Effects of mastic resin and its essential oil on the growth of proteolytic Clostridium botulinum

Phenolic compounds as natural microbial toxin detoxifying agents

Despite the abundance of promising studies, developments, and improvements about the elimination of microbial toxins from food matrices, they are still considered as one of the major food safety problems due to the lack of their complete avoidance even today. Every year, many crops and foodstuffs have to be discarded due to unconstrained contamination and/or production of microbial toxins. Furthermore, the difficulty for the detection of toxin presence and determination of its level in foods may lead to acute or chronic health problems in many individuals. On the other hand, phenolic compounds might be considered as microbial toxin detoxification agents because of their inhibition effect on the toxin synthesis of microorganisms or exhibiting protective effects against varying damaging mechanisms caused by toxins. In this study, the effect of phenolic compounds on the synthesis of bacterial toxins and mycotoxins is comprehensively reviewed. The potential curing effect of phenolic compounds against toxin-induced damages has also been discussed. Consequently, phenolic compounds are indicated as promising, and considerable natural preservatives against toxin damages and their detoxification potentials are pronounced.

Genomic Diversity, Competition, and Toxin Production by Group I and II Clostridium botulinum Strains Used in Food Challenge Studies

Botulinum neurotoxins (BoNTs) produced by the bacteria Clostridium botulinum are the causative agent of human and animal botulism, a rare but serious and potentially deadly intoxication. Foodborne botulism is caused by the consumption of foods containing BoNTs, which results from contamination of foods with C. botulinum spores and toxin production by the bacteria during growth within the food. Validation of the safety of food products is essential in preventing foodborne botulism, however, limited guidance and standards exist for the selection of strains used in C. botulinum food challenge studies. Sequencing and genomics studies have revealed that C. botulinum is a large, diverse, and polyphyletic species, with physiologic and growth characteristics studied only in a few representatives. Little is known about potential growth competition or effects on toxin production between C. botulinum strains. In this study, we investigated an applied cocktail of ten C. botulinum strains, seven Group I and three Group II. Whole genome SNP alignments revealed that this strain cocktail encompasses the major clades of the Group I and II C. botulinum species. While growth competition appears to exist between several of the strains, the cocktail as a whole resulted in high levels of BoNT production.

Three classes of plasmid (47-63 kb) carry the type B neurotoxin gene cluster of group II Clostridium botulinum

Pulsed-field gel electrophoresis and DNA sequence analysis of 26 strains of Group II (nonproteolytic) Clostridium botulinum type B4 showed that 23 strains carried their neurotoxin gene cluster on a 47–63 kb plasmid (three strains lacked any hybridization signal for the neurotoxin gene, presumably having lost their plasmid). Unexpectedly, no neurotoxin genes were found on the chromosome. This apparent constraint on neurotoxin gene transfer to the chromosome stands in marked contrast to Group I C. botulinum, in which neurotoxin gene clusters are routinely found in both locations. The three main classes of type B4 plasmid identified in this study shared different regions of homology, but were unrelated to any Group I or Group III plasmid. An important evolutionary aspect firmly links plasmid class to geographical origin, with one class apparently dominant in marine environments, whereas a second class is dominant in European terrestrial environments. A third class of plasmid is a hybrid between the other two other classes, providing evidence for contact between these seemingly geographically separated populations. Mobility via conjugation has been previously demonstrated for the type B4 plasmid of strain Eklund 17B, and similar genes associated with conjugation are present in all type B4 plasmids now described. A plasmid toxin–antitoxin system pemI gene located close to the neurotoxin gene cluster and conserved in each type B4 plasmid class may be important in understanding the mechanism which regulates this unique and unexpected bias toward plasmid-borne neurotoxin genes in Group II C. botulinum type B4.

Review of the inhibition of biological activities of food-related selected toxins by natural compounds

There is a need to develop food-compatible conditions to alter the structures of fungal, bacterial, and plant toxins, thus transforming toxins to nontoxic molecules. The term 'chemical genetics' has been used to describe this approach. This overview attempts to survey and consolidate the widely scattered literature on the inhibition by natural compounds and plant extracts of the biological (toxicological) activity of the following food-related toxins: aflatoxin B1, fumonisins, and ochratoxin A produced by fungi; cholera toxin produced by Vibrio cholerae bacteria; Shiga toxins produced by E. coli bacteria; staphylococcal enterotoxins produced by Staphylococcus aureus bacteria; ricin produced by seeds of the castor plant Ricinus communis; and the glycoalkaloid α-chaconine synthesized in potato tubers and leaves. The reduction of biological activity has been achieved by one or more of the following approaches: inhibition of the release of the toxin into the environment, especially food; an alteration of the structural integrity of the toxin molecules; changes in the optimum microenvironment, especially pH, for toxin activity; and protection against adverse effects of the toxins in cells, animals, and humans (chemoprevention). The results show that food-compatible and safe compounds with anti-toxin properties can be used to reduce the toxic potential of these toxins. Practical applications and research needs are suggested that may further facilitate reducing the toxic burden of the diet. Researchers are challenged to (a) apply the available methods without adversely affecting the nutritional quality, safety, and sensory attributes of animal feed and human food and (b) educate food producers and processors and the public about available approaches to mitigating the undesirable effects of natural toxins that may present in the diet.

Enlightening the past: analytical proof for the use of Pistacia exudates in ancient Egyptian embalming resins

Mastic, the resinous exudate of the evergreen shrub Pistacia lentiscus, is frequently discussed as one of the ingredients used for embalming in ancient Egypt. We show the identification of mastic in ancient Egyptian embalming resins by an unambiguous assignment of the mastic triterpenoid fingerprint consisting of moronic acid, oleanonic acid, isomasticadienonic and masticadienonic acid through the consolidation of NMR and GC/MS analysis. Differences in the observed triterpenoid fingerprints between mummy specimens suggest that more than one plant species served as the triterpenoid resin source. Analysis of the triterpenoid acids of ancient embalming resin samples in the form of their methyl- and trimethylsilyl esters is compared. In addition we show a simple way to differentiate between residues of mastic from its use as incense during embalming or from direct mastic application in the embalming resin.

Independent evolution of neurotoxin and flagellar genetic loci in proteolytic Clostridium botulinum

Background

Proteolytic Clostridium botulinum is the causative agent of botulism, a severe neuroparalytic illness. Given the severity of botulism, surprisingly little is known of the population structure, biology, phylogeny or evolution of C. botulinum. The recent determination of the genome sequence of C. botulinum has allowed comparative genomic indexing using a DNA microarray.

Results

Whole genome microarray analysis revealed that 63% of the coding sequences (CDSs) present in reference strain ATCC 3502 were common to all 61 widely-representative strains of proteolytic C. botulinum and the closely related C. sporogenes tested. This indicates a relatively stable genome. There was, however, evidence for recombination and genetic exchange, in particular within the neurotoxin gene and cluster (including transfer of neurotoxin genes to C. sporogenes), and the flagellar glycosylation island (FGI). These two loci appear to have evolved independently from each other, and from the remainder of the genetic complement. A number of strains were atypical; for example, while 10 out of 14 strains that formed type A1 toxin gave almost identical profiles in whole genome, neurotoxin cluster and FGI analyses, the other four strains showed divergent properties. Furthermore, a new neurotoxin sub-type (A5) has been discovered in strains from heroin-associated wound botulism cases. For the first time, differences in glycosylation profiles of the flagella could be linked to differences in the gene content of the FGI.

Conclusion

Proteolytic C. botulinum has a stable genome backbone containing specific regions of genetic heterogeneity. These include the neurotoxin gene cluster and the FGI, each having evolved independently of each other and the remainder of the genetic complement. Analysis of these genetic components provides a high degree of discrimination of strains of proteolytic C. botulinum, and is suitable for clinical and forensic investigations of botulism outbreaks.

Mastic Oil from Pistacia lentiscus var. chia Inhibits Growth and Survival of Human K562 Leukemia Cells and Attenuates Angiogenesis

Mastic oil from Pistacia lentiscus var. chia, a natural plant extract traditionally used as a food additive, has been extensively studied for its antimicrobial activity attributed to the combination of its bioactive components. One of them, perillyl alcohol (POH), displays tumor chemopreventive, chemotherapeutic, and antiangiogenic properties. We investigated whether mastic oil would also suppress tumor cell growth and angiogenesis. We observed that mastic oil concentration and time dependently exerted an antiproliferative and proapoptotic effect on K562 human leukemia cells and inhibited the release of vascular endothelial growth factor (VEGF) from K562 and B16 mouse melanoma cells. Moreover, mastic oil caused a concentration-dependent inhibition of endothelial cell (EC) proliferation without affecting cell survival and a significant decrease of microvessel formation both in vitro and in vivo. Investigation of underlying mechanism(s) demonstrated that mastic oil reduced 1) in K562 cells the activation of extracellular signal-regulated kinases 1/2 (Erk1/2) known to control leukemia cell proliferation, survival, and VEGF secretion and 2) in EC the activation of RhoA, an essential regulator of neovessel organization. Overall, our results underscore that mastic oil, through its multiple effects on malignant cells and ECs, may be a useful natural dietary supplement for cancer prevention.