Natural tetracycline (TC) antibiotics were the first major class of therapeutics to earn the distinction of 'broad-spectrum antibiotics' and they have been used since the 1940s against a wide range ...of both Gram-positive and Gram-negative pathogens, mycoplasmas, intracellular chlamydiae, rickettsiae and protozoan parasites. The second generation of semisynthetic tetracyclines, such as minocycline and doxycycline, with improved antimicrobial potency, were introduced during the 1960s. Despite emerging resistance to TCs erupting during the 1980s, it was not until 2006, more than four decades later, that a third--generation TC, named tigecycline, was launched. In addition, two TC analogues, omadacycline and eravacycline, developed
(semi)synthetic and fully synthetic routes, respectively, are at present under clinical evaluation. Interestingly, despite very productive early work on the isolation of a
mutant strain that produced 6-demethyl-7-chlortetracycline, the key intermediate in the production of second- and third-generation TCs, biosynthetic approaches in TC development have not been productive for more than 50 years. Relatively slow and tedious molecular biology approaches for the genetic manipulation of TC-producing actinobacteria, as well as an insufficient understanding of the enzymatic mechanisms involved in TC biosynthesis have significantly contributed to the low success of such biosynthetic engineering efforts. However, new opportunities in TC drug development have arisen thanks to a significant progress in the development of affordable and versatile biosynthetic engineering and synthetic biology approaches, and, importantly, to a much deeper understanding of TC biosynthesis, mostly gained over the last two decades.
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Pharmaceutical industry has been encountering antimicrobial activity of non-antibiotics during suitability tests carried out prior to routine pharmacopoeial microbiological purity ...analysis of finished dosage forms. These properties are usually ignored or perceived as a nuisance during pharmaceutical analysis.
The aim of this study was: (i) to compare the available data to our method suitability test results carried out on products containing ibuprofen, i.e. to demonstrate that method suitability can be a valuable tool in identifying new antimicrobials, (ii) to demonstrate the antimicrobial activity of ibuprofen and ibuprofen lysine.
Microbiological purity method suitability testing was carried out according to European Pharmacopoeia (EP), chapters 2.6.12. and 2.6.13. Antimicrobial activity of ibuprofen and ibuprofen lysine was demonstrated by a disk diffusion method, a modification of the European Committee for Antimicrobial Susceptibility Testing method (EUCAST), against test microorganisms recommended in the EP.
It was confirmed that ibuprofen may be responsible for the broad spectrum of antimicrobial activity of the tested products, and that method suitability tests according to the EP can indeed be exploited by the scientific community in setting guidelines towards future research of new antimicrobials. In the disk diffusion assay, inhibition zones were obtained with more than 62.5μg and 250μg for Staphylococcus aureus, 125μg and 250μg for Bacillus subtilis, 31.3μg and 125μg for Candidaalbicans, 31.3μg and 62.5μg for Aspergillusbrasiliensis, of ibuprofen/disk, and ibuprofen lysine/disk, respectively. For Escherichiacoli, Pseudomonasaeruginosa and Salmonellatyphimurium inhibition zones were not obtained.
Antimicrobial activity of ibuprofen is considered merely as a side effect, and it is not mentioned in the patient information leaflets of ibuprofen drugs. As such, for the patient, it could represent an advantage, but, it could also introduce additional risks during usage. Further microbiological, pharmacological and clinical trials are of great importance.
Lactiplantibacillus plantarum D13 shows antistaphylococcal and antilisterial activity, probably due to the synthesis of a presumptive bacteriocin with antibiofilm capacity released in the cell-free ...supernatant (CFS), whose inhibitory effect is enhanced by cocultivation with susceptible strains. An in silico analysis of the genome of strain D13 confirmed the pln gene cluster. Genes associated with plantaricin biosynthesis, structure, transport, antimicrobial activity, and immunity of strain D13 were identified. Furthermore, the predicted homology-based 3D structures of the cyclic conformation of PlnE, PlnF, PlnJ, and PlnK revealed that PlnE and PlnK contain two helices, while PlnF and PlnJ contain one and two helices, respectively. The potential of the strain to modulate the intestinal microbiota in healthy or dextran sulphate sodium (DSS)-induced colitis mouse models was also investigated. Strain D13 decreased the disease activity index (DAI) and altered the gut microbiota of mice with DSS-induced colitis by increasing the ratio of beneficial microbial species (Allobaculum, Barnesiella) and decreasing those associated with inflammatory bowel disease (Candidatus Saccharimonas). This suggests that strain D13 helps to restore the gut microbiota after DSS-induced colitis, indicating its potential for further investigation as a probiotic strain for the prevention and treatment of colitis.
The antimicrobial activity of industrially important lactic acid bacteria as starter cultures and probiotic bacteria is the main subject of this review. This activity has been attributed to the ...production of metabolites such as organic acids (lactic and acetic acid), hydrogen peroxide, ethanol, diacetyl, acetaldehyde, acetoine, carbon dioxide, reuterin, reutericyclin and bacteriocins. The potential of using bacteriocins of lactic acid bacteria, primarily used as biopreservatives, represents a perspective, alternative antimicrobial strategy for continuously increasing problem with antibiotic resistance. Another strategy in resolving this problem is an application of probiotics for different gastrointestinal and urogenital infection therapies. Key words: antimicrobial activity, bacteriocins, lactic acid bacteria, probiotics, starter cultures
We evaluated the functional capacity of plantaricin-producing Lactobacillus plantarum SF9C and S-layer-carrying Lactobacillus brevis SF9B to withstand gastrointestinal transit and to compete among ...the gut microbiota in vivo. Considering the probiotic potential of Lb. brevis SF9B, this study aims to investigate the antibacterial activity of Lb. plantarum SF9C and their potential for in vivo colonisation in rats, which could be the basis for the investigation of their synergistic functionality.
A plantaricin-encoding cluster was identified in Lb. plantarum SF9C, a strain which efficiently inhibited the growth of Listeria monocytogenes ATCC
19111™ and Staphylococcus aureus 3048. Homology-based three-dimensional (3D) structures of SF9C plantaricins PlnJK and PlnEF were predicted using SWISS-MODEL workspace and the helical wheel representations of the plantaricin peptide helices were generated by HELIQUEST. Contrary to the plantaricin-producing SF9C strain, the S-layer-carrying SF9B strain excluded Escherichia coli 3014 and Salmonella enterica serovar Typhimurium FP1 from the adhesion to Caco-2 cells. Finally, PCR-DGGE analysis of the V2-V3 regions of the 16S rRNA gene confirmed the transit of the two selected lactobacilli through the gastrointestinal tract (GIT). Microbiome profiling via the Illumina MiSeq platform revealed the prevalence of Lactobacillus spp. in the gut microbiota of the Lactobacillus-treated rats, even on the 10th day after the Lactobacillus application, compared to the microbiota of the healthy and AlCl
-exposed rats before Lactobacillus treatment.
The combined application of Lb. plantarum SF9C and Lb. brevis SF9B was able to influence the intestinal microbiota composition in rats, which was reflected in the increased abundance of Lactobacillus genus, but also in the altered abundances of other bacterial genera, either in the model of healthy or aberrant gut microbiota of rats. The antibacterial activity and capacity to withstand in GIT conditions contributed to the functional aspects of SF9C and SF9B strains that could be incorporated in the probiotic-containing functional foods with a possibility to positively modulate the gut microbiota composition.
Fermented sausages have been manufactured traditionally in the Mediterranean basin. Istrian sausages are one of the many regionally specific products distinguished by the specific traditional recipes ...and consequentially exceptional sensory characteristics. The aim of this study was to evaluate sensory, physico-chemical and microbiological changes occurring during production and ripening of Istrian sausages made at traditional households, and to compare the results obtained with the identical product produced in industrial conditions. Additional goal was to characterise the autochthonous lactic acid bacteria populations and to obtain the candidate starter strains. Production stages and product ripening parameters could be strictly defined in controlled industrial conditions of the production process, and the results of this study can serve to standardise the production of traditional Istrian sausages. The results from sensory and physico-chemical examination do not show differences in relation to sausages of a similar type investigated in other papers. Lactic acid bacteria were favoured during fermentation at rising salt concentrations, consisting mostly of
Lactobacillus
strains followed with the abundance of coagulase-negative cocci. Further, we targeted the autochthonous lactic LAB population to select the candidate starter strains for controlled sausage fermentation. Fifty Gram-positive strains with catalase-negative phenotype, rod-shape or cocci morphology, effective acidification kinetics and production of lactic acid identified by sequence analysis of 16S rRNA were considered LAB. The selected LAB strains were able to grow in a range of pH values and high salt concentration important for their metabolic activity during sausage fermentation. According to our results,
Lactobacillus sakei
, which is a prevalent strain during fermentation of various types of fermented sausages, was frequently detected.
Lactobacillus plantarum
and
Lactobacillus curvatus
were also detected in abundance, implying their possible competitiveness among the complex microbial population. Isolated autochthonous strains
L. curvatus
S30,
L. sakei
S32 and
L. plantarum
S50 produced high lactic acid concentrations, tolerated NaCl concentrations present during sausage fermentation, survived at high concentrations of hydrogen ions and inhibited six pathogens associated with contamination of meat products in a strain-specific manner.
: Probiotic strain Lactobacillus plantarum L4 and strain Leuconostoc mesenteroides LMG 7954 were applied for the controlled fermentation of cabbage heads. The parameters of the controlled and ...spontaneous fermentations, including antimicrobial effect of cabbage brines obtained at the end of both fermentations, were monitored. To check out the influence of starter culture strains, 10 randomly chosen lactic acid bacteria, isolated at the end of controlled cabbage heads fermentation were identified by API 50CHL test, and the presence of the probiotic culture was confirmed by Pulsed Field Gel Electrophoresis. The starter cultures applied for cabbage heads fermentation allowed lowering of NaCl concentrations from 4.0% to 2.5% (w/v), considerably accelerated fermentation process by 14 d, and improved the product quality. The produced sauerkraut heads are considered probiotic product as viable probiotic cells count in final product was higher than 106 colony‐forming units (CFU) per gram of product.
Practical Application: The results of this research could be applied in the production of fermented cabbage heads with added functional (probiotic) value and with lower NaCl concentration with expected shortened fermentation time. This could not only be of economic but also of ecological importance.
Spontaneous sauerkraut fermentation was performed at industrial scale in “Prehrana Inc.”, Varaždin, in order to select autochthonous lactic acid bacteria (LAB) which were evaluated according ...probiotic criteria and tested for their capacity as probiotic starter cultures. At the end of the spontaneous sauerkraut fermentation, total LAB counts reached 9.0×105CFU/ml. This underlines that the need for addition of the well characterised probiotic cultures, in appropriate viable cell counts, would be valuable in probiotic sauerkraut production. Phenotypic characterisation through API 50 CHL and SDS-PAGE of cell protein patterns revealed that Lactobacillus plantarum is predominant LAB strain in homofermentative phase of fermentation. Autochthonous LAB isolates SF1, SF2, SF4, SF9 and SF15 were selected based on the survival in in vitro gastrointestinal tract conditions. RAPD fingerprints indicated that the selected autochthonous LAB were distinct from one another. All of the strains efficiently inhibited the growth of indicator strains and satisfied technological properties such as acidification rate, tolerance to NaCl and viability during freeze-drying. Strains Lb. paraplantarum SF9 and Lb. brevis SF15, identified by AFLP DNA fingerprints, have shown the best properties to be applied as probiotic starter cultures, because of their highest adhesion to Caco-2 cells and expression of specific, protective S-layer proteins of 45kDa in size. With addition of these strains, probiotic attribute of the sauerkraut will be achieved, including health promoting, nutritional, technological and economic advantages in large scale industrial sauerkraut production.
The goal of this study was the characterisation of indigenous lactic acid bacteria (LAB) and yeasts isolated from nine white pickled (BG) and nine fresh soft (ZG) artisanal cheeses collected in ...Serbia and Croatia. While LAB were present in all of the cheeses collected, yeasts were found in all BG cheeses but only in three ZG cheese samples. High LAB and yeast species diversity was determined (average H′L=0.4 and H′Y=0.8, respectively). The predominant LAB species in white pickled (BG) cheeses were Lactococcus lactis, Lactobacillus plantarum, and Leuconostoc mesenteroides, while in fresh soft (ZG) cheeses the most dominant LAB species were L. lactis, Enterococcus faecalis, and Leuconostoc pseudomesenteroides. Among the 20 yeast species found, Debaryomyces hansenii, Candida zeylanoides, and Torulaspora delbrueckii were found to be predominant in BG cheeses, while Yarrowia lipolytica was predominant in ZG cheeses. The characterisation of metabolic and technological potentials revealed that 53.4% of LAB isolates produced antimicrobial compounds, 44.3% of LAB strains showed proteolytic activity, while most of the yeast species possessed either lipolytic or proteolytic activity. In conclusion, the results obtained in this study showed that the composition of LAB and yeast populations in white pickled and fresh soft cheeses is region specific. The knowledge gained in this study could eventually be used to select region specific LAB and yeast strains for the production of white pickled and fresh soft artisanal cheeses with geographically specific origins under controlled conditions.
•Indigenous microbiota of 18 artisanal cheeses from Serbia and Croatia was determined.•LAB and yeast species were identified by using traditional and molecular methods.•High diversity of LAB and yeast populations were found.•Impact on starter culture development for traditional cheeses with defined properties•Implementation in controlled production of artisanal cheeses with geographical origin
The objective of this study was the characterisation of the S-layer protein (SlpA) and its functional role in the probiotic activity of
Lactobacillus helveticus
M92. SlpA was isolated and identified ...by SDS-PAGE LC-MS/MS analysis. The
slpA
gene encoding the SlpA from
L. helveticus
M92 was sequenced and compared with other well characterised
slpA
genes. Sequence similarity searches revealed high homology with the SlpA of
Lactobacillus
strains. Purified SlpA showed significantly better immunomodulatory effects in orally immunised mice than
L. helveticus
M92 cells after SlpA removal. SlpA is involved in the autoaggregation of
L. helveticus
M92 cells and coaggregation of
L. helveticus
M92 with
S.
Typhimurium FP1 as these processes were negatively affected after SlpA removal from the cell surface. Therefore, the influence of oral treatment with
L. helveticus
M92 on an oral infection of mice by
S.
Typhimurium FP1 was investigated. Following the oral immunization of mice, with viable
L. helveticus
M92 and
S.
Typhimurium FP1 cells, the concentration in the luminal contents of total S-IgA and specific anti-
Salmonella
S-IgA antibodies, from all immunized mice was significantly higher compared to the control group or a group of mice infected only with
S.
Typhimurium FP1. These results demonstrate that the observed reduced infection by
S.
Typhimurium FP1 in mice with
L. helveticus
M92 is associated with competitive exclusion in the intestinal tract and enhanced immune protection conferred by the
L. helveticus
M92 and its SlpA.
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