Pre-formulation and delivery strategies for the development of bacteriocins as next generation antibiotics

peer-reviewedBacteriocins, a class of antimicrobial peptide produced by bacteria, may offer a potential alternative to traditional antibiotics, an important step towards mitigating the ever increasing antimicrobial resistance crisis. They are active against a range of clinically relevant Gram-positive and Gram-negative bacteria. Bacteriocins have been discussed in the literature for over a century. Although they are used as preservatives in food, no medicine based on their antimicrobial activity exists on the market today. In order to formulate them into clinical antibiotics, pre-formulation studies on their biophysical and physicochemical properties that will influence their activity in vivo and their stability during manufacture must be elucidated. Thermal, pH and enzymatic stability of bacteriocins are commonly studied and regularly reported in the literature. Solubility, permeability and aggregation properties on the other hand are less frequently reported for many bacteriocins, which may contribute to their poor clinical progression. Promising cytotoxicity studies report that bacteriocins exhibit few cytotoxic effects on a variety of mammalian cell lines, at active concentrations. This review highlights the lack of quantitative data and in many cases even qualitative data, on bacteriocins’ solubility, stability, aggregation, permeability and cytotoxicity. The formulation strategies that have been explored to date, proposed routes of administration, trends in in vitro/in vivo behaviour and efforts in clinical development are discussed. The future promise of bacteriocins as a new generation of antibiotics may require tailored local delivery strategies to fulfil their potential as a force to combat antimicrobial-resistant bacterial infections

Suillus mediterraneensis from the Algerian Coastline: Morphological Recognition and Mycochemical Profiling

Suillus mediterraneensis is an ectomycorrhizal mushroom of two-needle pines. The purpose of the present study is to initially determine the morphological characterization of the species and, thereafter, the mycochemical investigation of the hydro-methanolic extract in order to identify the main chemical classes of their composition in terms of secondary metabolites using simple and rapidly recognized methods and techniques. This survey is being carried out in the coastal region of Ghazaouet within the wilaya of Tlemcen. The morphological determination of the mushroom is based on a range of macroscopic features, including the cap (by its shape, size, color, and surface or its cuticle), the hymenophore, the hymenium (tubes: their color, their shape, and the way they are attached), the stipe (thickness and shape), and the flesh. Furthermore, microscopic examination, either fresh or with reagents, especially Melzer’s reagent, is needed to determine the shape, ornamentation, and size of the spores. The macro-chemical reaction of the different parts can be useful. This identification allows us to determine the species S. mediterraneensis, the family of Suillaceae, under Pinus halepensis with the presence of granules on the stipe. The results of the mycochemical screening carried out on the extract showed the presence of substances belonging to the classes of active compounds that include flavonoids, tannins, alkaloids, free quinones, reducing compounds, and coumarins. Anthraquinones, terpenoids, and saponins are absent. These preliminary results encourage the characterization of other molecules, and further studies are needed to evaluate their biological activities

Lactose consumption in whey by new Lactobacillus plantarum strains isolated from Camel milk

Lactic acid bacteria have a wide range of applications in fermented food industry that can ferment carbohydrates to produce lactic acid. These bacteria have the particularity of having in their enzymatic baggage a particular enzyme, which is β-galactosidase, capable of degrading lactose and splitting it into galactose and glucose. The aim of present research was to select and investigate through some Lactobacillus plantarum isolated from camel milks from the Algerian Sahara, those most active in the degradation of lactose contained in whey from local manufacturing plant soft cheeses called camembert (Sidi Saada Relizane, Algeria). Results showed that among the eight isolated strains, four strains showed an interesting rates of consumption of lactose contained in whey, and which are in decreasing order P3, P8, P6 and P5, corresponding respectively to the percentages of 29.12, 28.82, 25.72 and 21.19%. Kinetic behaviors of five Lactobacillus strains were investigated with Contois model, data showed that the highest biomass production was obtained with the strain Lactobacillus P3 with 0.09 g g−1, followed by P2 and P6 with 0.08 g g−1, then followed by P8 and P5 with 0.07 g g−1. Whereas the rest of the strains, they appears to have a lower biomass production compared to others in decreasing order: P1 (0.06 g g−1), P4 and P7 (0.05 g g−1). These results reflect the capacity of these strains as well as their strong lactose degradation activity, this property would be important in particular for the use and possible exploitation of its strains in food industry, in particular dairy products, in order to in the recovery of whey which constitute a major waste from the dairy industry, which minimizes the risk of pollution. These strains can also be used in food products containing a low level of lactose, which will be intended for consumer suffering from lactose intolerance.</jats:p

Antagonistic activity of Lactobacillus rhamnosus LbRE-LSAS and some Bifidobacterium sp against Shigella sonnei

Since their discovery, antibiotics have been one of the most useful tools in the struggle against infectious disease. However, due to their overuse, numerous pathogens developed multiple resistances against antibiotics. Searching and studying antagonistic GRAS (generally recognized as save) bacteria is a promising field to find innovating treatment against infectious diseases. Lactic acid bacteria and Bifidobacterium are GRAS bacteria well known for their antagonistic effect on other microorganisms including pathogens such as Shigella sonnei. The antagonistic activity of Lactobacillus rham-nosus LbRE-LSAS strain and four strains of Bifidobacterium genera: longum (Bl431 and Bl432), bifidum (Bb442) and animalis. sbsp lactis (Bb12), was evaluated using two different techniques: Spot On Agar Test (SPAT) and Agar well diffusion test (AWDT) against Shigella sonnei (Ss CECT 457), Micrococcus luteus (M1-CECT241) and five lactic indicator strains: Carnobacterium maltoaromaticum CECT 5805), Lactobacillus plantarum (LbP CECT 748), Pedio-coccus pentosaceus (Pp CECT 4695), Lactobacillus acidophilus (LbA CECT 4529), Lactobacillus sakei (Lbs 673). We noted a maximum diameter of the inhibition zone by SPAT technique with strain the Bb12 (16.67 mm) followed by the strain LbRE-LSAS (16.42 mm). However, the maximum diameter of the inhibition zone using SPAT technique was obtained with the strain Bb12 (11.89 mm) followed by the strain LbRE-LSAS (11.11 mm). The antagonistic activity against Shigella sonnei was also evaluated using the coculture method. The maximum inhibition observed after 24 h of coculture was 6.54 log recorded with the strain LbRE-LSAS. Through these results we can clearly deduce the antagonistic potential of the two strains Lactobacillus rhamnosus LbRE-LSAS and Bifidobacterium longum Bl431, as to prevent or treat any shigellosis caused by Shigella sonnei.</jats:p