Fruit wastes can be imperative to elevate economical biomass to biofuels production process at pilot scale. Because of the renewable features, huge availability, having low lignin content organic nature and low cost; these wastes can be of much interest for cellulase enzyme production. This review provides recent advances on the fungal cellulase production using fruit wastes as a potential substrate. Also, the availability of fruit wastes, generation and processing data and their potential applications for cellulase enzyme production have been discussed. Several aspects, including cellulase and its function, solid-state fermentation, process parameters, microbial source, and the application of enzyme in biofuels industries have also been discussed. Further, emphasis has been made on various bottlenecks and feasible approaches such as use of nanomaterials, co-culture, molecular techniques, genetic engineering, and cost economy analysis to develop a low-cost based comprehensive technology for viable production of cellulase and its application in biofuels production technology.

Mycoremediation of unsterilized PCDD/F-contaminated field soil was successfully demonstrated by solid-state fermentation coupled with Pleurotus pulmonarius utilizing a patented incubation approach. The experiments were carried out in four setups with two as controls. The contaminated soil was homogenously mixed with solid inocula, 1:0.5 dry w/w, resulting in an initial concentration of 4432 ± 623 ng WHO-TEQ kg⁻¹. After a 30-day incubation under controlled conditions, the overall removal (approx. 60%) was non-specific. The removal was attributed to degradation by extracellular ligninolytic enzymes and uptake into the fruiting tissue (~110 ng WHO-TEQ kg⁻¹ of mushroom). Furthermore, less recalcitrant chlorinated metabolites were found, implying ether bond cleavage and dechlorination happened during the mycoremediation. These metabolites resulted from the complex interaction between P. pulmonarius and the indigenous microbes from the unsterilized soil. This study provides a new step toward scaling up this mycoremediation technique to treat unsterilized PCDD/F-contaminated field soil.

This study presents a comprehensive investigation into the production of amylase, a crucial enzyme with wide-ranging industrial applications, using locally sourced substrates from Kachchh, Gujarat. The research employed the Bacillus licheniformis strain and substrates such as coconut, rice husk, wheat bran, paddy straw, and maize straw. The study found paddy straw to be the most promising substrate for amylase production. The research also systematically optimized various process parameters for amylase production in Solid-State Fermentation (SSF) using the One Variable at a Time (OVAT) method. These parameters included incubation period, temperature, inoculum level, additional carbon sources, starch concentrations, additional nitrogen sources, initial pH, different mineral salt ions, initial moisture level, and surfactants. The results showed that the optimal conditions for maximum amylase yield were an incubation period of 48 hours, an incubation temperature of 35°C, an inoculum level of 10%, starch as the additional carbon source, a starch concentration of 2.5%, yeast extract as the additional nitrogen source, an initial pH of 7, NaCl as the mineral salt, an initial moisture level of 75%, and Tween 80 as the surfactant. This research provides a reliable and sustainable approach to enzyme production, offering valuable insights for the optimization of the solid-state fermentation process for maximum amylase production.

The presence of synthetic dyes in effluents leads to an environmental imbalance characterized by a decrease in photosynthetic activity and, therefore, a reduction of available oxygen, which affects all living aquatic species. To reduce this problem, a combination adsorption and biodegradation treatment strategy is proposed. In this work, Red 40 dye was adsorbed onto a low-cost waste product, followed by degradation by Trametes versicolor under solid state fermentation conditions. The principal aim of this research was to establish the best fermentation conditions using a kinetic evaluation of both degradation and laccase enzyme activity. The process was scaled-up using a rotating drum bioreactor. The best process conditions were a carbon:nitrogen ratio of 30:1, a moisture percentage of 75%, and an inductor concentration of 0.5 mM; the maximum dye degradation was 96.04%. Under these optimized conditions, the highest enzymatic activity was 8.49 U/gdₘ after 14 days of culture at the flask scale. Using a rotating drum bioreactor, 630 mg of azo dye was degraded after 30 days of culture. Red 40 dye degradation was confirmed using infrared spectroscopy Fourier transform infrared spectrometer and HPLC-MS techniques. The results show that the degradation percentage has a direct relation with laccase activity, and the obtained efficiency in the rotating drum bioreactor confirms the potential of this methodology for implementation at the industrial level.

The use of solid-state fermentation (SFF) of low cost substrates by fungal species to generate organic acid solutions for washing of lead from a contaminated soil was evaluated in this study. SFF filtrates were generated by fermentation of four substrates (corn cobs, apple pomace, rice and hay) with three fungal species (Aspergillus niger NRRL 2001 (A. niger 1), Aspergillus niger ATCC 64065 (A. niger 2), Aspergillus foetidus NRRL 337) at three fermentation times. The concentration and speciation of organic acids of the filtrates was found to be a function of the substrate type, the fungal species and the fermentation time. Fermentation of rice resulted in the highest concentrations of citric acid while fermentation of corn cobs, apple pomace and hay tended to generate oxalic acid with an increasing fraction of this acid as the fermentation progressed. Batch extraction tests that employed the SSF filtrates revealed that soluble lead concentrations as high as 35 mg/l could be achieved. Filtrates containing elevated concentrations of citric acid resulted in the greatest lead extraction while oxalic acid inhibited solubilization. Due to the buffering of pH that was provided by the soil in the batch tests this factor did not appear to influence lead extraction. Lead extraction was observed over an extended period of time in a column test. Lead extraction was strongly influenced by the pH of the soil column and less strongly influenced by the organic acid content of the SSF filtrate. The speciation of organic acids was substantially modified from primarily citric acid in the SSF filtrate to gluconic acid in the soil column discharge.

Brewers’ spent grain (BSG) represents the 85% of the total residue produced during the beer brewing process, with a global annual production volume exceeding 30 Mtons. The current study concerns the application of solid state fermentation (SSF) as a bioprocess where the nutritional value of BSG is improved for further use as animal feed with increased value. The investigated SSF procedure was initiated by the edible fungi Pleurotus ostreatus, which constitutes a natural source of proteins, β-glucans, and various metabolites (vitamins, nutrients, etc.). Herein, the SSF of BSG resulted in a significant increase of protein content by 49.49%, a 10-fold increase of 1,3-1,6 β-glucans, and a respective reduction of cellulose by 11.42%. The application of this method is expected to provide some useful information on the utilization of BSG as substrate for fungi-initiated SSF, a bioprocess allowing the significant reduction of the environmental impact caused by the beer brewing industry and simultaneously producing animal feed with higher protein content and improved nutritional characteristics. Such studies contribute to confront the unavailability of proteinaceous animal feed observed in the last decade.

To explore the comprehensive utilization of agricultural wastes, solid-state fermentation was applied to residues of Flammulina velutipes (F. velutipes) and vinegar for use in culturing earthworms. Fermentation technology and earthworm culture technology were optimized by response surface methodology in this study. The optimal fermentation product for earthworm culture was obtained under an inoculum amount of 7.5%, fermentation temperature of 25.6 °C, pH 7.7 and protein content of 18.23%. The optimum culture conditions were a culture density of 18.4 individuals/dm³, an initial pH of 7.2 and a fermentation temperature of 26.8 °C. The daily weight gain multiplier of earthworms was 0.0387 units, and it increased significantly compared with that of the unfermented and cow dung groups. The fermented product of F. velutipes and vinegar residues could be used to culture earthworms and improve the metabolism and antioxidant capacities of earthworms. This provides a new way to comprehensively utilize agricultural waste resources.

Solid-state fermentation (SSF) of ammoniated corn straw was used to produce feed protein, followed by a toxicological assessment of the fermentation product. Results showed that through ammonification at 35 °C for 9 days and the subsequent SSF by the two fungi Penicillium sp. and Torula allii at 30 °C for 5 days, the contents of real protein and crude protein of the corn straw reached 29.66% and 35.41%, respectively. Toxicological assessment in mice showed that there were no significant differences (P > 0.05) for micronucleated polychromatic erythrocytes (Mn-PCEs) and sperm abnormality between dose groups and the control group. Malondialdehyde (MDA) levels and activities of superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) also showed no significant difference (P > 0.05) between tissues (heart, liver, spleen, stomach, kidney, and brain), which indicates that the fermentation product did not induce toxic effects and is safe to use as ruminant feed.

Bioremediation of textile dyestuffs under solid-state fermentation (SSF) using industrial wastes as substrate pose an economically feasible, promising, and eco-friendly alternative. The purpose of this study was to adsorb Red M5B dye, a sample of dyes mixture and a real textile effluent on distillery industry waste-yeast biomass (DIW-YB) and its further bioremediation using Bacillus cereus EBT1 under SSF. Textile dyestuffs were allowed to adsorb on DIW-YB. DIW-YB adsorbed dyestuffs were decolorized under SSF by using B. cereus. Enzyme analysis was carried out to ensure decolorization of Red M5B. Metabolites after dye degradation were analyzed using UV–Vis spectroscopy, FTIR, HPLC, and GC-MS. DIW-YB showed adsorption of Red M5B, dyes mixture and a textile wastewater sample up to 87, 70, and 81 %, respectively. DIW-YB adsorbed Red M5B was decolorized up to 98 % by B. cereus in 36 h. Whereas B. cereus could effectively reduce American Dye Manufacture Institute value from DIW-YB adsorbed mixture of textile dyes and textile wastewater up to 70 and 100 %, respectively. Induction of extracellular enzymes such as laccase and azoreductase suggests their involvement in dye degradation. Repeated utilization of DIW-YB showed consistent adsorption and ADMI removal from textile wastewater up to seven cycles. HPLC and FTIR analysis confirms the biodegradation of Red M5B. GC-MS analysis revealed the formation of new metabolites. B. cereus has potential to bioremediate adsorbed textile dyestuffs on DIW-YB. B. cereus along with DIW-YB showed enhanced decolorization performance in tray bioreactor which suggests its potential for large-scale treatment procedures.

Sugarcane bagasse, a largely available waste worldwide, was submitted to solid-state fermentation (SSF) using the fungus Metarhizium anisopliae, aiming to produce enzymes. The solid waste generated from SSF was tested as an alternative biosorbent to treat colored effluents containing crystal violet (CV) dye. The biosorbent, here named BW (bagasse waste), was characterized, and experimental tests were performed to verify the influence of pH and dosage on the CV biosorption. Isotherms and biosorption kinetics were performed, and the biosorption thermodynamic parameters were determined. The potential of BW was also evaluated for the treatment of a simulated textile effluent. The maximum biosorption capacity was 131.2 mg g⁻¹ at 328 K, and the Liu was the most appropriate model to represent equilibrium data. The biosorption was spontaneous and endothermic. The use of BW in the simulated effluent showed that it is an efficient material, reaching color removal values of 85%. Therefore, the sugarcane bagasse generated from SSF can be considered a potential biosorbent to remove CV from textile effluents. This finding is relevant from the total environment viewpoint, since, at the same time, SSF generates enzymes and a solid waste, which in turn can be used as biosorbent to treat colored effluents.