glucose, (NH4)2SO4, and yeast extract were 7.49, 8.11, 9.26, and 2.25%, respectively. Tannase activity under the optimized process conditions was 6.36 times higher than that under the initial process conditions. The optimized parameters were directly applied to the traditional tea stalk SSF system. Tannase activity reached 245 U/gds, which is 2.9 times higher than our previously reported value.ConclusionsIn this study, a modified SSF system was established to address the shortcomings of the traditional SSF system. Analysis revealed that enzymatic activity and microbial biomass are closely related, and different carbon and nitrogen sources have different effects on microbial growth and enzyme production. The maximal tannase activity was obtained under the optimal combination of nutrient sources that enhances cell growth and tannase accumulation. Moreover, tannase production through the traditional tea stalk SSF was markedly improved when the optimized parameters were applied. This work provides an innovative approach to bioproduction research through SSF.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1093-0) contains supplementary material, which is available to authorized users.

Implementation of Different Fermentation Techniques for Induction of Tannase and Gallic Acid Using Agro-residues Substrates

“…SSF can be used in case of nearly or completely absence or near absent of free liquid when using a solid substrate as raw materials. The advantages of this method are the use low cost raw materials, little energy consumption and small bioreactor dimensions because of the concentrated media (Couto &Toca-Herrera, 2007 andWu et al, 2018).…”

RETRACTED ARTICLE: Substrates specificity of tannase from Streptomyces sviceus and Lactobacillus plantarum

“…At present, the production of secreted tannase for industrial applications involves the utility of either crude or semi-purified enzyme prepared from submerged or solid-state cultures of Aspergillus niger or Aspergillus oryzae fermented in the presence of tannic acid (Aguilar et al 2007 ; Varadharajan et al 2017 ; Wu et al 2018 ). However, low yield and purity, batch variability and a poor understanding of catalytic mechanism of tannase have limited its utility.…”

Corn (Zea Mays) Leaves as Cost-Effective Substrate for Enhanced Tannase Production Under Solid State Fermentation: Optimization and Characterization

“…Kumar et al (2007) reported the decrease in tannase production by use of complex nitrogen source, yeast extract. Yeast extract as organic nitrogen source is rarely chosen in traditional SSF due to its very slight effect on the synthesis of enzyme as reported by Wu et al (2018).…”

“…Selvaraj and Vytla (2018) determined 1% tannic acid as medium component using CCD for optimal tannase synthesis by B. gottheilii M2S2. RSM optimized components of 7.49% tannin, 8.11% glucose, 2.25% yeast extract and 9.26% (NH 4 ) 2 SO 4 were obtained by Wu et al (2018) for highest tannase productivity from Aspergillus tubingensis CICC 2651 using tea stalk under SSF. So, the requirement of medium composition and their concentrations could vary depending on microorganism or substrate used.…”