Development of an RP-UHPLC-PDA method for quantification of free gossypol in cottonseed cake and fungal-treated cottonseed cake

An Enzymatic and Proteomic Analysis of Panus lecomtei during Biodegradation of Gossypol in Cottonseed

Cotton is an important plant-based protein. Cottonseed cake, a byproduct of the biodiesel industry, offers potential in animal supplementation, although the presence of the antinutritional sesquiterpenoid gossypol limits utilization. The macrofungus Panus lecomtei offers potential in detoxification of antinutritional factors. Through an enzymatic and proteomic analysis of P. lecomtei strain BRM044603, grown on crushed whole cottonseed contrasting in the presence of free gossypol (FG), this study investigated FG biodegradation over a 15-day cultivation period. Fungal growth reduced FG to levels at 100 μg/g, with a complex adaptive response observed, involving primary metabolism and activation of oxidative enzymes for metabolism of xenobiotics. Increasing activity of secreted laccases correlated with a reduction in FG, with enzyme fractions degrading synthetic gossypol to trace levels. A total of 143 and 49 differentially abundant proteins were observed across the two contrasting growth conditions after 6 and 12 days of cultivation, respectively, revealing a dynamic protein profile during FG degradation, initially related to constitutive metabolism, then later associated with responses to oxidative stress. The findings advance our understanding of the mechanisms involved in gossypol degradation and highlight the potential of P. lecomtei BRM044603 in cotton waste biotreatment, relevant for animal supplementation, sustainable resource utilization, and bioremediation.

Biodegradation of Gossypol by Aspergillus terreus-YJ01

Gossypol, generally found in the roots, stems, leaves, and, especially, the seeds of cotton plants, is highly toxic to animals and humans, which inhibits the use of cotton stalks as a feed resource. Here, a promising fungal strain for biodegrading gossypol was successfully isolated from the soil of cotton stalk piles in Xinjiang Province, China, and identified as Aspergillus terreus-YJ01 with the analysis of ITS. Initial gossypol of 250 mg·L-1 could be removed by 97% within 96 h by YJ01, and initial gossypol of 150 mg·L-1 could also be catalyzed by 98% or 99% within 36 h by the intracellular or extracellular crude enzymes of YJ01. Sucrose and sodium nitrate were found to be the optimal carbon and nitrogen sources for the growth of YJ01, and the optimal initial pH and inoculum size for the growth of YJ01 were 6.0 and 1%, respectively. To further elucidate the mechanisms underlying gossypol biodegradation by YJ01, the draft genome of YJ01 was sequenced using Illumina HiSeq, which is 31,566,870 bp in length with a GC content of 52.27% and a total of 9737 genes. Eight genes and enzymes were predicted to be involved in gossypol biodegradation. Among them, phosphoglycerate kinase, citrate synthase, and other enzymes are related to the energy supply process. With sufficient energy, β-1, 4-endo-xylanase may achieve the purpose of biodegrading gossypol. The findings of this study provide valuable insights into both the basic research and the application of A. terreus-YJ01 in the biodegradation of gossypol in cotton stalks.

Cottonseed Meal Protein Isolate as a New Source of Alternative Proteins: A Proteomics Perspective

Cottonseed meal (CSM) is a good source of dietary proteins but is unsuitable for human consumption due to its gossypol content. To unlock its potential, we developed a protein extraction process with a gossypol removal treatment to generate CSM protein isolate (CSMPI) with ultra-low gossypol content. This process successfully reduced the free and total gossypol content to 4.8 ppm and 147.2 ppm, respectively, far below the US FDA limit. In addition, the functional characterisation of CSMPI revealed a better oil absorption capacity and water solubility than pea protein isolate. Proteome profiling showed that the treatment improved protein identification, while SDS-PAGE analysis indicated that the treatment did not induce protein degradation. Amino acid analysis revealed that post-treated CSMPI was rich in branched-chain amino acids (BCAAs). Mass spectrometry analysis of various protein fractions obtained from an in vitro digestibility assay helped to establish the digestibility profile of CSM proteins. Several potential allergens in CSMPI were also found using allergenic prediction software, but further evaluation based on their digestibility profiles and literature reviews suggests that the likelihood of CSMPI allergenicity remains low. Overall, our results help to navigate and direct the application of CSMPIs as alternative proteins toward nutritive human food application.

Bioactives and Extracellular Enzymes Obtained from Fermented Macrofungi Cultivated in Cotton and Jatropha Seed Cakes

This work focused on obtaining fermented oil cake (cotton or Jatropha) via macrofungi growth with potential characteristics for animal feed formulations, such as the presence of extracellular enzymes, bioactive (ergosterol and antioxidants), and detoxification of antinutritional compounds. The concentration of phorbol esters was reduced by four macrofungi in Jatropha seed cake (JSC) to non-toxic levels. At least two macrofungi efficiently degraded free gossypol in cottonseed cake (CSC). Fermentation with Coriolopsis sp. INPA1646 and Tyromyces sp. INPA1696 resulted in increased ergosterol concentrations, antioxidant activity reduction, and high activity of laccases and proteases. Bromatological analysis indicated high crude protein concentrations, with partial solubilization by fungal proteases. Fermented products from Coriolopsis sp. and Tyromyces sp. in JSC or CSC can be considered important biological inputs for monogastric and polygastric animal feed.