Bacteriocin Occurrence and Activity in Escherichia coli Isolated from Bovines and Wastewater

Beyond Conventional Meat Preservation: Saddling the Control of Bacteriocin and Lactic Acid Bacteria for Clean Label and Functional Meat Products

Advancements in food science and technology have paved the way for the development of natural antimicrobial compounds to ensure the safety and quality of meat and meat products. Among these compounds, bacteriocin produced by lactic acid bacteria has gained considerable scientific attention for its ability to preserve the healthy properties of meat while preventing spoilage. This natural preservative is seen as a pioneering tool and a potent alternative to chemical preservatives and heat treatment, which can have harmful effects on the nutritional and sensory qualities of meat. Bacteriocin produced by lactic acid bacteria can be used in various forms, including as starter/protective cultures for fermented meats, purified or partially purified forms, loaded in active films/coatings, or established in encapsulate systems. This review delves into the downstream purification schemes of LAB bacteriocin, the elucidation of their characteristics, and their modes of action. Additionally, the application of LAB bacteriocins in meat and meat products is examined in detail. Overall, the use of LAB bacteriocins holds immense potential to inspire innovation in the meat industry, reducing the dependence on harmful chemical additives and minimizing the adverse effects of heat treatment on nutritional and sensory qualities. This review provides a comprehensive understanding of the potential of bacteriocin produced by lactic acid bacteria as a natural and effective meat preservative.

Turbidimetric bioassays: A solution to antimicrobial activity detection in asymptomatic bacteriuria isolates against uropathogenic Escherichia coli

Traditional bacteriocin screening methods often face limitations due to diffusion-related challenges in agar matrices, which can prevent the peptides from reaching their target organism. Turbidimetric techniques offer a solution to these issues, eliminating diffusion-related problems and providing an initial quantification of bacteriocin efficacy in producer organisms. This study involved screening the cell-free supernatant (CFS) from eight uncharacterized asymptomatic bacteriuria (ABU) isolates and Escherichia coli 83972 for antimicrobial activity against clinical uropathogenic E. coli (UPEC) strains using turbidimetric growth methods. ABU isolates exhibiting activity against five or more UPEC strains were further characterized (PUTS 37, PUTS 58, PUTS 59, S-07-4, and SK-106-1). The inhibition of the CFS by proteinase K suggested that the antimicrobial activity was proteinaceous in nature, potentially bacteriocins. The activity of E. coli PUTS 58 and SK-106-1 was enhanced in an artificial urine medium, with both inhibiting all eight UPECs. A putative microcin H47 operon was identified in E. coli SK-106-1, along with a previously identified microcin V and colicin E7 in E. coli PUTS 37 and PUTS 58, respectively. These findings indicate that ABU bacteriocin-producers could serve as viable prophylactics and therapeutics in the face of increasing antibiotic resistance among uropathogens.

Tracing the Evolutionary Pathways of Serogroup O78 Avian Pathogenic Escherichia coli

Avian pathogenic E. coli (APEC) causes severe economic losses in the poultry industry, and O78 serogroup APEC strains are prevalent in chickens. In this study, we aimed to understand the evolutionary pathways and relationships between O78 APEC and other E. coli strains. To trace these evolutionary pathways, we classified 3101 E. coli strains into 306 subgenotypes according to the numbers and types of single nucleotide polymorphisms (RST0 to RST63-1) relative to the consensus sequence (RST0) of the RNA polymerase beta subunit gene and performed network analysis. The E. coli strains showed four apparently different evolutionary pathways (I-1, I-2, I-3, and II). The thirty-two Korean O78 APEC strains tested in this study were classified into RST4-4 (45.2%), RST3-1 (32.3%), RST21-1 (12.9%), RST4-5 (3.2%), RST5-1 (3.2%), and RST12-6 (3.2%), and all RSTs except RST21-1 (I-2) may have evolved through the same evolutionary pathway (I-1). A comparative genomic study revealed the highest relatedness between O78 strains of the same RST in terms of genome sequence coverage/identity and the spacer sequences of CRISPRs. The early-appearing RST3-1 and RST4-4 prevalence among O78 APEC strains may reflect the early settlement of O78 E. coli in chickens, after which these bacteria accumulated virulence and antibiotic resistance genes to become APEC strains. The zoonotic risk of the conventional O78 APEC strains is low at present, but the appearance of genetically distinct and multiple virulence gene-bearing RST21-1 O78 APEC strains may alert us to a need to evaluate their virulence in chickens as well as their zoonotic risk.

Bacteriocin-Producing Escherichia coli Q5 and C41 with Potential Probiotic Properties: In Silico, In Vitro, and In Vivo Studies

Commensal bacteriocin-producing Escherichia coli are of interest for possible use as probiotics to selectively control the spread of pathogenic bacteria. Here, we evaluated the biosafety and efficacy of two new bacteriocin-producing E. coli strains, Q5 (VKM B-3706D) and C41 (VKM B-3707D), isolated from healthy farm animals. The genomes of both strains were sequenced, and genes responsible for the antagonistic and colonization abilities of each strain were identified. In vitro studies have shown that both strains were medium-adhesive and demonstrated antagonistic activity against most enteropathogens tested. Oral administration of 5 × 108 to 5 × 1010 colony-forming units of both strains to rats with drinking water did not cause any disease symptoms or side effects. Short-term (5 days) oral administration of both strains protected rats from colonization and pathogenic effects of a toxigenic beta-lactam-resistant strain of E. coli C55 and helped preserve intestinal homeostasis. Taken together, these in silico, in vitro, and in vivo data indicate that both strains (and especially E. coli Q5) can be potentially used for the prevention of colibacillosis in farm animals.

Molecular and Genetic Characterization of Colicinogenic Escherichia coli Strains Active against Shiga Toxin-Producing Escherichia coli O157:H7

The objective of this work was to molecularly and genotypically characterize and test the inhibitory activity of six colicinogenic Escherichia coli strains (ColEc) and their partially purified colicins against STEC O157:H7 isolated from clinical human cases. Inhibition tests demonstrated the activity of these strains and their colicins against STEC O157:H7. By PCR it was possible to detect colicins Ia, E7, and B and microcins M, H47, C7, and J25. By genome sequencing of two selected ColEc strains, it was possible to identify additional colicins such as E1 and Ib. No genes coding for stx1 and stx2 were detected after analyzing the genome sequence. The inhibitory activity of ColEc against STEC O157:H7 used as an indicator showed that colicins are potent growth inhibitors of E. coli O157:H7, being a potential alternative to reduce the presence of pathogens of public health relevance.

Colicins and Microcins Produced by Enterobacteriaceae: Characterization, Mode of Action, and Putative Applications

Enterobacteriaceae are widely present in many environments related to humans, including the human body and the food that they consume, from both plant or animal origin. Hence, they are considered relevant members of the gastrointestinal tract microbiota. On the other hand, these bacteria are also recognized as putative pathogens, able to impair human health and, in food, they are considered indicators for the microbiological quality and hygiene status of a production process. Nevertheless, beneficial properties have also been associated with Enterobacteriaceae, such as the ability to synthesize peptides and proteins, which can have a role in the structure of microbial communities. Among these antimicrobial molecules, those with higher molecular mass are called colicins, while those with lower molecular mass are named microcins. In recent years, some studies show an emphasis on molecules that can help control the development of pathogens. However, not enough data are available on this subject, especially related to microcins. Hence, this review gathers and summarizes current knowledge on colicins and microcins, potential usage in the treatment of pathogen-associated diseases and cancer, as well as putative applications in food biotechnology.

Bacteriocin-Producing Escherichia coli Isolated from the Gastrointestinal Tract of Farm Animals: Prevalence, Molecular Characterization and Potential for Application

Due to the spread of antibiotic-resistant bacteria, new alternatives to antibiotics and ways to prevent infections are being sought. Bacteriocin-producing bacteria are therefore attracting attention due to their probiotic potential as a safe alternative to antimicrobial drugs. The aim of this work was to determine the prevalence of bacteriocin-encoded genes among Escherichia coli strains from healthy farm animals and to characterize the presence of virulence-associated genes, the possibility of prophage induction, and hemolytic and bacterial antagonistic activity of the bacteriocin-producing E. coli in order to reveal their potential for application. It was found that 17 of 72 E. coli strains (23.6%) produced bacteriocins. Among them, 18 out of 30 bacteriocin genes were detected: the most prevalent genes were those for microcin M (58.8%), colicin E1 (52.9%), and colicin M (35.3%). Colicin Ia (29.4%), colicin E9, colicin Ib, colicin B (23.5%), and colicin E9 (17.7%) genes were also frequent, while the prevalence of genes encoding microcins V, B17, and H47 and colicins E3, K, N, U, Y, 5, and 10 did not exceed 11.8%. At least two different bacteriocin genes were detected in all 17 bacteriocinogenic strains; the highest number of different bacteriocin genes detected in one strain was seven genes. E. coli strains with combinations of colicin E1 and E or microcin M and colicin E1 genes were more prevalent than others (17.7%). Among the 17 bacteriocin-producing E. coli strains, 5.9% were hemolytic, 47.1% contained prophages, and 58.8% carried genes encoding toxins. Cell-free supernatants of bacteriocin-producing strains were shown to inhibit the growth of pathogenic E. coli strains belonging to the APEC, STEC, and ETEC pathotypes. Thus, among the studied bacteriocin-producing E. coli isolated from the gastrointestinal tract of farm animals, three strains with high antagonistic bacterial activity and the absence of pathogenicity genes, prophages, and hemolytic activity were identified and therefore have potential for application.

Microbial Antagonism in Food-Enrichment Culture: Inhibition of Shiga Toxin-Producing Escherichia coli and Shigella Species

Bacterial pathogens, such as Shiga toxin-producing Escherichia coli (STEC) and Shigella spp., are important causes of foodborne illness internationally. Recovery of these organisms from foods is critical for food safety investigations to support attribution of illnesses to specific food commodities; however, isolation of bacterial cultures can be challenging. Methods for the isolation of STEC and Shigella spp. from foods typically require enrichment to amplify target organisms to detectable levels. Yet, during enrichment, target organisms can be outcompeted by other bacteria in food matrices due to faster growth rates, or through production of antimicrobial agents such as bacteriocins or bacteriophages. The purpose of this study was to evaluate the occurrence of Shigella and STEC inhibitors produced by food microbiota. The production of antimicrobial compounds in cell-free extracts from 200 bacterial strains and 332 food-enrichment broths was assessed. Cell-free extracts produced by 23 (11.5%) of the strains tested inhibited growth of at least one of the five Shigella and seven STEC indicator strains used in this study. Of the 332 enrichment broths tested, cell-free extracts from 25 (7.5%) samples inhibited growth of at least one of the indicator strains tested. Inhibition was most commonly associated with E. coli recovered from meat products. Most of the inhibiting compounds were determined to be proteinaceous (34 of the 48 positive samples, 71%; including 17 strains, 17 foods) based on inactivation by proteolytic enzymes, indicating presence of bacteriocins. The cell-free extracts from 13 samples (27%, eight strains, five foods) were determined to contain bacteriophages based on the observation of plaques in diluted extracts and/or resistance to proteolytic enzymes. These results indicate that the production of inhibitors by food microbiota may be an important challenge for the recovery of foodborne pathogens, particularly for Shigella sonnei. The performance of enrichment media for recovery of Shigella and STEC could be improved by mitigating the impact of inhibitors produced by food microbiota during the enrichment process.

The Potential of Probiotics to Eradicate Gut Carriage of Pathogenic or Antimicrobial-Resistant Enterobacterales

Probiotic supplements have been used to decrease the gut carriage of antimicrobial-resistant Enterobacterales through changes in the microbiota and metabolomes, nutrition competition, and the secretion of antimicrobial proteins. Many probiotics have shown Enterobacterales-inhibiting effects ex vivo and in vivo. In livestock, probiotics have been widely used to eradicate colon or environmental antimicrobial-resistant Enterobacterales colonization with promising efficacy for many years by oral supplementation, in ovo use, or as environmental disinfectants. In humans, probiotics have been used as oral supplements for infants to decease potential gut pathogenic Enterobacterales, and probiotic mixtures, especially, have exhibited positive results. In contrast to the beneficial effects in infants, for adults, probiotic supplements might decrease potentially pathogenic Enterobacterales, but they fail to completely eradicate them in the gut. However, there are several ways to improve the effects of probiotics, including the discovery of probiotics with gut-protection ability and antimicrobial effects, the modification of delivery methods, and the discovery of engineered probiotics. The search for multifunctional probiotics and synbiotics could render the eradication of “bad” Enterobacterales in the human gut via probiotic administration achievable in the future.

Comparative genomics analysis of Pediococcus acidilactici species

Pediococcus acidilactici is a reliable bacteriocin producer and a promising probiotic species with wide application in the food and health industry. However, the underlying genetic features of this species have not been analyzed. In this study, we performed a comprehensive comparative genomic analysis of 41 P. acidilactici strains from various ecological niches. The bacteriocin production of 41 strains were predicted and three kinds of bacteriocin encoding genes were identified in 11 P. acidilactici strains, namely pediocin PA-1, enterolysin A, and colicin-B. Moreover, whole-genome analysis showed a high genetic diversity within the population, mainly related to a large proportion of variable genomes, mobile elements, and hypothetical genes obtained through horizontal gene transfer. In addition, comparative genomics also facilitated the genetic explanation of the adaptation for host environment, which specify the protection mechanism against the invasion of foreign DNA (i.e. CRISPR/Cas locus), as well as carbohydrate fermentation. The 41 strains of P. acidilactici can metabolize a variety of carbon sources, which enhances the adaptability of this species and survival in different environments. This study evaluated the antibacterial ability, genome evolution, and ecological flexibility of P. acidilactici from the perspective of genetics and provides strong supporting evidence for its industrial development and application.

Escherichia coli EC93 deploys two plasmid-encoded class I contact-dependent growth inhibition systems for antagonistic bacterial interactions

The phenomenon of contact-dependent growth inhibition (CDI) and the genes required for CDI (cdiBAI) were identified and isolated in 2005 from an Escherichia coli isolate (EC93) from rats. Although the cdiBAIEC93 locus has been the focus of extensive research during the past 15 years, little is known about the EC93 isolate from which it originates. Here we sequenced the EC93 genome and find two complete and functional cdiBAI loci (including the previously identified cdi locus), both carried on a large 127 kb plasmid. These cdiBAI systems are differentially expressed in laboratory media, enabling EC93 to outcompete E. coli cells lacking cognate cdiI immunity genes. The two CDI systems deliver distinct effector peptides that each dissipate the membrane potential of target cells, although the two toxins display different toxic potencies. Despite the differential expression and toxic potencies of these CDI systems, both yielded similar competitive advantages against E. coli cells lacking immunity. This can be explained by the fact that the less expressed cdiBAI system (cdiBAIEC93-2) delivers a more potent toxin than the highly expressed cdiBAIEC93-1 system. Moreover, our results indicate that unlike most sequenced CDI+ bacterial isolates, the two cdi loci of E. coli EC93 are located on a plasmid and are expressed in laboratory media.

Bacteriocins in the Era of Antibiotic Resistance: Rising to the Challenge

Decades of antibiotic misuse in clinical settings, animal feed, and within the food industry have led to a concerning rise in antibiotic-resistant bacteria. Every year, antimicrobial-resistant infections cause 700,000 deaths, with 10 million casualties expected by 2050, if this trend continues. Hence, innovative solutions are imperative to curb antibiotic resistance. Bacteria produce a potent arsenal of drugs with remarkable diversity that are all distinct from those of current antibiotics. Bacteriocins are potent small antimicrobial peptides synthetized by certain bacteria that may be appointed as alternatives to traditional antibiotics. These molecules are strategically employed by commensals, mostly Firmicutes, to colonize and persist in the human gut. Bacteriocins form channels in the target cell membrane, leading to leakage of low-molecular-weight, causing the disruption of the proton motive force. The objective of this review was to list and discuss the potential of bacteriocins as antimicrobial therapeutics for infections produced mainly by resistant pathogens.

Natural bacterial isolates as an inexhaustible source of new bacteriocins

Microorganisms isolated from various traditionally fermented food products prepared in households without commercial starter cultures are designated as natural isolates. In addition, this term is also used for microorganisms collected from various natural habitats or products (silage, soil, manure, plant and animal material, etc.) that do not contain any commercial starters or bacterial formulations. They are characterized by unique traits that are the result of the selective pressure of environmental conditions, as well as interactions with other organisms. The synthesis of antimicrobial molecules, including bacteriocins, is an evolutionary advantage and an adaptive feature that sets them apart from other microorganisms from a common environment. This review aims to underline the knowledge of bacteriocins produced by natural isolates, with a particular emphasis on the most common location of their genes and operons, plasmids, and the importance of the relationship between the plasmidome and the adaptive potential of the isolate. Applications of bacteriocins, ranging from natural food preservatives to supplements and drugs in pharmacology and medicine, will also be addressed. The latest challenges faced by researchers in isolating new natural isolates with desired characteristics will be discussed, as well as the production of new antimicrobials, nearly one century since the first discovery of colicins in 1925. KEY POINTS: • Natural bacterial isolates harbor unique properties shaped by diverse interactions. • Horizontal gene transfer enables constant engineering of new antimicrobials. • Fermented food products are important source of bacteriocin-producing natural isolates.

Defending the homeland: microbiome molecules provide protection to their vertebrate hosts

Aim: The resident bacterial microbiome may shape and protect the health of vertebrate host. An array of molecules secreted by microbiome may contribute to the ecological stability of the microbiome itself. Material & methods: ELISA, radioactivity, immunofluorescence and cytokines measurements were used to observe the bioactivity and stability of colicin Ia level in oviparous and viviparous animal circulation. Results: Colicin Ia, a protein antimicrobial produced by Escherichia coli, is not present in animals at birth, but increases in concentration with the establishment of a stable gut microbiome and drops when the microbiome is experimentally disrupted. Colicin introduced in vivo is transported to tissues at concentrations able to prevent or eliminate bacterial infection. Conclusion: Our findings suggest an unexpected benefit provided by the presence of a resident microbiome in the form of active, circulating, bacterially-synthesized antimicrobial molecules.

High-Zinc Supplementation of Weaned Piglets Affects Frequencies of Virulence and Bacteriocin Associated Genes Among Intestinal Escherichia coli Populations

To prevent economic losses due to post-weaning diarrhea (PWD) in industrial pig production, zinc (Zn) feed additives have been widely used, especially since awareness has risen that the regular application of antibiotics promotes buildup of antimicrobial resistance in both commensal and pathogenic bacteria. In a previous study on 179 Escherichia coli collected from piglets sacrificed at the end of a Zn feeding trial, including isolates obtained from animals of a high-zinc fed group (HZG) and a corresponding control group (CG), we found that the isolate collection exhibited three different levels of tolerance toward zinc, i.e., the minimal inhibitory concentration (MIC) detected was 128, followed by 256 and 512 μg/ml ZnCl2. We further provided evidence that enhanced zinc tolerance in porcine intestinal E. coli populations is clearly linked to excessive zinc feeding. Here we provide insights about the genomic make-up and phylogenetic background of these 179 E. coli genomes. Bayesian analysis of the population structure (BAPS) revealed a lack of association between the actual zinc tolerance level and a particular phylogenetic E. coli cluster or even branch for both, isolates belonging to the HZG and CG. In addition, detection rates for genes and operons associated with virulence (VAG) and bacteriocins (BAG) were lower in isolates originating from the HZG (41 vs. 65% and 22 vs. 35%, p < 0.001 and p = 0.002, resp.). Strikingly, E. coli harboring genes defining distinct pathotypes associated with intestinal disease, i.e., enterotoxigenic, enteropathogenic, and Shiga toxin-producing E. coli (ETEC, EPEC, and STEC) constituted 1% of the isolates belonging to the HZG but 14% of those from the CG. Notably, these pathotypes were positively associated with enhanced zinc tolerance (512 μg/ml ZnCl2 MIC, p < 0.001). Taken together, zinc excess seems to influence carriage rates of VAGs and BAGs in porcine intestinal E. coli populations, and high-zinc feeding is negatively correlated with enteral pathotype occurrences, which might explain earlier observations concerning the relative increase of Enterobacterales considering the overall intestinal microbiota of piglets during zinc feeding trials while PWD rates have decreased.

Introduction to the Special Issue "Molecular Basis and the Pathogenesis of Enterohemorrhagic Escherichia coli Infections"

Although much of the world has progressed since the 1980s, our ability to treat infections with enterohemorrhagic Escherichia coli (EHEC) has unfortunately shown little improvement [...].

Escherichia coli: Physiological Clues Which Turn On the Synthesis of Antimicrobial Molecules

Zoonotic pathogens, like Shiga toxin-producing Escherichia coli (STEC) are a food safety and health risk. To battle the increasing emergence of virulent microbes, novel mitigation strategies are needed. One strategy being considered to combat pathogens is antimicrobial compounds produced by microbes, coined microcins. However, effectors for microcin production are poorly understood, particularly in the context of complex physiological responses along the gastro-intestinal tract (GIT). Previously, we identified an E. coli competitor capable of producing a strong diffusible antimicrobial with microcin-associated characteristics. Our objective was to examine how molecule production of this competitor is affected by physiological properties associated with the GIT, namely the effects of carbon source, bile salt concentration and growth phase. Using previously described liquid- and agar-based assays determined that carbon sources do not affect antimicrobial production of E. coli O103F. However, bile salt concentrations affected production significantly, suggesting that E. coli O103F uses cues along the GIT to modulate the expression of antimicrobial production. Furthermore, E. coli O103F produces the molecule during the exponential phase, contrary to most microcins identified to date. The results underscored the importance of experimental design to identify producers of antimicrobials. To detect antimicrobials, conventional microbiological methods can be a starting point, but not the gold standard.

Mining, heterologous expression, purification, antibactericidal mechanism, and application of bacteriocins: A review

Bacteriocins are generally considered as low-molecular-weight ribosomal peptides or proteins synthesized by G⁺ and G^- bacteria that inhibit or kill other related or unrelated microorganisms. However, low yield is an important factor restricting the application of bacteriocins. This paper reviews mining methods, heterologous expression in different systems, the purification technologies applied to bacteriocins, and identification methods, as well as the antibacterial mechanism and applications in three different food systems. Bioinformatics improves the efficiency of bacteriocins mining. Bacteriocins can be heterologously expressed in different expression systems (e.g., Escherichia coli, Lactobacillus, and yeast). Ammonium sulfate precipitation, dialysis membrane, pH-mediated cell adsorption/desorption, solvent extraction, macroporous resin column, and chromatography are always used as purification methods for bacteriocins. The bacteriocins are identified through electrophoresis and mass spectrum. Cell envelope (e.g., cell permeabilization and pore formation) and inhibition of gene expression are common antibacterial mechanisms of bacteriocins. Bacteriocins can be added to protect meat products (e.g., beef and sausages), dairy products (e.g., cheese, milk, and yogurt), and vegetables and fruits (e.g., salad, apple juice, and soybean sprouts). The future research directions are also prospected.

Potential of Bacteriocins from Lactobacillus taiwanensis for Producing Bacterial Ghosts as a Next Generation Vaccine

Bacteriocins are functionally diverse toxins produced by most microbes and are potent antimicrobial peptides (AMPs) for bacterial ghosts as next generation vaccines. Here, we first report that the AMPs secreted from Lactobacillus taiwanensis effectively form ghosts of pathogenic bacteria and are identified as diverse bacteriocins, including novel ones. In detail, a cell-free supernatant from L. taiwanensis exhibited antimicrobial activities against pathogenic bacteria and was observed to effectively cause cellular lysis through pore formation in the bacterial membrane using scanning electron microscopy (SEM). The treatment of the cell-free supernatant with proteinase K or EDTA proved that the antimicrobial activity is mediated by AMPs, and the purification of AMPs using Sep-Pak columns indicated that the cell-free supernatant includes various amphipathic peptides responsible for the antimicrobial activity. Furthermore, the whole-genome sequencing of L. taiwanensis revealed that the strain has diverse bacteriocins, confirmed experimentally to function as AMPs, and among them are three novel bacteriocins, designated as Tan 1, Tan 2, and Tan 3. We also confirmed, using SEM, that Tan 2 effectively produces bacterial ghosts. Therefore, our data suggest that the bacteriocins from L. taiwanensis are potentially useful as a critical component for the preparation of bacterial ghosts.

Bacteriotherapy in gastrointestinal cancer

The most prevalent gastrointestinal (GI) cancers include colorectal cancer, stomach cancer, and liver cancer, known as the most common causes of cancer-related death in both men and women populations in the world. Traditional therapeutic approaches, including surgery, radiotherapy, and chemotherapy have failed in the effective treatment of cancer. Therefore, there is an urgent need for finding new effective anticancer agents. The available evidence and also the promising results of using bacteria as the anticancer agents on numerous cancer cell lines have attracted the attention of scientists for the therapeutic role of bacteria in the field of cancer therapy. Moreover, several studies on the bacteriotherapy agents have used genetic engineering to overcome the challenges and enhance the efficacy with the least drawbacks. Numerous bacterial species that can specifically target and internalize into the tumor cells are used live, attenuated, or genetically as compared to selectively consider the hypoxic condition of tumor, which results in the tumor suppression. The present study is a comprehensive review of the current literature on the use of bacteria and their substances such as bacteriocins and toxins in the treatment of different types of gastrointestinal cancers.

Bacteriocins, Potent Antimicrobial Peptides and the Fight against Multi Drug Resistant Species: Resistance Is Futile?

Despite highly specialized international interventions and policies in place today, the rapid emergence and dissemination of resistant bacterial species continue to occur globally, threatening the longevity of antibiotics in the medical sector. In particular, problematic nosocomial infections caused by multidrug resistant Gram-negative pathogens present as a major burden to both patients and healthcare systems, with annual mortality rates incrementally rising. Bacteriocins, peptidic toxins produced by bacteria, offer promising potential as substitutes or conjugates to current therapeutic compounds. These non-toxic peptides exhibit significant potency against certain bacteria (including multidrug-resistant species), while producer strains remain insusceptible to the bactericidal peptides. The selectivity and safety profile of bacteriocins have been highlighted as superior advantages over traditional antibiotics; however, many aspects regarding their efficacy are still unknown. Although active at low concentrations, bacteriocins typically have low in vivo stability, being susceptible to degradation by proteolytic enzymes. Another major drawback lies in the feasibility of large-scale production, with these key features collectively limiting their current clinical application. Though such limitations require extensive research, the concept of expanding bacteriocins from food preservation to human health opens many fascinating doors, including novel drug delivery systems and anticancer treatment applications.