The potential of two zygomycetes fungi, Mucor indicus and Rhizopus oryzae, in assimilating citrus waste free sugars (CWFS) and producing fungal chitosan, oil, and protein as well as ethanol was investigated. Extraction of free sugars from citrus waste can reduce its environmental impact by decreasing the possibility of wild microorganisms growth and formation of bad odors, a typical problem facing the citrus industries. A total sugar concentration of 25.1 g/L was obtained by water extraction of citrus waste at room temperature, used for fungal cultivation in shake flasks and airlift bioreactor with no additional nutrients. In shake flasks cultivations, the fungi were only able to assimilate glucose, while fructose remained almost intact. In contrast, the cultivation of M. indicus and R. oryzae in the four-liter airlift bioreactor resulted in the consumption of almost all sugars and production of 250 and 280 g fungal biomass per kg of consumed sugar, respectively. These biomasses correspondingly contained 40% and 51% protein and 9.8% and 4.4% oil. Furthermore, the fungal cell walls, obtained after removing the alkali soluble fraction of the fungi, contained 0.61 and 0.69 g chitin and chitosan per g of cell wall for M. indicus and R. oryzae, respectively. Moreover, the maximum ethanol yield of 36% and 18% was obtained from M. indicus and R. oryzae, respectively. Furthermore, that M. indicus grew as clump mycelia in the airlift bioreactor, while R. oryzae formed spherical suspended pellets, is a promising feature towards industrialization of the process.

The present research describes an integral strategy for valorisation of fruit and vegetable discards (FVd) in feeding application, using solid-state fermentation (SSF) and submerged fermentation (SmF), for both solid and liquid fractions obtained during these by-products handle and processing, using a strain of Rhizopus sp. After SSF, fermented biomass had 1.9 times higher protein content (up to 20.2 ± 1.7% DM) than the original mass and an improved amino acid (AA) profile (45.7 ± 1.8% essential AAs). Fatty acid (FA) profile was also modified during fermentation process, with higher monounsaturated (MUFA) and lower polyunsaturated fatty acid (PUFA) percentage in the final product compared with initial substrate. Phenolic compound concentration was double in final biomass than in initial substrate (up to 8.9 ± 1.5 mg GAE/g DM) and fermented product had higher antioxidant activity (DPPH reduction of 81.3 ± 7.7% and TEAC of 3.6 ± 0.3 mg/g DM). Compared with previously reported results, fruit complementation with vegetables increased the available nitrogen and resulted in higher biomass production. The fruit and vegetable leachate (FVL) obtained by centrifugation was treated by SmF and led, per liter of substrate, to 10.6 ± 1.4 g of fungal biomass and 3.3 g protein after 7 days of fermentation. Obtained fungal biomass was rich in PUFAs (27.1 ± 7.2% of total FA) and had an AA profile comparable to soybean meal, with 45.3 ± 1.5% of essential amino acids (EAA). In conclusion, results demonstrate that combined solid and liquid fermentation is a successful strategy for FVd valorisation to produce valuable alternative feed ingredient due to their high protein and the well-balanced lipid content and amino acid profile.

A co-fermentation process involving Yarrowia lipolytica and Trichoderma reesei was studied, using distillers grains (DGS) as feedstocks for erythritol production. DGS can be effectively hydrolyzed by cellulase in the single-strain culture of T. reesei. One-pot solid state fermentation for erythritol production was then established by co-cultivating Y. lipolytica M53-S with the 12 h delay inoculated T. reesei Rut C-30, in which efficient saccharification of DGS and improved production of erythritol were simultaneously achieved. The 10:1 inoculation proportion of Y. lipolytica and T. reesei contributed to the maximum erythritol production of 267.1 mg/gds under the optimal conditions including initial moisture of 55%, pH of 5.0, NaCl addition of 0.02 g/gds and DGS mass of 200 g in 144 h co-cultivation. Being compared with the attempts to produce erythritol from other raw materials, the one-pot SSF with DGS is proposed to be a potential strategy for efficient and economical erythritol production.

The drumstick tree is a fast-growing multipurpose tree with a large biomass and high nutritional value. However, it has rarely been exploited as a protein source. This study investigated solid-state fermentation induced by , and to obtain high-quality protein feed from drumstick leaf flour. The results showed that fermentation induced significant changes in the nutritional composition of drumstick leaf flour. The concentrations of crude protein, small peptides and amino acids increased significantly after fermentation. The protein profile was also affected by the fermentation process. Macromolecular proteins in drumstick leaf flour were degraded, whereas other high molecular weight proteins were increased. However, the concentrations of crude fat, fiber, total sugar and reducing sugar were decreased, as were the anti-nutritional factors tannins, phytic acid and glucosinolates. After 24 h fermentation, the concentrations of total phenolics and flavonoids were increased. The antioxidant capacity was also significantly enhanced.

BACKGROUND:To date, fungus-assisted pretreatment of agricultural residue has not become the preferred method to produce protein-enriched and ruminally digestible animal feed because of low time efficiency of fungal delignification and protein production, i.e. the long solid-state fermentation period, and because of laccase as a potential inhibitor of cellulose activity. In this study, response surface methodology was employed to optimize the parameters in the process of producing nutritious animal feed from wheat straw with Inonotus obliquus pretreatment. RESULTS:The mineral salt solution containing (w/v) (NH ) SO 1%, MgSO ·7H O 0.03%, KH PO 0.011%, Tween-80 0.4%, and corn starch 10% with pH of 7.4 was optimized. Inonotus obliquus rapidly and completely colonized on wheat straw with an ergosterol content of 280 μg g dry matter, consuming 45% of lignin after 15 days of fermentation, producing maximums of lignin peroxidase (1729 IU g ), manganese peroxidase (610 IU g ) and laccase (98 IU g ) on days 5, 15, and 25, respectively. The crude protein (102.4 g kg ) of 15-day fermented wheat straw increased by ~132%. After hydrolysis, the essential protein-bound amino acids (15.3 g kg ) increased by ~47%, within which Met and Lys measured ~1070% and ~60% higher. The treatment with I. obliquus also improved the in vitro gas production after 72 h (IVGP ) of wheat straw to 178.8 mL g organic matter (~43% increase). CONCLUSION:For the first time, we found that I. obliquus is an effective white rot fungus turning wheat straw into ruminally digestible animal feed without laccase inhibitor.

BACKGROUND:Cottonseed meal (CSM) is the main by-product of the cottonseed oil extraction process with high protein content, which is an important protein source for feed industry. However, CSM contains free gossypol (FG), a toxic substance that is detrimental to animal health and greatly limits its application. Microbial fermentation is currently considered to be one of the most effective methods to reduce FG and other anti-nutritional factors in CSM. Previously, yeast and bacteria species are used for degradation of FG in CSM, but showing less detoxification efficiency. Bacillus coagulans combines the properties of both lactic acid bacteria and Bacillus, producing both lactic acid and spores, and is considered a potential probiotic. In this study, we aimed to evaluate and optimize the effect of the solid-state fermentation process using a Bacillus coagulans to gossypol removal contained cottonseed meal. RESULTS:36 B. coagulans strains were isolated and found to have the ability to remove free gossypol. Through the evaluation of strains and optimization of fermentation conditions including fermentation temperature, ratio of material to water, inoculation amount, fermentation time and pH, we have established a solid-state fermentation process using a Bacillus coagulans strain S17 on CSM substrate with 1:1 of the material-to-water ratio, 15% (v/w) seed inoculation, 2% expanded corn flour, 1% bran, and 0.3%-0.8% metal irons at 40 °C for 52 h. After fermentation, the FG content in CSM was reduced from 923.80 to 167.90 mg/kg with 81.83% detoxification efficiency. Meanwhile, the crude protein content in CSM increased from 47.98 to 52.82%, and importantly, the spore concentration of strain S17 reached 1.68 × 10 CFU/g dry material. CONCLUSION:The study showed that B. coagulans have the potential strong ability to degrade free gossypol through cottonseed meal fermentation. This study presents a feasible process for improving the resource utilization rate and nutritional value of CSM via solid-state fermentation through B. coagulans S17.

Chrysanthemum waste (CW) is an agricultural and industrial by-product produced during chrysanthemum harvesting, drying, preservation, and deep processing. Although it is nutritious, most CW is discarded, wasting resources and contributing to serious environmental problems. This work explored a solid-state fermentation (SSF) strategy to improve CW quality for use as an alternative feed ingredient. Orthogonal experiment showed that the optimal conditions for fermented chrysanthemum waste (FCW) were: CW to cornmeal mass ratio of 9:1, Pediococcus cellaris + Candida tropicalis + Bacillus amyloliquefaciens proportions of 2:2:1, inoculation amount of 6%, and fermentation time of 10 d. Compared with the control group, FCW significantly increased the contents of crude protein, ether extract, crude fiber, acid detergent fiber, neutral detergent fiber, ash, calcium, phosphorus, and total flavonoids (p < 0.01), and significantly decreased pH and saponin content (p < 0.01). SSF improved the free and hydrolyzed amino acid profiles of FCW, increased the content of flavor amino acids, and improved the amino acid composition of FCW protein. Overall, SSF improved CW nutritional quality. FCW shows potential use as a feed ingredient, and SSF helps reduce the waste of chrysanthemum processing.

The use of waste stream residues as feedstock for material production simultaneously helps reduce dependence on fossil-based resources and to shift toward a circular economy. This study explores the conversion of food waste into valuable chemicals, namely, bio-pigments. Here, a simulated food waste feedstock was converted into pigments via solid-state fermentation with the filamentous fungus Talaromyces albobiverticillius (NRRL 2120). Pigments including monascorubrin, rubropunctatin, and 7-(2-hydroxyethyl)-monascorubramine were identified as products of the fermentation via ultra-performance liquid chromatography coupled with quadrupole-time-of-flight electrospray ionization mass spectrometry. Pigments were obtained at concentrations of 32.5, 20.9, and 22.4 AU/gram dry substrate for pigments absorbing at 400, 475, and 500 nm, respectively. Pigment production was further enhanced by co-culturing T. albobiverticillius with Trichoderma reesei (NRRL 3652), and ultimately yielded 63.8, 35.6, and 43.6 AU/gds at the same respective wavelengths. This represents the highest reported production of pigments via solid-state fermentation of a non-supplemented waste stream feedstock. KEY POINTS: • Simulated food waste underwent solid-state fermentation via filamentous fungi. • Bio-pigments were obtained from fermentation of the simulated food waste. • Co-culturing multiple fungal species substantially improved pigment production.