Trends in recombinant protein use in animal production

Effect of an equine chorionic gonadotrophin-like recombinant glycoprotein treatment on fertility in Angus cattle

This study determined the effects of administering a glycoprotein with equine chorionic gonadotropin (eCG)-like activity (eCG-like) on corpus luteum (CL) area, serum progesterone concentrations, incidence of multiple ovulations (MOV), estrus expression rate (EER), and pregnancy to timed AI (P/TAI) in Angus cattle synchronized with a 5-d Co-Synch protocol. On Day -8, cattle were body condition scored (BCS), and received a 1.0 g progesterone intravaginal device (IVD) and 100 μg GnRH. On Day -3, the IVDs were removed and 500 μg cloprostenol was administered intramuscularly (i.m.). Cattle were randomly assigned into one of two groups: eCG-like (heifers, n = 232, primiparous, n = 148, and multiparous cows = 485; 300 IU (heifers) and 400 IU (cows) eCG-like i.m. on Day -3), or Control (heifers, n = 240, primiparous, n = 151, and multiparous cows, n = 478; no eCG-like). On Day -2, cattle received a second dose of 500 μg cloprostenol, and on Day 0, 100 μg GnRH was given concurrently with TAI. Estrus expression rate was assessed by observing the tail paint rubbed off in a subset of heifers (n = 372) and all cows on Day 0. Transrectal ultrasonography was used to evaluate the presence of CL on Day -8 and to diagnose P/TAI on Day 30-35. In a subset of cattle (heifers = 194 and multiparous cows = 87), CL area, serum progesterone concentrations, and incidence of MOV were evaluated on Day 7. Heifers, primiparous, and multiparous cows were analyzed separately. Treatment with eCG-like did not affect (P > 0.1) EER in heifers. Estrus expression rate was increased (P ≤ 0.03) in primiparous (68.9 % vs 45.0 %) and multiparous (75.5 % vs. 68.8 %) cows treated with eCG-like compared with Controls. Pregnancy/TAI was increased (P < 0.01) in heifers (65.2 % vs 48.3 %) and primiparous cows (48.3 % vs. 35.1 %) treated with eCG-like than Controls. In multiparous cows with a BCS ≤4 P/TAI was increased (P = 0.03) in the eCG-like group (47.7 %) than the Control group (34.8 %) but was similar (P > 0.1) between treatment groups in multiparous cows with a BCS ≥4.5. The eCG-like treatment increased (P < 0.05) CL area in heifers and multiparous cows and tended (P = 0.10) to elevate serum progesterone concentrations only in heifers. However, it did not affect (P > 0.1) the incidence of MOV in heifers and multiparous cows. Glycoprotein eCG-like administration increased fertility in heifers and primiparous cows, but in multiparous the effect of eCG-like on fertility was associated with BCS.

A review on camelid nanobodies with potential application in veterinary medicine

The single variable domains of camelid heavy-chain only antibodies, known as nanobodies, have taken a long journey since their discovery in 1989 until the first nanobody-based drug's entrance to the market in 2022. On account of their unique properties, nanobodies have been successfully used for diagnosis and therapy against various diseases or conditions. Although research on the application of recombinant antibodies has focused on human medicine, the development of nanobodies has paved the way for incorporating recombinant antibody production in favour of veterinary medicine. Currently, despite many efforts in developing these biomolecules with diversified applications, significant opportunities exist for exploiting these highly versatile and cost-effective antibodies in veterinary medicine. The present study attempts to identify existing gaps and shed light on paths for future research by presenting an updated review on camelid nanobodies with potential applications in veterinary medicine.

Fermenter scale production of recombinant beta-mannanase by E. coli BL21 cells under microaerobic environment

Aim of the study was to optimize and produce beta-mannanase at fermenter scale by using cheaper minimal media. Increased production of beta-mannanase from Microbacterium camelliasinensis CIAB417 was achieved by heterologous expression in E. coli BL21 (DE3). The scale-up production of beta-mannanase was optimized from shake flask to 5-L fermenter. The cost-effective minimal media (M9+e) without any vitamins was found to be most effective and optimized for culturing the cells. The same media displayed no significant fluctuation in the pH while culturing the cells for the production of beta-mannanase both at shake flask and fermenter level. Additionally, E. coli cells were able to produce similar amount of dry cell weight and recombinant beta-mannanase both in the presence of micro and macro-oxygen environment. The optimized media was demonstrated to show no significant drop in pH throughout the recombinant protein production process. In one litre medium, 2.0314 g dry weight of E. coli cells yielded 1.8 g of purified recombinant beta-mannanase. The purified enzyme was lyophilized and demonstrated to hydrolyse locust bean gum to release mannooligosaccharides.

Expression and functional characterization of chimeric recombinant bovine follicle-stimulating hormone produced in Leishmania tarentolae

Assisted reproductive techniques are routinely used in livestock species to increase and enhance productivity. Ovarian hyperstimulation is a process that currently relies on administering pituitary-derived follicle-stimulating hormone (FSH) or equine chorionic gonadotropin in combination with other hormones to promote the maturation of multiple follicles and thereby achieve superovulation. The use of partially purified preparations of FSH extracted from natural sources is associated with suboptimal and variable results. Recombinant FSH (rFSH) has been produced in a variety of heterologous organisms. However, attaining a bioactive rFSH of high quality and at low cost for use in livestock remains challenging. Here we report the production and characterization of a single chain bovine rFSH consisting of the β- and α-subunit fused by a polypeptide linker (scbFSH) using Leishmania tarentolae as heterologous expression system. This unicellular eukaryote is non-pathogenic to mammals, can be grown in bioreactors using simple and inexpensive semisynthetic media at 26°C and does not require CO2 or bovine serum supplementation. Stable cell lines expressing scbFSH in an inducible fashion were generated and characterized for their productivity. Different culture conditions and purification procedures were evaluated, and the recombinant product was biochemically and biologically characterized, including bioassays in an animal model. The results demonstrate that L. tarentolae is a suitable host for producing a homogeneous, glycosylated and biologically active form of scbFSH with a reasonable yield.

Novel Enhanced Mammalian Cell Transient Expression Vector via Promoter Combination

During the emergence of infectious diseases, evaluating the efficacy of newly developed vaccines requires antigen proteins. Available methods enhance antigen protein productivity; however, structural modifications may occur. Therefore, we aimed to construct a novel transient overexpression vector capable of rapidly producing large quantities of antigenic proteins in mammalian cell lines. This involved expanding beyond the exclusive use of the human cytomegalovirus (CMV) promoter, and was achieved by incorporating a transcriptional enhancer (CMV enhancer), a translational enhancer (woodchuck hepatitis virus post-transcriptional regulatory element), and a promoter based on the CMV promoter. Twenty novel transient expression vectors were constructed, with the vector containing the human elongation factor 1-alpha (EF-1a) promoter showing the highest efficiency in expressing foreign proteins. This vector exhibited an approximately 27-fold higher expression of enhanced green fluorescent protein than the control vector containing only the CMV promoter. It also expressed the highest level of severe acute respiratory syndrome coronavirus 2 receptor-binding domain protein. These observations possibly result from the simultaneous enhancement of the transcriptional activity of the CMV promoter and the human EF-1a promoter by the CMV enhancer. Additionally, the synergistic effect between the CMV and human EF-1a promoters likely contributed to the further enhancement of protein expression.

Heterologous Expression of Difficult to Produce Proteins in Bacterial Systems

Proteins play a crucial role in maintaining homeostasis, providing structure, and enabling various functions in biological systems [...].

Lactiplantibacillus plantarum: a new example of inclusion body producing bacteria

BACKGROUND

Lactic Acid Bacteria such as Lactococcus lactis, Latilactobacillus sakei (basonym: Lactobacillus sakei) and Lactiplantibacillus plantarum (basonym: Lactobacillus plantarum) have gained importance as recombinant cell factories. Although it was believed that proteins produced in these lipopolysaccharides (LPS)-free microorganisms do not aggregate, it has been shown that L. lactis produce inclusion bodies (IBs) during the recombinant production process. These protein aggregates contain biologically active protein, which is slowly released, being a biomaterial with a broad range of applications including the obtainment of soluble protein. However, the aggregation phenomenon has not been characterized so far in L. plantarum. Thus, the current study aims to determine the formation of protein aggregates in L. plantarum and evaluate their possible applications.

RESULTS

To evaluate the formation of IBs in L. plantarum, the catalytic domain of bovine metalloproteinase 9 (MMP-9cat) protein has been used as model protein, being a prone-to-aggregate (PTA) protein. The electron microscopy micrographs showed the presence of electron-dense structures in L. plantarum cytoplasm, which were further purified and analyzed. The ultrastructure of the isolated protein aggregates, which were smooth, round and with an average size of 250-300 nm, proved that L. plantarum also forms IBs under recombinant production processes of PTA proteins. Besides, the protein embedded in these aggregates was fully active and had the potential to be used as a source of soluble protein or as active nanoparticles. The activity determination of the soluble protein solubilized from these IBs using non-denaturing protocols proved that fully active protein could be obtained from these protein aggregates.

CONCLUSIONS

These results proved that L. plantarum forms aggregates under recombinant production conditions. These aggregates showed the same properties as IBs formed in other expression systems such as Escherichia coli or L. lactis. Thus, this places this LPS-free microorganism as an interesting alternative to produce proteins of interest for the biopharmaceutical industry, which are obtained from the IBs in an important number of cases.

Development of efficient modules for recombinant protein expression and periplasmic localiszation in Pseudomonas bharatica CSV86T

Escherichia coli has been widely employed as a host for heterologous protein expression. However, due to certain limitations, alternative hosts like Pseudomonas, Lactococcus and Bacillus are being explored. Pseudomonas bharatica CSV86^T, a novel soil isolate, preferentially degrades wide range of aromatics over simple carbon sources like glucose and glycerol. Strain also possesses advantageous eco-physiological traits, making it an ideal host for engineering xenobiotic degradation pathways, which necessitates the development of heterologous expression systems. Based on the efficient growth, short lag-phase and rapid metabolism of naphthalene, Pnah and Psal promoters (regulated by NahR) were selected for expression. Pnah was found to be strong and leaky as compared to Psal, using 1-naphthol 2-hydroxylase (1NH, ∼66 kDa) as reporter gene in strain CSV86^T. The Carbaryl hydrolase (CH, ∼72kDa) from Pseudomonas sp. C5pp was expressed under Pnah in strain CSV86^T and could successfully be translocated to the periplasm due to the presence of the Tmd + Sp sequence. The recombinant CH was purified from the periplasmic fraction and the kinetic characteristics were found to be similar to the native protein from strain C5pp. These results potentiate the suitability of P. bharatica CSV86^T as a desirable host, while Pnah and the Tmd + Sp can be employed for overexpression and periplasmic localisation, respectively. Such tools find application in heterologous protein expression and metabolic engineering applications.

Valorization of bioethanol by-products to produce unspecific peroxygenase with Agrocybe aegerita: technological and proteomic perspectives

Unspecific peroxygenase (UPO) presents a wide range of biotechnological applications. This study targets the use of by-products from bioethanol synthesis to produce UPO by Agrocybe aegerita. Solid-state and submerged fermentations (SSF and SmF) were evaluated, achieving the highest titers of UPO and laccase in SmF using vinasse as nutrients source. Optimized UPO production of 331U/L was achieved in 50% (v:v) vinasse with an inoculum grown for 14 days. These conditions were scaled-up to a 4L reactor, achieving a UPO activity of 265U/L. Fungal proteome expression was analyzed before and after UPO activity appeared by shotgun mass spectrometry proteomics. Laccase, dye-decolorizing peroxidases (DyP), lectins and proteins involved in reactive oxygen species (ROS) production and control were detected (in addition to UPO). Interestingly, the metabolism of complex sugars and nitrogen sources had a different activity at the beginning and end of the submerged fermentation. DATA AVAILABILITY: The data used to support the findings of this study are available from the corresponding author upon reasonable request.

Factors involved in heterologous expression of proteins in E. coli host

The production of recombinant proteins is one of the most significant achievements of biotechnology in the last century. These proteins are produced in the eukaryotic or prokaryotic heterologous hosts. By increasing the omics data especially related to different heterologous hosts as well as the presence of new amenable genetic engineering tools, we can artificially engineer heterologous hosts to produce recombinant proteins in sufficient quantities. Numerous recombinant proteins have been produced and applied in various industries, and the global recombinant proteins market size is expected to be cast to reach USD 2.4 billion by 2027. Therefore, identifying the weakness and strengths of heterologous hosts is critical to optimize the large-scale biosynthesis of recombinant proteins. E. coli is one of the popular hosts to produce recombinant proteins. Scientists reported some bottlenecks in this host, and due to the increasing demand for the production of recombinant proteins, there is an urgent need to improve this host. In this review, we first provide general information about the E. coli host and compare it with other hosts. In the next step, we describe the factors involved in the expression of the recombinant proteins in E. coli. Successful expression of recombinant proteins in E. coli requires a complete elucidation of these factors. Here, the characteristics of each factor will be fully described, and this information can help to improve the heterologous expression of recombinant proteins in E. coli.

Physicochemical Characterization of a Recombinant eCG and Comparative Studies with PMSG Commercial Preparations

Equine chorionic gonadotropin (eCG) is a glycoprotein hormone widely used in timed artificial ovulation (TAI) and superovulation protocols to improve the reproductive performance in livestock. Until recently, the only eCG products available in the market for veterinary use consisted in partially purified preparations of pregnant mare serum gonadotropin (PMSG). Here, a bioactive recombinant eCG (reCG) produced in suspension CHO-K1 cells was purified employing different chromatographic methods (hydrophobic interaction chromatography and reverse-phase (RP)-HPLC) and compared with a RP-HPLC-purified PMSG. To gain insight into the structural and functional characteristics of reCG, a bioinformatics analysis was performed. An exhaustive characterization comprising the determination of the purity degree, aggregates and nicked forms through SDS-PAGE, RP-HPLC and SEC-HPLC was performed. Higher order structures were studied by fluorescence spectroscopy and SEC-HPLC. Isoforms profile were analyzed by isoelectric focusing. Glycosylation analysis was performed through pulsed amperometric detection and PNGase F treatment following SDS-PAGE and weak anion exchange-HPLC. Slight differences between the purified recombinant hormones were found. However, recombinant molecules and PMSG exhibited variations in the glycosylation pattern. In fact, differences in sialic acid content between two commercial preparations of PMSG were also obtained, which could lead to differences in their biological potency. These results show the importance of having a standardized production process, as occurs in a recombinant protein bioprocess. Besides, our results reflect the importance of the glycan moieties on eCG conformation and hence in its biological activity, preventing denaturing processes such as aggregation.

Penicillium chrysogenum as a fungal factory for feruloyl esterases

Plant biomass is a promising substrate for biorefinery, as well as a source of bioactive compounds, platform chemicals, and precursors with multiple industrial applications. These applications depend on the hydrolysis of its recalcitrant structure. However, the effective biological degradation of plant cell walls requires several enzymatic groups acting synergistically, and novel enzymes are needed in order to achieve profitable industrial hydrolysis processes. In the present work, a feruloyl esterase (FAE) activity screening of Penicillium spp. strains revealed a promising candidate (Penicillium rubens Wisconsin 54-1255; previously Penicillium chrysogenum), where two FAE-ORFs were identified and subsequently overexpressed. Enzyme extracts were analyzed, confirming the presence of FAE activity in the respective gene products (PrFaeA and PrFaeB). PrFaeB-enriched enzyme extracts were used to determine the FAE activity optima (pH 5.0 and 50-55 °C) and perform proteome analysis by means of MALDI-TOF/TOF mass spectrometry. The studies were completed with the determination of other lignocellulolytic activities, an untargeted metabolite analysis, and upscaled FAE production in stirred tank reactors. The findings described in this work present P. rubens as a promising lignocellulolytic enzyme producer. KEY POINTS: • Two Penicillium rubens ORFs were first confirmed to have feruloyl esterase activity. • Overexpression of the ORFs produced a novel P. rubens strain with improved activity. • The first in-depth proteomic study of a P. rubens lignocellulolytic extract is shown.

Analyzing protein posttranslational modifications using enzyme-catalyzed expressed protein ligation

Expressed protein ligation (EPL) allows for the attachment of a synthetic peptide into the N- or C-terminus of a recombinant protein fragment to generate a site-specifically modified protein with substantial yields for biochemical and biophysical studies. In this method, multiple posttranslational modifications (PTMs) can be incorporated into a synthetic peptide containing an N-terminal Cysteine, which selectively reacts with a protein C-terminal thioester to afford an amide bond formation. However, the requirement of a Cysteine at the ligation site can limit EPL's potential applications. Here, we describe a method called enzyme-catalyzed EPL, which uses subtiligase to ligate protein thioesters with Cysteine-free peptides. The procedure includes generating protein C-terminal thioester and peptide, performing the enzymatic EPL reaction, and purifying the protein ligation product. We exemplify this method by generating phospholipid phosphatase PTEN with site-specific phosphorylations installed onto its C-terminal tail for biochemical assays.

Effects of recombinant anti-lipopolysaccharide factor expressed by Pichia pastoris on the growth performance, immune response and disease resistance of Litopenaeusvannamei

The codon-optimized anti-lipopolysaccharide factor (ALF) sequence was introduced into pPICZαA vector and transformed into Pichia pastoris GS115. The recombinant ALF yeast supernatant (rALF-mix) was freeze-dried and evaluated as a feed additive for Litopenaeus vannamei. It was found by antibacterial activity test in vitro that the rALF-mix had antibacterial activity under different pH and temperature conditions. The 0, 0.00375%, 0.0075%, 0.015%, 0.03% and 0.06% of rALF-mix were added respectively to make the six experimental diets. After a 10-week feeding trial with shrimps (2.36 ± 0.02 g), it was found that the weight gain rate (WGR) and protein efficiency ratio (PER) of shrimp in the groups with 0.0075%, 0.015% and 0.03% of dietary rALF-mix supplementation were significantly higher than those in the control group (P < 0.05). Dietary rALF-mix supplementation significantly increased the total haemocyte count, respiratory burst, phagocytic activity, total anti-oxidative capacity (T-AOC), phenol oxidase activity, nitric oxide synthase activity, lysozyme (LYZ) activity, serum antibacterial capacity in the hemolymph and the T-AOC, LYZ in the hepatopancreas of shrimps (P < 0.05). The malondialdehyde contents in hemolymph and hepatopancreas were significantly decreased (P < 0.05). Meanwhile, the expression levels of toll, immune deficiency, heat shock protein 70, crustin and lipopolysaccharide-β-glucan binding protein in the gill of shrimps were significantly increased (P < 0.05). After the challenge test, it was showed that dietary rALF-mix supplementation significantly improved the resistance of L. vannamei to Vibrio parahaemolyticus (P < 0.05). In conclusion, the rALF-mix can be used as a functional feed additive to improve the growth, immunity and disease resistance of shrimp. Based on the quadratic regression analysis for WGR, the optimal supplemental level of rALF-mix in diet for shrimp was estimated to be 0.02813%.

Overexpressing CrePAPS Polyadenylate Activity Enhances Protein Translation and Accumulation in Chlamydomonas reinhardtii

The alga Chlamydomonas reinhardtii is a potential platform for recombinant protein expression in the future due to various advantages. Dozens of C. reinhardtii strains producing genetically engineered recombinant therapeutic protein have been reported. However, owing to extremely low protein expression efficiency, none have been applied for industrial purposes. Improving protein expression efficiency at the molecular level is, therefore, a priority. The 3'-end poly(A) tail of mRNAs is strongly correlated with mRNA transcription and protein translation efficiency. In this study, we identified a canonical C. reinhardtii poly(A) polymerase (CrePAPS), verified its polyadenylate activity, generated a series of overexpressing transformants, and performed proteomic analysis. Proteomic results demonstrated that overexpressing CrePAPS promoted ribosomal assembly and enhanced protein accumulation. The accelerated translation was further verified by increased crude and dissolved protein content detected by Kjeldahl and bicinchoninic acid (BCA) assay approaches. The findings provide a novel direction in which to exploit photosynthetic green algae as a recombinant protein expression platform.

Heterologous overexpression and preliminary antimicrobial activity test of salmocin M, a novel colicin M-like bacteriocin against Salmonella sp

Currently, it is extremely important to identify and describe new alternative compounds with potential antimicrobial properties. Since various natural biological systems are capable of producing active compounds with such properties, many of them have been the subject of intensive study. The aim of this work was to heterologously overexpress, purify and preliminarily investigate the antimicrobial activity of a novel bacteriocin found in Salmonella species. Overexpressed protein shows an amino acid structure homologous to the well-known colicin M and was never expressed previously in the E. coli platform. Purified salmocin M showed an inhibition spectrum against Salmonella and E. coli strains. To determine its potential as an antimicrobial agent for use in medicine or the food industry, preliminary antimicrobial tests against pathogenic bacteria were carried out. Our research demonstrates that bacteriocin can be produced efficiently in bacterial expression systems, which are one of the cheapest and the most popular platforms for recombinant protein production. Moreover, preliminary results of microbiological tests showed its activity against most of the bacterial strains in a dose-dependent manner.

Recombinant Protein Production and Purification of Insoluble Proteins

Proteins are synthesized in heterologous systems because of the impossibility to obtain satisfactory yields from natural sources. The efficient production of soluble and functional recombinant proteins is among the main goals in the biotechnological field. In this context, it is important to point out that under stress conditions, protein folding machinery is saturated and this promotes protein misfolding and, consequently, protein aggregation. Thus, the selection of the optimal expression organism and its growth conditions to minimize the formation of insoluble protein aggregates should be done according to the protein characteristics and downstream requirements. Escherichia coli is the most popular recombinant protein expression system despite the great development achieved so far by eukaryotic expression systems. Besides, other prokaryotic expression systems, such as lactic acid bacteria and psychrophilic bacteria, are gaining interest in this field. However, it is worth mentioning that prokaryotic expression system poses, in many cases, severe restrictions for a successful heterologous protein production. Thus, eukaryotic systems such as mammalian cells, insect cells, yeast, filamentous fungus, and microalgae are an interesting alternative for the production of these difficult-to-express proteins.

Microbial protein cell factories fight back?

The biopharmaceutical market is growing faster than ever, with two production systems competing for market dominance: mammalian cells and microorganisms. In recent years, based on the rise of antibody-based therapies, new biotherapeutic approvals have favored mammalian hosts. However, not only has extensive research elevated our understanding of microbes to new levels, but emerging therapeutic molecules also facilitate their use; thus, is it time for microbes to fight back? In this review, we answer this timely question by cross-comparing four microbial production hosts and examining the innovations made to both their secretion and post-translational modification (PTM) capabilities. Furthermore, we discuss the impact of tools, such as omics and systems biology, as well as alternative production systems and emerging biotherapeutics.

The Potential of Metalloproteinase-9 Administration to Accelerate Mammary Involution and Boost the Immune System at Dry-Off

Simple Summary

The cow dry period is a critical period presenting a high risk of contracting intramammary infections. Active molecules to boost the innate immunity of the mammary gland and increase infection resilience could be decisive for the milking performance of dairy cows in the next lactation. Metalloproteinase-9 is a protein with a relevant role in facilitating the immune function and activating the regeneration of the mammary gland. The focus of this study was to test the role of the infusion of a recombinant version of metalloproteinase 9 at cow dry off, showing, contrary to expectations, that it is not able to enhance the innate immunity nor to improve the involution and regeneration of the mammary gland.

Abstract

The dry period is decisive for the milking performance of dairy cows. The promptness of mammary gland involution at dry-off affects not only the productivity in the next lactation, but also the risk of new intra-mammary infections since it is closely related with the activity of the immune system. Matrix metalloproteinase-9 (MMP-9) is an enzyme present in the mammary gland and has an active role during involution by disrupting the extracellular matrix, mediating cell survival and the recruitment of immune cells. The objective of this study was to determine the potential of exogenous administration of a soluble and recombinant version of a truncated MMP-9 (rtMMP-9) to accelerate mammary involution and boost the immune system at dry-off, avoiding the use of antibiotics. Twelve Holstein cows were dried abruptly, and two quarters of each cow received an intra-mammary infusion of either soluble rtMMP-9 or a positive control based on immunostimulant inclusion bodies (IBs). The contralateral quarters were infused with saline solution as negative control. Samples of mammary secretion were collected during the week following dry-off to determine SCC, metalloproteinase activity, bovine serum albumin, lactoferrin, sodium, and potassium concentrations. The soluble form of rtMMP-9 increased endogenous metalloproteinase activity in the mammary gland compared with saline quarters but did not accelerate either the immune response or involution in comparison with control quarters. The results demonstrated that the strategy to increase the mammary gland immunocompetence by recombinant infusion of rtMMP-9 was unsuccessful.

Effects of alkaline protease on the production performance, egg quality, and cecal microbiota of hens during late laying period

This study investigated the effects of diet supplementation with alkaline protease (AKP) on the production performance, egg quality, and cecal microbiota of laying hens. A total of 720 Hy-Line Brown laying hens (60 weeks old) were divided into four groups with six replicates of 30 birds each. No AKP was added to the control diet, and the hens in the other three groups (Groups 1, 2, and 3) were fed the basal diet supplemented with AKP preparations at 3, 6, and 9 u/g of diet, respectively. Results showed that AKP supplementation significantly decreased the feed/egg ratio (p < 0.05). Compared with that of the control group, the eggshell strength of Group 1 was significantly increased (p < 0.05), and the egg yolk weight of Groups 1 and 3 was significantly increased (p < 0.05). Distinctive difference in cecal microbiota was observed between AKP and control groups, and the average values of microbial diversity was lower in the AKP group than in the control group. The relative abundance of Bacteroidetes and Firmicutes at the phylum level, Rikenellaceae, Lachnospiraceae, Lactobacillaceae, Erysipelotrichaceae, and Christensenellaceae at the family level, and Rikenellaceae_RC9_gut_Group, Lactobacillus, Romboutsia, Lachnoclostridium, and Blautia at the genus level in the AKP group changed significantly compared with that in the control group (p<0.05).

Trends and Applications of Omics Technologies to Functional Characterisation of Enzymes and Protein Metabolites Produced by Fungi

Identifying and adopting industrial applications for proteins and enzymes derived from fungi strains have been at the focal point of several studies in recent times. To facilitate such studies, it is necessary that advancements and innovation in mycological and molecular characterisation are concomitant. This review aims to provide a detailed overview of the necessary steps employed in both qualitative and quantitative research using the omics technologies that are pertinent to fungi characterisation. This stems from the understanding that data provided from the functional characterisation of fungi and their metabolites is important towards the techno-economic feasibility of large-scale production of biological products. The review further describes how the functional gaps left by genomics, internal transcribe spacer (ITS) regions are addressed by transcriptomics and the various techniques and platforms utilised, including quantitive reverse transcription polymerase chain reaction (RT-qPCR), hybridisation techniques, and RNA-seq, and the insights such data provide on the effect of environmental changes on fungal enzyme production from an expressional standpoint. The review also offers information on the many available bioinformatics tools of analysis necessary for the analysis of the overwhelming data synonymous with the omics approach to fungal characterisation.

The Enzymatic Digestion of Pomaces From Some Fruits for Value-Added Feed Applications in Animal Production

With the noticed steady increase of global demand for animal proteins coupled with the current farming practices falling short in fulfilling the requested quantities, more attention is being paid for means and methods intended to maximize every available agricultural-resource in a highly sustainable fashion to address the above growing gap between production and consumers' demand. Within this regard, considerable efforts are being invested either in identifying new animal feed ingredients or maximizing the utilization of already established ones. The public preference and awareness of the importance of using waste products generated by fruit-dependent industries (juice, jams, spirits, etc.) has improved substantially in recent years where a genuine interest of using the above waste(s) in meaningful applications is solidifying and optimization-efforts are being pursued diligently. While many of the earlier reported usages of fruit pomaces as feedstuffs suggested the possibility of using minimally processed raw materials alone, the availability of exogenous digestive and bio-conversion enzymes is promising to take such applications to new un-matched levels. This review will discuss some efforts and practices using exogenous enzymes to enhance fruit pomaces quality as feed components as well as their nutrients' accessibility for poultry and swine production purposes. The review will also highlight efforts deployed to adopt numerous naturally derived and environmentally friendly catalytic agents for sustainable future feed applications and animal farming-practices.

Wolffia arrhiza as a promising producer of recombinant hirudin

The production of recombinant proteins in transgenic plants is becoming an increasingly serious alternative to classical biopharming methods as knowledge about this process grows. Wolffia arrhiza, an aquatic plant unique in its anatomy, is a promising expression system that can grow in submerged culture in bioreactors. In our study 8550 explants were subjected to Agrobacterium-mediated transformation, and 41 independent hygromycin-resistant Wolffia lines were obtained, with the transformation efficiency of 0.48%. 40 of them contained the hirudin-1 gene (codon-optimized for expression in plants) and were independent lines of nuclear-transformed Wolffia, the transgenic insertion has been confirmed by PCR and Southern blot analysis. We have analyzed the accumulation of the target protein and its expression has been proven in three transgenic lines. The maximum accumulation of recombinant hirudin was 0.02% of the total soluble protein, which corresponds to 775.5 ± 111.9 ng g^-1 of fresh weight of the plant. The results will be used in research on the development of an expression system based on Wolffia plants for the production of hirudin and other recombinant pharmaceutical proteins.

Soluble expression, purification, and secondary structure determination of human MESP1 transcription factor

Transcription factor MESP1 is a crucial factor regulating cardiac, hematopoietic, and skeletal myogenic development. Besides, it also contributes to the generation of functional cardiomyocytes. Here, we report the soluble expression and purification of the full-length human MESP1 protein from the heterologous system, which can be delivered into the target mammalian cells. To generate this biological macromolecule, we cloned its codon-optimized gene sequence fused to a nuclear localization sequence, a cell-penetrating peptide, and a His-tag into the protein expression vector and expressed in the bacterial system (E. coli strain BL21(DE3)). Subsequently, we have screened and identified the optimal expression parameters to obtain this recombinant fusion protein in soluble form from E. coli and examined its expression concerning the placement of fusion tags at either terminal. Further, we have purified this recombinant fusion protein to homogeneity under native conditions. Notably, this purified fusion protein has maintained its secondary structure after purification, primarily comprising α-helices and random coils. This molecular tool can potentially replace its genetic and viral forms in the cardiac reprogramming of fibroblasts to induce a cardiac transcriptional profile in an integration-free manner and elucidating its role in various biological processes and diseases. KEY POINTS: • Screening of the suitable gene construct was performed and identified. • Screening of optimal expression conditions was performed and identified. • Native purification of recombinant human MESP1 protein from E. coli was performed. • Recombinant MESP1 protein has retained its secondary structure after purification.

Generation and use of recombinant gonadotropins in fish

Understanding the differential roles of the pituitary gonadotropins Fsh and Lh in gonad maturation is crucial for a successful manipulation of the reproductive process in fish, and requires species-specific tools and appropriate active hormones. With the increasing availability of fish cDNAs coding for gonadotropin subunits, the production of recombinant hormones in heterologous systems has gradually substituted the approach of isolating native hormones. These recombinant hormones can be continually produced without depending on the fish as starting material and no cross-contamination with other pituitary glycoproteins is assured. Recombinant gonadotropins should be produced in eukaryotic cells, which have glycosylation capacity, but this post-translational modification varies greatly depending on the cell system, influencing hormone activity and stability. The production of recombinant gonadotropin beta-subunits to be used as antigens for antibody production has allowed the development of immunoassays for quantification of gonadotropins in some fish species. The administration in vivo of dimeric homologous recombinant gonadotropins has been used in basic studies and as a biotechnological approach to induce gametogenesis. In addition, gene-based therapies using somatic transfer of the gonadotropin genes have been tested as an alternative for hormone delivery in vivo. In summary, the use of homologous hormonal treatments can open new strategies in aquaculture to solve reproductive problems or develop out-of-season breeding programs.

[Equine chorionic gonadotrophin: Biology and veterinary use]

The pituitary gonadotrophins follicle-stimulating hormone (FSH) and luteinizing hormone (LH) play a prominent role in the control of gonadal functions. Therefore, their use in the treatment of fertility disorders (e. g. anovulatory anestrus) as well as in biotechnology (e. g. superovulation, hormone programs for cycle synchronization) is of substantial interest. Preparations of FSH or LH are relatively expensive due to the laborious extraction from pituitary tissue and are therefore reserved for special indications. In primates and equids, the chorionic epithelium expresses an LH-like molecule (chorionic gonadotrophin, CG). Equine CG (eCG) selectively binds to LH receptors in equids. In all other domestic mammalian species, equine CG (eCG) shows an extraordinarily high FSH activity in addition to its LH activity ("dual activity"). Since its market launch, this has therefore gained considerable importance as a comparatively inexpensive FSH analogue, mainly for use in ruminants and pigs. In contrast to the human CG (hCG), which may be isolated non-invasively from the urine of pregnant women and is widely used as LH analogue, eCG must be extracted from the blood of pregnant donor mares, as eCG concentrations in urine are only minimal. Following reports of deaths and suffering of donor mares associated with eCG collection in South American settings, the current practice of eCG production has given rise to increasing public criticism. This has recently led to calls for a general production ban. Primary aim of this review is therefore to summarize the current state of knowledge concerning the properties and biology of this molecule, which is also highly interesting from the point of view of basic science.

Controlled delivery of follicle-stimulating hormone in cattle

Embryo transfer in cattle is a key issue requiring in vivo production of several mature follicles as opposed to the normal production of only one. In vivo produced embryos can then be transferred to recipient cows for gestation to occur. To obtain a large number of transferable embryos, the superovulation step is crucial. To allow the growth of ovarian follicles, the most commonly used protocol consists of 2 intramuscular injections per day over 4 days of a saline solution of the follicle-stimulating hormone. To reduce workload, technical errors in the injected dose and animal stress, different strategies have been investigated to sustain the release of this hormone over 4 days in 1 or 2 injections. This review introduces the physicochemical properties of the follicle-stimulating hormone and discusses the limitations of marketed products and all the research that has been conducted to overcome these limitations. In particular, the field of subcutaneous administrations, the development of new formulations such as viscous solutions, implants and microspheres and the modification of the structure of the follicle-stimulating hormone are overviewed and discussed.

Effects of Exogenous Glucoamylase Enzymes Alone or in Combination with a Neutral Protease on Apparent Total Tract Digestibility and Feces D-Lactate in Crossbred Angus Bulls Fed a Ration Rich in Rolled Corn

Simple Summary

Dietary enzyme supplementation, as a feed additive, has been well adopted in monogastric production to increase feed efficiency. However, in ruminants, considerably fewer studies have been done and fewer, if any, commercial enzymes have been adopted as a feeding strategy. Feedlot cattle are commonly fed high-starch diets, with varying starch digestibilities depending on type of grain, and degree of grain processing. Improvement in starch digestibility in low processed grain diets will undoubtedly warrant economic benefits to feedlot producers and reduce environmental impact of intensive beef production. In this study, we have shown that dietary glucoamylase supplementation improved 7 to 13% apparent digestibility of dry matter and starch in bulls fed rolled corn-based diets, suggesting that enzyme (glucoamylase) supplementation could be a promising strategy to improve starch efficiency for finishing beef cattle.

Abstract

The aim of this study was to evaluate the effect of two glucoamylases (GA) and the combination of one GA with a neutral protease on apparent total tract digestibility in beef bulls fed a total mixed ration (TMR) rich in rolled corn. Sixteen Angus beef bulls (266 ± 4.9 kg of initial BW, and 182 ± 1.7 d of age) were distributed in 4 blocks, each block consisted of 4 animals balanced by BW. The experimental design was a 4 × 4 Latin square (4 blocks and 4 periods, 2 w per period). Four treatments were tested; (1) control, (2) GA preparation from Trichoderma reesei (TrGA); (3) GA from Aspergillus fumigatus (AfuGA); (4) AfuGA in combination with a neutral protease from Bacillus amyloliquefaciens (BamPro). Apparent total tract digestibility and fecal D-lactate concentration were analyzed. Enzyme supplementation, regardless of enzyme type, increased apparent total tract digestibility of dry matter (from 66.7% to 73.1% ± 2.01), and starch (from 74.7% to 81.8% ± 2.25), without affecting feces D-lactate concentration. Irrespective of glucoamylase type, glucoamylase supplementation improved apparent digestibility of dry matter and starch, and the addition of a protease did not have additional benefits on nutrient digestibility.

Application of Genetically Engineered Pigs in Biomedical Research

Progress in genetic engineering over the past few decades has made it possible to develop methods that have led to the production of transgenic animals. The development of transgenesis has created new directions in research and possibilities for its practical application. Generating transgenic animal species is not only aimed towards accelerating traditional breeding programs and improving animal health and the quality of animal products for consumption but can also be used in biomedicine. Animal studies are conducted to develop models used in gene function and regulation research and the genetic determinants of certain human diseases. Another direction of research, described in this review, focuses on the use of transgenic animals as a source of high-quality biopharmaceuticals, such as recombinant proteins. The further aspect discussed is the use of genetically modified animals as a source of cells, tissues, and organs for transplantation into human recipients, i.e., xenotransplantation. Numerous studies have shown that the pig (Sus scrofa domestica) is the most suitable species both as a research model for human diseases and as an optimal organ donor for xenotransplantation. Short pregnancy, short generation interval, and high litter size make the production of transgenic pigs less time-consuming in comparison with other livestock species This review describes genetically modified pigs used for biomedical research and the future challenges and perspectives for the use of the swine animal models.

Recombinant Protein-Based Nanoparticles: Elucidating their Inflammatory Effects In Vivo and their Potential as a New Therapeutic Format

Bacterial inclusion bodies (IBs) are protein-based nanoparticles of a few hundred nanometers formed during recombinant protein production processes in different bacterial hosts. IBs contain active protein in a mechanically stable nanostructured format that has been broadly characterized, showing promising potential in different fields such as tissue engineering, protein replacement therapies, cancer, and biotechnology. For immunomodulatory purposes, however, the interference of the format immunogenic properties—intrinsic to IBs—with the specific effects of the therapeutic protein is still an uncovered gap. For that, active and inactive forms of the catalytic domain of a matrix metalloproteinase-9 (MMP-9 and mutMMP-9, respectively) have been produced as IBs and compared with the soluble form for dermal inflammatory effects in mmp9 knock-out mice. After protein injections in air-pouches in the mouse model, MMP-9 IBs induce local neutrophil recruitment and increase pro-inflammatory chemokine levels, lasting for at least two days, whereas the effects triggered by the soluble MMP-9 format fade out after 3 h. Interestingly, the IB intrinsic effects (mutMMP-9 IBs) do not last more than 24 h. Therefore, it may be concluded that IBs could be used for the delivery of therapeutic proteins, such as immunomodulating proteins while preserving their stability in the specific tissue and without triggering important unspecific inflammatory responses due to the protein format.

Robot Cookies - Plant Cell Packs as an Automated High-Throughput Screening Platform Based on Transient Expression

The high-throughput screening of recombinant protein expression is advantageous during early process development because it allows the identification of optimal expression constructs and process conditions. Simple screening platforms based on microtiter plates are available for microbes and animal cells, but this was not possible for plants until the development of plant cell packs (PCPs), also known as “cookies,” which provide a versatile and scalable screening tool for recombinant protein production. PCPs are prepared from plant cell suspension cultures by removing the medium and molding the biomass. PCPs can be cast into 96-well plates for high-throughput screening, but the manual handling effort currently limits the throughput to ∼500 samples per day. We have therefore integrated the PCP method with a fully automated laboratory liquid-handling station. The “robot cookies” can be prepared and infiltrated with Agrobacterium tumefaciens by centrifugation, minimizing operator handling and reducing the likelihood of errors during repeated runs, such as those required in a design of experiments approach. The accumulation of fluorescent protein in the cytosol, apoplast, endoplasmic reticulum or plastids is easily detected using an integrated plate reader, reducing the inter-experimental variation to <5%. We also developed a detergent-based chemical lysis method for protein extraction in a 96-well format, which was adapted for automated downstream processing using miniaturized columns allowing subsequent protein analysis. The new automated method reduces the costs of the platform to <0.5 € per PCP infiltration (a saving of >50%) and facilitates a five-fold increase in throughput to >2500 samples per day.

Cloning, expression and characterization of a novel alkaline serine protease gene from native Iranian Bacillus sp.; a producer of protease for use in livestock

The use of proteases in the last decade has been welcomed in livestock and poultry industries and has led to significant results such as improved feed conversion ratio, weight gain and increased growth performance. In the present study, isolation and identification of a novel alkaline protease from Iranian Bacillus species was performed in order to use in livestock feed. After primary isolation of bacteria from soil samples of rice fields and early detection of bacterial genus, the zymogram plate was performed for evaluation of production extracellular proteases. Of the 11 strains producing protease, one strain that produced more enzymes was selected to continue the work. Characterization of alkaline protease was done using specific enzyme assays. To confirm the genus of isolates as well as to identify the species close to, molecular analysis of 16S rRNA gene sequence was done. After that, bioinformatics analysis carried out in NCBI database for searching bacterial alkaline proteases gene sequences. The primer designed based on gene homology of close species for extraction of alkaline protease gene. The results showed that the enzyme extract had the highest activity at pH 9.0 and 50 °C. The 16S rRNA gene sequence was submitted for the strain called Bacillus sp. RAM on the NCBI site. According to the results of the phylogenetic tree, the bacterium was belonged to Bacillus genus and Bacillus sp. RAM was close to Thuringiensis C405. The isolated alkaline protease gene successfully cloned in pET28a and transferred to the expression host E.coli BL21. The expression of the protease gene was evaluated by SDS-PAGE electrophoresis. The induced recombinant cells expressed the protease and revealed molecular weight band of about 38 kDa. According to the enzyme properties, this alkaline protease can useful for application in animal industry.

A new approach to obtain pure and active proteins from Lactococcus lactis protein aggregates

The production of pure and soluble proteins is a complex, protein-dependent and time-consuming process, in particular for those prone-to-aggregate and/or difficult-to-purify. Although Escherichia coli is widely used for protein production, recombinant products must be co-purified through costly processes to remove lipopolysaccharide (LPS) and minimize adverse effects in the target organism. Interestingly, Lactococcus lactis, which does not contain LPS, could be a promising alternative for the production of relevant proteins. However, to date, there is no universal strategy to produce and purify any recombinant protein, being still a protein-specific process. In this context and considering that L. lactis is also able to form functional protein aggregates under overproduction conditions, we explored the use of these aggregates as an alternative source of soluble proteins. In this study, we developed a widely applicable and economically affordable protocol to extract functional proteins from these nanoclusters. For that, two model proteins were used: mammary serum amyloid A3 (M-SAA3) and metalloproteinase 9 (MMP-9), a difficult-to-purify and a prone-to-aggregate protein, respectively. The results show that it is possible to obtain highly pure, soluble, LPS-free and active recombinant proteins from L. lactis aggregates through a cost-effective and simple protocol with special relevance for difficult-to-purify or highly aggregated proteins.

Characterization of carp gonadotropins: Structure, annual profile, and carp and zebrafish pituitary topographic organization

Two gonadotropins, follicle stimulating hormone (FSH) and luteinizing hormone (LH), are important players in the hypothalamic-pituitary-gonadal axis of vertebrates. In the present work, we describe the construction of recombinant (r) common carp (Cyprinus carpio; c) FSH (rcFSH) and LH (rcLH) using the Pichia pastoris system, the generation of specific antibodies against their respective β subunits, and their use in the development and validation of specific ELISAs. We produced carp rLH and rFSH as single-chain polypeptides, wherein the GTH subunit α was joined with either cLHβ or cFSHβ mature protein-coding sequences to form a fusion gene that encodes a yoked polypeptide, in which the GTH β-subunit forms the N-terminal part and the α-subunit forms the C-terminal part. Competitive ELISAs were developed, using primary antibodies against rcLHβ or rcFSHβ, respectively, and rcLHβα or rcFSHβα for the standard curves. The standard curves for cLH paralleled those of pituitary extracts of the homologous fish and also those of other cyprinids species like the black carp (Mylopharyngodon piceus), goldfish (Carassius auratus), silver carp (Hypophthalmichthys molitrix), and grass carp (Ctenopharyngodon idella). We used the specific antibodies raised against cFSH and cLH to study the specific localization of the different GTH cells in the pituitary of carp and its taxonomic relative species - the zebrafish. Both FSH and LH cells are localized in the center of the proximal pars distalis enveloping both sides of the neurohypophysis. LH cells form a continuous population throughout the PPD, while FSH cells are more loosely distributed throughout the same area and form small aggregations. Marked annual changes were encountered in gonadosomatic index (GSI), follicle diameter, mRNA levels and protein levels of FSH and LH. From September to November, all fish had low GSI, and the ovary contained previtellogenic follicles. From December, the GSI level increased and remained high until March, the follicular diameter reached its maximum in January, where the ovary contained large fully grown follicles. Thereafter, spawning occurred through March and April and ended in May, and GSI level and follicle diameter increased again; and the ovary contained mid-vitellogenic follicles. LH pituitary content and mRNA levels were low at pre- and early vitellogenesis, increasing gradually during this process to reach a peak of LH mRNA levels in mid vitellogenic ovary and a peak of LH content in fully grown ovarian follicles. However, no significant change occurred in FSH pituitary content and mRNA levels in vitellogenic fish and in fish during final maturation stages. A dramatic difference was found in the total content of each gonadotropin in the pituitary, with higher LH than FSH. Moreover, follicle diameter was positively and significantly correlated with LH pituitary content and its transcript levels - but not with the pituitary content or mRNA levels of FSH. Taken together, these results indicate that in carp, LH alone is sufficient to regulate both vitellogenesis and final oocyte maturation while FSH may have another, yet undefined role.

Innovative drugs, chemicals, and enzymes within the animal production chain

The alarming number of recently reported human illnesses with bacterial infections resistant to multiple antibacterial agents has become a serious concern in recent years. This phenomenon is a core challenge for both the medical and animal health communities, since the use of antibiotics has formed the cornerstone of modern medicine for treating bacterial infections. The empirical benefits of using antibiotics to address animal health issues in animal agriculture (using therapeutic doses) and increasing the overall productivity of animals (using sub-therapeutic doses) are well established. The use of antibiotics to enhance profitability margins in the animal production industry is still practiced worldwide. Although many technical and economic reasons gave rise to these practices, the continued emergence of antimicrobial resistant bacteria is furthering the need to reduce the use of medically important antibiotics. This will require improving on-farm management and biosecurity practices, and the development of effective antibiotic alternatives that will reduce the dependence on antibiotics within the animal industry in the foreseeable future. A number of approaches are being closely scrutinized and optimized to achieve this goal, including the development of promising antibiotic alternatives to control bacterial virulence through quorum-sensing disruption, the use of synthetic polymers and nanoparticles, the exploitation of recombinant enzymes/proteins (such as glucose oxidases, alkaline phosphatases and proteases), and the use of phytochemicals. This review explores the most recent approaches within this context and provides a summary of practical mitigation strategies for the extensive use of antibiotics within the animal production chain in addition to several future challenges that need to be addressed.

Secreted protein extract analyses present the plant pathogen Alternaria alternata as a suitable industrial enzyme toolbox

Lignocellulosic plant biomass is the most abundant carbon source in the planet, which makes it a potential substrate for biorefinery. It consists of polysaccharides and other molecules with applications in pharmaceutical, food and feed, cosmetics, paper and textile industries. The exploitation of these resources requires the hydrolysis of the plant cell wall, which is a complex process. Aiming to discover novel fungal natural isolates with lignocellulolytic capacities, a screening for feruloyl esterase activity was performed in samples taken from different metal surfaces. An extracellular enzyme extract from the most promising candidate, the natural isolate Alternaria alternata PDA1, was analyzed. The feruloyl esterase activity of the enzyme extract was characterized, determining the pH and temperature optima (pH 5.0 and 55-60 °C, respectively), thermal stability and kinetic parameters, among others. Proteomic analyses derived from two-dimensional gels allowed the identification and classification of 97 protein spots from the extracellular proteome. Most of the identified proteins belonged to the carbohydrates metabolism group, particularly plant cell wall degradation. Enzymatic activities of the identified proteins (β-glucosidase, cellobiohydrolase, endoglucanase, β-xylosidase and xylanase) of the extract were also measured. These findings confirm A. alternata PDA1 as a promising lignocellulolytic enzyme producer.

SIGNIFICANCE

Although plant biomass is an abundant material that can be potentially utilized by several industries, the effective hydrolysis of the recalcitrant plant cell wall is not a straightforward process. As this hydrolysis occurs in nature relying almost solely on microbial enzymatic systems, it is reasonable to infer that further studies on lignocellulolytic enzymes will discover new sustainable industrial solutions. The results included in this paper provide a promising fungal candidate for biotechnological processes to obtain added value from plant byproducts and analogous substrates. Moreover, the proteomic analysis of the secretome of a natural isolate of Alternaria sp. grown in the presence of one of the most used vegetal substrates on the biofuels industry (sugar beet pulp) sheds light on the extracellular enzymatic machinery of this fungal plant pathogen, and can be potentially applied to developing new industrial enzymatic tools. This work is, to our knowledge, the first to analyze in depth the secreted enzyme extract of the plant pathogen Alternaria when grown on a lignocellulosic substrate, identifying its proteins by means of MALDI-TOF/TOF mass spectrometry and characterizing its feruloyl esterase, cellulase and xylanolytic activities.

Improving Biomaterials Imaging for Nanotechnology: Rapid Methods for Protein Localization at Ultrastructural Level

The preparation of biological samples for electron microscopy is material- and time-consuming because it is often based on long protocols that also may produce artifacts. Protein labeling for transmission electron microscopy (TEM) is such an example, taking several days. However, for protein-based nanotechnology, high resolution imaging techniques are unique and crucial tools for studying the spatial distribution of these molecules, either alone or as components of biomaterials. In this paper, we tested two new short methods of immunolocalization for TEM, and compared them with a standard protocol in qualitative and quantitative approaches by using four protein-based nanoparticles. We reported a significant increase of labeling per area of nanoparticle in both new methodologies (H = 19.811; p < 0.001) with all the model antigens tested: GFP (H = 22.115; p < 0.001), MMP-2 (H = 19.579; p < 0.001), MMP-9 (H = 7.567; p < 0.023), and IFN-γ (H = 62.110; p < 0.001). We also found that the most suitable protocol for labeling depends on the nanoparticle's tendency to aggregate. Moreover, the shorter methods reduce artifacts, time (by 30%), residues, and reagents hindering, losing, or altering antigens, and obtaining a significant increase of protein localization (of about 200%). Overall, this study makes a step forward in the development of optimized protocols for the nanoscale localization of peptides and proteins within new biomaterials.

Microbial phytase: Impact of advances in genetic engineering in revolutionizing its properties and applications

Phytases are enzymes that increase the availability of phosphorous in monogastric diet and reduces the anti-nutrition effect of phytate. This review highlights contributions of recombinant technology to phytase research during the last decade with specific emphasis on new generation phytases. Application of modern molecular tools and genetic engineering have aided the discovery of novel phytase genes, facilitated its commercial production and expanded its applications. In future, by adopting most recent gene improvement techniques, more efficient next generation phytases can be developed for specific applications.

Trends and Prospects of Plant Proteases in Therapeutics

The main function of proteases in any living organism is the cleavage of proteins resulting in the degradation of damaged, misfolded and potentially harmful proteins and therefore providing the cell with amino acids essential for the synthesis of new proteins. Besides this main function, proteases may play an important role as signal molecules and participate in numerous protein cascades to maintain the vital processes of an organism. Plant proteases are no exception to this rule. Moreover, in contrast to humanencoded enzymes, many plant proteases possess exceptional features such as higher stability, unique substrate specificity and a wide pH range for enzymatic activity. These valuable features make plant-derived proteolytic enzymes suitable for many biomedical applications, and furthermore, the plants can serve as factories for protein production. Plant proteases are already applied in the treatment of several pathological conditions in the human organism. Some of the enzymes possess antitumour, antibacterial and antifungal activity. The collagenolytic activity of plant proteases determines important medical applications such as the healing of wounds and burn debridement. Plant proteases may affect blood coagulation processes and can be applied in the treatment of digestive disorders. The present review summarizes recent advances and possible applications for plant proteases in biomedicine, and proposes further development of plant-derived proteolytic enzymes in the biotechnology and pharmaceutical industries.

Development of an antibiotic marker-free platform for heterologous protein production in Streptomyces

BACKGROUND

The industrial use of enzymes produced by microorganisms is continuously growing due to the need for sustainable solutions. Nevertheless, many of the plasmids used for recombinant production of proteins in bacteria are based on the use of antibiotic resistance genes as selection markers. The safety concerns and legal requirements surrounding the increased use of antibiotic resistance genes have made the development of new antibiotic-free approaches essential.

RESULTS

In this work, a system completely free of antibiotic resistance genes and useful for the production of high yields of proteins in Streptomyces is described. This system is based on the separation of the two components of the yefM/yoeBsl (antitoxin/toxin) operon; the toxin (yoeBsl) gene, responsible for host death, is integrated into the genome and the antitoxin gene (yefMsl), which inactivates the toxin, is located in the expression plasmid. To develop this system, the toxin gene was integrated into the genome of a strain lacking the complete operon, and the antibiotic resistance gene integrated along with the toxin was eliminated by Cre recombinase to generate a final host strain free of any antibiotic resistance marker. In the same way, the antibiotic resistance gene from the final expression plasmid was removed by Dre recombinase. The usefulness of this system was analysed by checking the production of two hydrolases from different Streptomyces. Production of both proteins, with potential industrial use, was high and stable over time after strain storage and after serial subcultures. These results support the robustness and stability of the positive selection system developed.

CONCLUSIONS

The total absence of antibiotic resistance genes makes this system a powerful tool for using Streptomyces as a host to produce proteins at the industrial level. This work is the first Streptomyces antibiotic marker-free system to be described. Graphical abstract Antibiotic marker-free platform for protein expression in Streptomyces. The antitoxin gene present in the expression plasmid counteracts the effect of the toxin gene in the genome. In absence of the expression plasmid, the toxin causes cell death ensuring that only plasmid-containing cells persist.