Biological Approaches for Extraction of Bioactive Compounds From Agro-industrial By-products: A Review

A Comparative Study of Dairy and Non-Dairy Milk Types: Development and Characterization of Customized Plant-Based Milk Options

Plant-based milk has gained considerable attention; however, its high nutritional variation highlights the need for improved formulation designs to enhance its quality. This study aimed to nutritionally compare cow milk with plant-based milk produced from hazelnuts (H), Brazil nuts (BN), cashew nuts (CN), soybeans (S), and sunflower seeds (SS), and to perform physicochemical and technological characterization. The plant-based milk produced with isolated grains showed a nutritional composition inferior to that of cow milk in almost all evaluated parameters, protein content (up to 1.1 g 100 g-1), lipids (up to 2.7 g 100 g-1), color parameters, minerals, and especially calcium (up to 62.4 mg L-1), which were originally high in cow milk (up to 1030 mg L-1). However, the plant-based milk designed using a blend composition was able to promote nutritional enhancement in terms of minerals, especially iron (Fe) and magnesium (Mg), high-quality lipids (up to 3.6 g 100 g-1), and carbohydrates (3.4 g 100 g-1 using CN, BN, and S). The protein content was 1.3% compared to 5.7 in cow milk, and the caloric value of plant-based milk remained 32.8 at 52.1 kcal, similar to cow milk. Satisfactory aspects were observed regarding the shelf life, especially related to microbiological stability during the 11 d of storage at 4 °C. For the designed plant-based milk to be equivalent to cow milk, further exploration for optimizing the blends used to achieve better combinations is required. Furthermore, analyzing possible fortification and preservation methods to increase shelf life and meet the nutritional and sensory needs of the public would be interesting.

Isolation of bioactive compounds from low-cost agricultural resources and its utilization in daily life

The ethanolic (80 %), methanolic (80 %) and aqueous decoction (100 % distilled water) of whole plant of Oxalis corniculata Linn (Indian Sorrel) was evaluated for its anti-microbial and antioxidant properties by in vitro methods. Methanolic (80 %) and ethanolic (80 %) decoctions showed significant antibacterial property against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Salmonella typhi bacterial strains. In comparison to Chloramphenicol (C30) against bacteria, 80 % ethanolic decoctions showed significant effect, among the decoctions. Nowadays though the standard soap is in huge demand but it's also facing major backlash due to the presence of synthetic compounds in it, which over long use may cause harmful effects on the skin health. Therefore, the organic soaps which are made up of natural ingredients, herbs or any sort Ayurvedic compound have fewer side effects on the human skin and are much safer than standard daily soap. The formulated therapeutic soap exhibits a significant amount of reducing potential (high FRAP and TAC values) and antioxidant activity (DPPH, ABTS assay).

Agro-Industrial By-Products of Plant Origin: Therapeutic Uses as well as Antimicrobial and Antioxidant Activity

The importance of bioactive compounds in agro-industrial by-products of plant origin lies in their direct impacts on human health. These compounds have been shown to possess antioxidant, anti-inflammatory, and antimicrobial properties, contributing to disease prevention and strengthening the immune system. In particular, the antimicrobial action of these compounds emerges as an important tool in food preservation, providing natural alternatives to synthetic preservatives and contributing to combating antimicrobial resistance. Using agro-industrial by-products of plant origin not only addresses the need to reduce waste and promote sustainability but also inaugurates a new era in the formulation of functional foods. From fruit peels to pulps and seeds, these by-products are emerging as essential ingredients in the creation of products that can promote health. Continued research in this area will unveil new applications and properties of these by-products and open doors to a food paradigm in which health and sustainability converge, paving the way to a healthier and more equitable future. The present review presents an overview of our knowledge of agro-industrial by-products and some of their more relevant health-promoting bioactivities.

The utilisation of agricultural by-products in processed meat products: Effects on physicochemical, nutritional and sensory quality - Invited Review

Several plant-based materials are discarded by the food industry due to oversupply, lack of transport, and inappropriate storage. These materials contain valuable essential micronutrients such as minerals, vitamins and bioactive components (e.g., polyphenol, tocopherols, ascorbic acid, carotenoids) with antioxidant, antimicrobial, and anti-inflammatory effects, among others. In the context of making our agriculture-food based economy more circular and sustainable, and to develop foods with clean labels and less E-numbers, fruits, vegetables, yams, cereal distillers, oilseeds and other plant by-products could be utilised and upcycled back into new food formulations. Meat products are a particularly suitable matrix for this purpose, due to their susceptibility to lipid and protein oxidation and microbial spoilage (which shorten their shelf life). This review brings together the latest (2020-23) reformulation efforts, preservative methods and other innovative pathways, including studies on by-products as plant-based additives and bio-actives. It will cover the use of plant-based by-products as natural additives into production of processed meat products such as burgers, fermented meats and sausages, produced from ruminant and monogastric animals (except poultry). The extraction methods, inclusion levels, processing methods used and the quality of the resulting meat products will be reported, including preservative effects (microbial growth, oxidative stability and shelf life) and effects on instrumental, nutritional and sensory quality. Furthermore, it will also critically discuss the gaps identified, recommendation of the most promising ingredients for quality enhancement, and provide directions for future research.

Current situation, trend, and prospects of research on functional components from by-products of baijiu production: A review

In the present scenario marked by energy source shortages and escalating concerns regarding carbon dioxide emissions, there is a growing emphasis on the optimal utilization of biomass resources. Baijiu, as the Chinese national spirit, boasts remarkably high sales volumes annually. However, the production of baijiu yields various by-products, including solid residues (Jiuzao), liquid wastewater (Huangshui and waste alcohol), and gaseous waste. Recent years have witnessed dedicated research aimed at exploring the composition and potential applications of these by-products, seeking sustainable development and comprehensive resource utilization. This review systematically summarizes recent research, shedding light on both the baijiu brewing process and the bioactive compounds present baijiu production by-products (BPBPs). The primary focus lies in elucidating the potential extraction methods and applications of BPBPs, offering a practical approach to comprehensive utilization of by-products in functional food, medicine, cosmetic, and packaging fields. These applications not only contribute to enhancing production efficiency and mitigating environmental pollution, but also introduce innovative concepts for the sustainable advancement of associated industries. Future research avenues may include more in-depth compositional analysis, the development of utilization technologies, and the promotion of potential industrialization.

Intelligent and active biodegradable biopolymeric films containing carotenoids

There is growing interest in the use of natural bioactive compounds for the development of new bio-based materials for intelligent and active food packaging applications. Several beneficial effects have been associated with the antioxidant and antimicrobial potentials of carotenoid compounds. In addition, carotenoids are sensitive to pH changes and oxidation reactions, which make them useful bioindicators of food deterioration. This review summarizes the current research on the application of carotenoids as novel intelligent and active biodegradable food packaging materials. Carotenoids recovered from food processing by-products can be used in the development of active food packaging materials due to their antioxidant properties. They help maintain the stability of lipid-rich foods, such as vegetable oils. Additionally, when incorporated into films, carotenoids can monitor food oxidation, providing intelligent functionalities.

Targeted metabolite profiling of Salvia rosmarinus Italian local ecotypes and cultivars and inhibitory activity against Pectobacterium carotovorum subsp. carotovorum

Introduction

The development of agriculture in terms of sustainability and low environmental impact is, at present, a great challenge, mainly in underdeveloped and marginal geographical areas. The Salvia rosmarinus "Eretto Liguria" ecotype is widespread in Liguria (Northwest Italy), and farmers commonly use it by for cuttings and for marketing. In the present study, this ecotype was characterized in comparison with other cultivars from the same geographical region and Campania (Southern Italy), with a view to application and registration processes for the designation of protected geographical indications. Moreover, the possibility of using the resulting biomass after removing cuttings or fronds as a source of extracts and pure compounds to be used as phytosanitary products in organic farming was evaluated. Specifically, the potential of rosemary extracts and pure compounds to prevent soft rot damage was then tested.

Methods

A targeted NMR metabolomic approach was employed, followed by multivariate analysis, to characterize the rosemary accessions. Bacterial soft rot assay and disk diffusion test were carried out to evaluate the activity of extracts and isolated compounds against Pectobacterium carotovorum subsp. carotovorum. Enzymatic assay was performed to measure the in vitro inhibition of the pectinase activity produced by the selected pathogen. Molecular docking simulations were used to explore the possible interaction of the selected compounds with the pectinase enzymes.

Results and Discussion

The targeted metabolomic analysis highlighted those different geographical locations can influence the composition and abundance of bioactive metabolites in rosemary extracts. At the same time, genetic factors are important when a single geographical area is considered. Self-organizing maps (SOMs) showed that the accessions of "Eretto Liguria" appeared well characterized when compared to the others and had a good content in specialized metabolites, particularly carnosic acid. Soft rotting Enterobacteriaceae belonging to the Pectobacterium genus represent a serious problem in potato culture. Even though rosemary methanolic extracts showed a low antibacterial activity against a strain of Pectobacterium carotovorum subsp. carotovorum in the disk diffusion test, they showed ability in reducing the soft rot damage induced by the bacterium on potato tissue. 7-O-methylrosmanol, carnosol and isorosmanol appeared to be the most active components. In silico studies indicated that these abietane diterpenoids may interact with P. carotovorum subsp. carotovorum pectate lyase 1 and endo-polygalacturonase, thus highlighting these rosemary components as starting points for the development of agents able to prevent soft rot progression.

Extraction and Separation of Natural Products from Microalgae and Other Natural Sources Using Liquefied Dimethyl Ether, a Green Solvent: A Review

Microalgae are a sustainable source for the production of biofuels and bioactive compounds. This review discusses significant research on innovative extraction techniques using dimethyl ether (DME) as a green subcritical fluid. DME, which is characterized by its low boiling point and safety as an organic solvent, exhibits remarkable properties that enable high extraction rates of various active compounds, including lipids and bioactive compounds, from high-water-content microalgae without the need for drying. In this review, the superiority of liquefied DME extraction technology for microalgae over conventional methods is discussed in detail. In addition, we elucidate the extraction mechanism of this technology and address its safety for human health and the environment. This review also covers aspects related to extraction equipment, various applications of different extraction processes, and the estimation and trend analysis of the Hansen solubility parameters. In addition, we anticipate a promising trajectory for the expansion of this technology for the extraction of various resources.

Valorization of Food Waste into Single-Cell Protein: An Innovative Technological Strategy for Sustainable Protein Production

The rapidly increasing population and climate change pose a great threat to our current food systems. Moreover, the high usage of animal-based and plant-based protein has its drawbacks, as these nutritional sources require many hectares of land and water, are affected by seasonal variations, are costly, and contribute to environmental pollution. Single-cell proteins (SCPs) are gaining a lot of research interest due to their remarkable properties, such as their high protein content that is comparable with other protein sources; low requirements for land and water; low carbon footprint; and short production period. This review explores the use of food waste as a sustainable feedstock for the advancement of SCP processes. It discusses SCP studies that exploit food waste as a substrate, alongside the biocatalysts (bacteria, fungi, yeast, and microalgae) that are used. The operational setpoint conditions governing SCP yields and SCP fermentation routes are elucidated as well. This review also demonstrates how the biorefinery concept is implemented in the literature to improve the economic potential of "waste-to-protein" innovations, as this leads to the establishment of multiproduct value chains. A short section that discusses the South African SCP scenario is also included. The technical and economic hurdles facing second-generation SCP processes are also discussed, together with future perspectives. Therefore, SCP technologies could play a crucial role in the acceleration of a "sustainable protein market", and in tackling the global hunger crisis.

Isolation, identification, and biological characterization of bacterial endophytes isolated from Gunnera perpensa L

In the present study, eleven endophytic bacterial strains, Herbaspirillum sp. (GP-SGM1, GP-SGM2, GP-SGM3, and GP-SGM11), Pseudomonas sp. (GP-SGM4, GP-SGM5), Novosphingobium sp. GP-SGM6, Chryseobacterium sp. GP-SGM7, Labedella sp. GP-SGM8, Brevibacterium sp. GP-SGM9, and Pseudomonas sp. GP-SGM10, were isolated from the rhizomes of Gunnera perpensa L. The growth kinetics, assessed through maximum growth rates (μmax) and optical density (OD) values, revealed that GP-SGM7 exhibited highest μmax values of 0.33 ± 0.01 hours (h)-1 with an OD of 4.20 ± 0.04. In contrast, GP-SGM11 exhibited the lowest μmax of 0.12 ± 0.05 h-1 and the smallest OD of 1.50 ± 0.00. In addition, the endophyte crude extracts were tested for antibacterial activity against five pathogenic strains using the disk diffusion method, with GP-SGM7 crude extracts exhibiting promising antibacterial activity against Klebsiella pneumoniae and Staphylococcus aureus. Antioxidant activity was determined by DPPH (2, 2-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) assays. The crude extracts of GP-SGM1, GP-SGM7, GP-SGM9, and GP-SGM10 were the most effective at scavenging DPPH radicals, with GP-SGM7 also exhibiting a high FRAP value of 0.54 ± 0.01. These findings emphasize the therapeutic potential of endophytic bacteria from G. perpensa L. in addressing skin-related issues, including bacterial infections and free radicals.

Pulp from Colored Potatoes (Solanum tuberosum L.) as an Ingredient Enriching Dessert Cookies

Freeze-dried pulp from colored potatoes, obtained after starch isolation, is a rich source of polyphenols. Therefore, it can be used to fortify cookies, contributing to a reduction in industrial waste, aligning with the zero-waste technology. The purpose of this study was to analyze the effects of adding 5% and 10% pulp from two varieties of colored potatoes on the content of polyphenols, antioxidant activity, physical characteristics, nutritional composition, and the levels of hydroxymethylfurfural and acrylamide of the fortified cookies. The findings revealed that colored potato pulp is an outstanding additive for fortifying cookies with polyphenols, flavonoids, anthocyanins, and flavonols (even two to four times in comparison to control). Cookies containing pulp exhibited even two times higher fiber and protein content (up to 17% more), while the fat and ash content remained unchanged compared to control cookies. Furthermore, they contained 30% less HMF and 40% more acrylamide. These cookies also exhibited good physical properties in the final products. The study demonstrated that pulp from the "Magenta Love" potato variety was significantly more effective in enriching cookies with health-promoting compounds and nutrition value compared to pulp from Marleta Blue.

Extraction and chemical characterisation of agro-waste from turmeric leaves as a source of bioactive essential oils with insecticidal and antioxidant activities

Turmeric (Curcuma longa L.) is a significant crop that has historically been used worldwide as a medicinal plant, spice, food colouring agent, and a significant ingredient in cosmetic industries. After harvesting rhizomes, leaves are considered waste material. This research study aims to extract and chemically characterise the essential oil from the leaves waste of turmeric with an evaluation of different insecticidal, antioxidant, and phytotoxic activities. Subsequently, the contact toxicity, fumigant toxicity, and repellent activity were evaluated against two key stored grain insect species. The gas chromatography-mass spectrometry (GC-MS) characterisation revealed that α-phellandrene (28.95%), 2-carene (16.51%), eucalyptol (10.54%) and terpinolene (10.24%) were the major chemical constituents. The study's findings on the insecticidal effects of essential oils extracted from turmeric leaves revealed noteworthy repellent, contact (at 24 h, LC50 = 6.51 mg/cm2 for Tribolium castaneum and LC50 = 4.74 mg/cm2 for Rhyzopertha dominica) and fumigant toxicities (at 24 h, LC50 = 2.57 mg/L air for T. castaneum and LC50 = 2.83 mg/L air for R. dominica), against two key stored grain insects. In addition, turmeric leaf essential oil showed notable antioxidant activity (IC50 = 10.04 ± 0.03 µg/mL for DPPH assay; IC50 = 14.12 ± 0.21 µg/mL for ABTS assay. Furthermore, a phytotoxicity study was carried out on stored paddy seeds and no toxic effects were found on germination rate and seedling growth. So, it might be expected that the essential oils extracted from the turmeric leaf waste could be valorised and demonstrate their potential as safe botanical insecticides against stored-product insects, with noble antioxidant properties.

Employing alternative culture media in kefiran exopolysaccharide production: Impact on microbial diversity, physicochemical properties, and bioactivities

Kefiran is a biomaterial with potential application in developing novel materials for food technology. In this study, sugarcane sugar (REF), raw sugar (RAS), brown sugar (BRS), soy molasses (SOM), and sugarcane molasses (SCM) were evaluated for the production of kefiran from kefir biomass rather than cow's milk (CMK), the usual medium. The produced kefiran was purified and characterized by colorimetry, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis, and morphology. It was also assayed for antioxidant and antimicrobial activity. SCM had the highest average daily rate of kefir biomass production (29.17 %/day). The composition of the culture medium affected the microbial diversity of kefir grains, and the Lactobacillus genus was the most abundant (39.8 %, 40.0 %, and 83.9 % to SCM, SOM, and CMK, respectively) in the samples that presented the highest biomass production and kefiran extraction yields. FTIR spectra showed that the bands of kefiran produced in REF and RAS were narrower than those of the other samples. Kefiran grew in an alternative culture medium also exhibited higher thermal stability (Tonset and TMax was higher than 250 and 280 °C, respectively). Those grown in SOM and SCM displayed antimicrobial and antioxidant activities similar to those of kefiran produced in CMK. The results indicate that agro-industrial by-products (SCM and SOM) are potential alternatives for kefiran production from kefir biomass.

Use of an Innovative Silage of Agro-Industrial Waste By-Products in Pig Nutrition: A Pilot Study of Its Effects on the Pig Gastrointestinal Microbiota

The aim of this study was to evaluate whether dietary supplementation with an innovative silage (IS) created using 60% olive mill waste, 20% grape pomace, and 20% deproteinised feta cheese waste solids can modulate the composition of the intestinal microbiota in weaned (Exp. 1) and finishing (Exp. 2) pigs. In Exp. 1 (40 day supplementation), forty-five crossbred weaned pigs were randomly assigned to the 0% (Control), 5%, or 10% IS groups (15 replicates/experimental diet). In Exp. 2 (60 day supplementation), eighteen finishing pigs from Exp. 1 were fed the control diet for 8 weeks before being re-assigned to their original experimental groups and fed with the 0% (Control), 5%, or 10% IS diets (six replicates/experimental diet). Performance parameters were recorded. Ileal and caecal digesta and mucosa were collected at the end of each experiment for microbiota analysis using 16S rRNA gene sequencing (five pigs/experimental diet for Exp. 1 and six pigs/experimental diet for Exp. 2). No significant effects on pig growth parameters were observed in both experiments. In Exp. 1, 5% IS supplementation increased the relative abundance of the Prevotellaceae family, Coprococcus genus, and Alloprevotella rava (OTU_48) and reduced the relative abundance of Lactobacillus genus in the caecum compared to the control and/or 10% IS diets (p < 0.05). In Exp. 2, 5% IS supplementation led to compositionally more diverse and different ileal and caecal microbiota compared to the control group (p < 0.05; p = 0.066 for β-diversity in ileum). Supplementation with the 5% IS increased the relative abundance of Clostridium celatum/disporicum/saudiense (OTU_3) in the ileum and caecum and Bifidobacterium pseudolongum (OTU_17) in the caecum and reduced the relative abundance of Streptococcus gallolyticus/alactolyticus (OTU_2) in the caecum compared to the control diet (p < 0.05). Similar effects on C. celatum/disporicum/saudiense and S. gallolyticus/alactolyticus were observed with the 10% IS diet in the caecum (p < 0.05). IS has the potential to beneficially alter the composition of the gastrointestinal microbiota in pigs.

Recent advances in bio-based extraction processes for the recovery of bound phenolics from agro-industrial by-products and their biological activity

Usually found bound to other complex molecules (e.g., lignin, hemicellulose), phenolic compounds (PC) are widely present in agro-industrial by-products, and their extraction is challenging. In recent times, research is starting to highlight the bioactive roles played by bound phenolics (BPC) in human health. This review aims at providing a critical update on recent advances in green techniques for the recovery of BPC, focusing on enzymatic-assisted (EAE) and fermentation-assisted extraction (FAE) as well as in the combination of technologies, showing variable yield and features. The present review also summarizes the most recent biological activities attributed to BPC extracts until now. The higher antioxidant activity of BPC-compared to FPC-coupled with their affordable by-product source make them medicinally potent and economically viable, promoting their integral upcycling and generating new revenue streams, business, and employment opportunities. In addition, EAE and FAE can have a biotransformative effect on the PC itself or its moiety, leading to improved extraction outcomes. Moreover, recent research on BPC extracts has reported promising anti-cancer and anti-diabetic activity. Yet further research is needed to elucidate their biological mechanisms and exploit the true potential of their applications in terms of new food products or ingredient development for human consumption.

Emulsion-Based Delivery Systems to Enhance the Functionality of Bioactive Compounds: Towards the Use of Ingredients from Natural, Sustainable Sources

In recent years, the trend in the population towards consuming more natural and sustainable foods has increased significantly. This claim has led to the search for new sources of bioactive compounds and extraction methods that have less impact on the environment. Moreover, the formulation of systems to protect these compounds is also focusing on the use of ingredients of natural origin. This article reviews novel, natural alternative sources of bioactive compounds with a positive impact on sustainability. In addition, it also contains information on the most recent studies based on the use of natural (especially from plants) emulsifiers in the design of emulsion-based delivery systems to protect bioactive compounds. The properties of these natural-based emulsion-delivery systems, as well as their functionality, including in vitro and in vivo studies, are also discussed. This review provides relevant information on the latest advances in the development of emulsion delivery systems based on ingredients from sustainable natural sources.

Statistical improvement of protease production from a new isolate Bacillus thuringiensis strain-MA8 and its application in the production of enzyme-modified cheese

Enzyme-modified cheese (EMC) is a concentrated cheese flavor that is produced enzymatically from dairy substrates to provide an intense source of cheese flavor with broad applications. In this study, EMC was produced by enzymatic biotransformation from a new bacterial isolate described and molecularly identified as Bacillus thuringiensis strain-MA8. Optimization of protease production conditions using one-variable-at-a-time followed by multi-factorial (Plackett-Burman and Box-Behnken) designs increased production by 7-fold. Protease was used at different concentrations (300 and 900 U/100 g curd) as a cost-effective source of concentrated cheese flavor in the EMC preparation. Sensorial evaluation of EMC revealed that the overall acceptability, flavor, and texture were improved from the 2nd day compared to the control, and then decreased on the 4th day without any apparent bitterness. The chemical characteristics of EMC showed that the addition of protease extracts increased the total volatile fatty acids, water-soluble nitrogen, and acidity of EMC significantly (p≤0.05) compared to the control. The amino acids profile revealed that EMC1 which was treated with (300 U/100 g curd) protease had the highest essential amino acids (EAA) and EAA/total amino acids ratio. Nutritional parameters including protein efficiency ratio, biological value, and chemical score of EMC were higher than control based on Val, Met + Cys, Ile, Leu, and Phe + Tyr amino acids. Also, Scanning Electron Microscopy showed significant changes in EMC compared to the control. In conclusion, the addition of (300 U/100g curd) of protease revealed good EMC characteristics without any apparent defect.

Aqueous Two-Phase Systems Based on Ionic Liquids and Deep Eutectic Solvents as a Tool for the Recovery of Non-Protein Bioactive Compounds—A Review

Aqueous two-phase systems (ATPS) based on ionic liquids (IL) and deep eutectic solvents (DES) are ecofriendly choices and can be used to selectively separate compounds of interest, such as bioactive compounds. Bioactive compounds are nutrients and nonnutrients of animal, plant, and microbial origin that benefit the human body in addition to their classic nutritional properties. They can also be used for technical purposes in food and as active components in the chemical and pharmaceutical industries. Because they are usually present in complex matrices and low concentrations, it is necessary to separate them in order to increase their availability and stability, and ATPS is a highlighted technique for this purpose. This review demonstrates the application of ATPS based on IL and DES as a tool for recovering nonprotein bioactive compounds, considering critical factors, results and the most recent advances in this field. In addition, the review emphasizes the perspectives for expanding the use of nonconventional ATPS in purification systems, which consider the use of molecular modelling to predict experimental conditions, the investigation of diverse compounds in phase-forming systems, the establishment of optimal operational parameters, and the verification of bioactivities after the purification process.

Secretion of collagenases by Saccharomyces cerevisiae for collagen degradation

Background

The production and processing of animal-based products generates many collagen-rich by-products, which have received attention both for exploitation to increase their added value and to reduce their negative environmental impact. The collagen-rich by-products can be hydrolyzed by collagenases for further utilization. Therefore, collagenases are of benefit for efficient collagen materials processing. An alternative and safe way to produce secreted collagenases is needed.

Results

Two collagenases from Hathewaya histolytica, ColG and ColH, were successfully secreted by the yeast Saccharomyces cerevisiae. Compared with the native signal peptide of collagenase, the α-factor leader is more efficient in guiding collagenase secretion. Collagenase secretion was significantly increased in YPD medium by supplementing with calcium and zinc ions. Recombinant collagenase titers reached 68 U/mL and 55 U/mL for ColG and ColH, respectively. Collagenase expression imposed metabolic perturbations on yeast cells; substrate consumption, metabolites production and intracellular cofactor levels changed in engineered strains. Both recombinant collagenases from yeast could hydrolyze soluble and insoluble collagen materials. Recombinant ColG and ColH showed a synergistic effect on efficient collagen digestion.

Conclusions

Sufficient calcium and zinc ions are essential for active collagenase production by yeast. Collagenase secretion was increased by optimization of expression cassettes. Collagenase expression imposed metabolic burden and cofactor perturbations on yeast cells, which could be improved through metabolic engineering. Our work provides a useful way to produce collagenases for collagen resource utilization.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13068-022-02186-y.

A Temporal Evolution Perspective of Lipase Production by Yarrowia lipolytica in Solid-State Fermentation

Lipases are enzymes that, in aqueous or non-aqueous media, act on water-insoluble substrates, mainly catalyzing reactions on carboxyl ester bonds, such as hydrolysis, aminolysis, and (trans)esterification. Yarrowia lipolytica is a non-conventional yeast known for secreting lipases and other bioproducts; therefore, it is of great interest in various industrial fields. The production of lipases can be carried on solid-state fermentation (SSF) that utilizes solid substrates in the absence, or near absence, of free water and presents minimal problems with microbial contamination due to the low water contents in the medium. Moreover, SSF offers high volumetric productivity, targets concentrated compounds, high substrate concentration tolerance, and has less wastewater generation. In this sense, the present work provides a temporal evolution perspective regarding the main aspects of lipase production in SSF by Y. lipolytica, focusing on the most relevant aspects and presenting the potential of such an approach.