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.

An Alternative to Antibiotics: Selected Methods to Combat Zoonotic Foodborne Bacterial Infections.

Pathogenic bacteria contaminating food or animal feed cause serious economic losses in the health sector as well as is in the agriculture and food industry. The development of bacterial resistance due to the misuse of antibiotics and chemicals, especially in the farm industry, can bring dangerous effects for the global population therefore new safe biological antimicrobial solutions are urgently needed. In this paper, we investigate biological alternatives to antibiotics against foodborne pathogens. The most promising alternatives include antimicrobial proteins, bacteriophages, probiotics, and plant-based substances. Each described group of substances is efficient against specific foodborne bacteria and has a preferred use in an explicit application. The advantages and drawbacks of each method are outlined in the final section. Biological antibacterial solutions are usually easily degradable. In contrast to antibiotics or chemical/physical methods, they are also far more specific. When introducing new antibacterial methods it is crucial to check their safety and ability to induce resistance mechanisms. Moreover, it is important to assess its activity to inhibit or kill in viable but nonculturable cells (VBNC) state and biofilm forms. VBNC bacteria are considered a threat to public health and food safety due to their possibility of remaining viable and virulent. Biological alternatives to antibiotics complete the majority of the advantages needed for a safe and efficient antimicrobial product. However, further research is necessary to fully implement those solutions to the market.

Chloroplasts: state of research and practical applications of plastome sequencing.

MAIN CONCLUSION: This review presents origins, structure and expression of chloroplast genomes. It also describes their sequencing, analysis and modification, focusing on potential practical uses and biggest challenges of chloroplast genome modification. During the evolution of eukaryotes, cyanobacteria are believed to have merged with host heterotrophic cell. Afterward, most of cyanobacterial genes from cyanobacteria were transferred to cell nucleus or lost in the process of endosymbiosis. As a result of these changes, a primary plastid was established. Nowadays, plastid genome (plastome) is almost always circular, has a size of 100-200 kbp (120-160 in land plants), and harbors 100-120 highly conserved unique genes. Plastids have their own gene expression system, which is similar to one of their cyanobacterial ancestors. Two different polymerases, plastid-derived PEP and nucleus-derived NEP, participate in transcription. Translation is similar to the one observed in cyanobacteria, but it also utilizes protein translation factors and positive regulatory mRNA elements absent from bacteria. Plastoms play an important role in genetic transformation. Transgenes are introduced into them either via gene gun (in undamaged tissues) or polyethylene glycol treatment (when protoplasts are targeted). Antibiotic resistance markers are the most common tool used for selection of transformed plants. In recent years, plastome transformation emerged as a promising alternative to nuclear transformation because of (1) high yield of target protein, (2) removing the risk of outcrossing with weeds, (3) lack of silencing mechanisms, and (4) ability to engineer the entire metabolic pathways rather than single gene traits. Currently, the main directions of such research regard: developing efficient enzyme, vaccine antigen, and biopharmaceutical protein production methods in plant cells and improving crops by increasing their resistance to a wide array of biotic and abiotic stresses. Because of that, the detailed knowledge of plastome structure and mechanism of functioning started to play a major role.

Extraction and purification methods in downstream processing of plant-based recombinant proteins.

During the last two decades, the production of recombinant proteins in plant systems has been receiving increased attention. Currently, proteins are considered as the most important biopharmaceuticals. However, high costs and problems with scaling up the purification and isolation processes make the production of plant-based recombinant proteins a challenging task. This paper presents a summary of the information regarding the downstream processing in plant systems and provides a comprehensible overview of its key steps, such as extraction and purification. To highlight the recent progress, mainly new developments in the downstream technology have been chosen. Furthermore, besides most popular techniques, alternative methods have been described.