Engineering of Human Lactoferrin for Improved Anticancer Activity

Protease-digested lactoferrin fragments often exhibit improved therapeutic properties. However, there are limited studies investigating the anticancer properties of these fragments. The fragment with improved anticancer activities is an attractive alternative to chemotherapeutic drugs-presenting severe side effects. Herein, we report the isolation and characterization of recombinant engineered-lactoferrin (rtHLF4), exhibiting up to 100-fold improved anticancer activity compared to the full-length lactoferrin (flHLF). Further, rtHLF4 exerts its anticancer effect in a shorter duration. Through transcriptomic analysis of various cancer biomarkers, rtHLF4 was found to upregulate various pro-apoptotic markers and downregulate signaling proteins involved in angiogenesis and metastasis. We further determined that rtHLF4 showed no hemolytic activity at high concentrations. We believe that this anticancer protein can be further developed as a cancer treatment.

Elucidation of Gram-Positive Bacterial Iron(III) Reduction for Kaolinite Clay Refinement

Recently, microbial-based iron reduction has been considered as a viable alternative to typical chemical-based treatments. The iron reduction is an important process in kaolin refining, where iron-bearing impurities in kaolin clay affects the whiteness, refractory properties, and its commercial value. In recent years, Gram-negative bacteria has been in the center stage of iron reduction research, whereas little is known about the potential use of Gram-positive bacteria to refine kaolin clay. In this study, we investigated the ferric reducing capabilities of five microbes by manipulating the microbial growth conditions. Out of the five, we discovered that Bacillus cereus and Staphylococcus aureus outperformed the other microbes under nitrogen-rich media. Through the biochemical changes and the microbial behavior, we mapped the hypothetical pathway leading to the iron reduction cellular properties, and found that the iron reduction properties of these Gram-positive bacteria rely heavily on the media composition. The media composition results in increased basification of the media that is a prerequisite for the cellular reduction of ferric ions. Further, these changes impact the formation of biofilm, suggesting that the cellular interaction for the iron(III)oxide reduction is not solely reliant on the formation of biofilms. This article reveals the potential development of Gram-positive microbes in facilitating the microbial-based removal of metal contaminants from clays or ores. Further studies to elucidate the corresponding pathways would be crucial for the further development of the field.

The potential of lactoferrin, ovotransferrin and lysozyme as antiviral and immune-modulating agents in COVID-19

Coronavirus disease 2019 (COVID-19), caused by SARS coronavirus 2 (SARS-CoV-2), is spreading rapidly with no established effective treatments. While most cases are mild, others experience uncontrolled inflammatory responses with oxidative stress, dysregulation of iron and coagulation as features. Lactoferrin, ovotransferrin and lysozyme are abundant, safe antimicrobials that have wide antiviral as well as immunomodulatory properties. In particular, lactoferrin restores iron homeostasis and inhibits replication of SARS-CoV, which is closely related to SARS-CoV-2. Ovotransferrin has antiviral peptides and activities that are shared with lactoferrin. Both lactoferrin and lysozyme are ‘immune sensing’ as they may stimulate immune responses or resolve inflammation. Mechanisms by which these antimicrobials may treat or prevent COVID-19, as well as sources and forms of these, are reviewed.

Magnetic Immobilization of Pichia pastoris Cells for the Production of Recombinant Human Serum Albumin

Magnetic immobilization as a novel technique was used to immobilize recombinant Pichia pastoris (GS115 Albumin) cells to produce human serum albumin (HSA). In this regard, magnetic nanoparticles (MNPs) coated with amino propyl triethoxy silane (APTES) were synthesized. P. pastoris cells were decorated with MNPs via nonspecific interactions. Decorated cells were magneto-responsible and easily harvested by applying an external magnetic field. The efficiency of magnetic immobilization (E_i) for cell removal was in direct relation with the MNP concentration and time of exposure to the magnetic field. By increasing the nanoparticles concentration, cells were harvested in a shorter period. Complete cell removal (E_i ≈ 100) was achieved in ≥0.5 mg/mL of MNPs in just 30 s. HSA is produced in an extremely high cell density (OD ~20) and it is the first time that magnetic immobilization was successfully employed for harvesting such a thick cell suspension. After 5 days of induction the cells, which were immobilized with 0.25 to 1 mg/mL of nanoparticles, showed an increased potency for recombinant HSA production. The largest increase in HSA production (38.1%) was achieved in the cells that were immobilized with 0.5 mg/mL of nanoparticles. These results can be considered as a novel approach for further developments in the P. pastoris-based system.

A 90-day subchronic toxicology screen of genetically modified rice Lac-3 and its effects on the gut microbiota in Sprague-Dawley rats

A 90-day subchronic toxicology screen of genetically modified (GM) rice Lac-3 expressing human lactoferrin (hLF) and its effects on the gut microbiota were studied in comparison to non-GM rice fed to Sprague-Dawley (SD) rats. Three different dietary concentrations (17.5%, 35% and 70%, w/w) of the GM rice or its corresponding non-GM rice were used. Additionally, the phylotypes of gut microbiota in the control group, the 70% GM rice diet group and the 70% non-GM rice diet group on day 90 were determined by 16S rRNA sequencing. The results of the 90-day subchronic feeding study demonstrated that the GM rice Lac-3 containing human lactoferrin (LF) gene is considered as safe as the non-GM rice. The results of bacterial 16S rRNA sequencing showed that the structure of gut microbiota in the 70% GM group slightly changed when compared with the control group and the 70% non-GM group. There were no significant differences in the microbiota diversity among the three groups.

Engineered commensal microbes for diet-mediated colorectal-cancer chemoprevention

Chemoprevention-the use of medication to prevent cancer-can be augmented by the consumption of produce enriched with natural metabolites. However, chemopreventive metabolites are typically inactive and have low bioavailability and poor host absorption. Here, we show that engineered commensal microbes can prevent carcinogenesis and promote the regression of colorectal cancer through a cruciferous vegetable diet. The engineered commensal Escherichia coli bound specifically to the heparan sulphate proteoglycan on colorectal cancer cells and secreted the enzyme myrosinase to transform host-ingested glucosinolates-natural components of cruciferous vegetables-to sulphoraphane, an organic small molecule with known anticancer activity. The engineered microbes coupled with glucosinolates resulted in >95% proliferation inhibition of murine, human and colorectal adenocarcinoma cell lines in vitro. We also show that murine models of colorectal carcinoma fed with the engineered microbes and the cruciferous vegetable diet displayed significant tumour regression and reduced tumour occurrence.

High-Level Expression of Recombinant Bovine Lactoferrin in Pichia pastoris with Antimicrobial Activity

In this study, bovine lactoferrin (bLf), an iron-binding glycoprotein considered an important nutraceutical protein because of its several properties, was expressed in Pichia pastoris KM71-H under AOX1 promoter control, using pJ902 as the recombinant plasmid. Dot blotting analysis revealed the expression of recombinant bovine lactoferrin (rbLf) in Pichia pastoris. After Bach fermentation and purification by molecular exclusion, we obtained an expression yield of 3.5 g/L of rbLf. rbLf and predominantly pepsin-digested rbLf (rbLfcin) demonstrated antibacterial activity against Escherichia coli (E. coli) BL21DE3, Staphylococcus aureus (S. aureus) FRI137, and, in a smaller percentage, Pseudomonas aeruginosa (Ps. Aeruginosa) ATCC 27833. The successful expression and characterization of functional rbLf expressed in Pichia pastoris opens a prospect for the development of natural antimicrobial agents produced recombinantly.