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A total of 246 bacterial isolates were collected from various food and animal sources within Nanning city, China. Sequencing of the 16S rRNA gene revealed that 24.4% of the isolates were lactic acid bacteria (LAB). Initial screens identified three isolates from semi-hard cheese: Lactobacillus plantarum subsp. plantarum strains K3 and K4 and Lb. paracasei subsp. tolerans K8; and one from raw buffalo milk: Lb. plantarum subsp. plantarum E41 as having the highest levels of cell surface hydrophobicity and auto-aggregation. Further characterization of these strains showed that all four isolates were completely stable after exposure to the pepsin and trypsin for 6 hours, and strains K8 and E41 remained viable after 6 hours of exposure to acidic conditions (pH 2.5) and bile salts (0.3%). In addition, strains K3 and K4 were shown to inhibit the growth of potential human pathogens, including methicillin resistant Staphylococcus aureus, Escherichia coli and Salmonella typhi, with inhibition zones being >14 mm for each bacterial target. Results from this study suggested that the four characterized LAB strains could survive passage through the gastrointestinal tract, thus supporting the need for additional studies to assess their potential as probiotics.

The world faces a challenge with the pervasion of multidrug-resistant bacteria that encourages scientists to develop and discover alternative, ecofriendly, and easy-to-produce new antibacterial agents. Our work is part of the greater effort of scientists around the world to achieve this goal by the biological synthesis of silver nanoparticles using cyanobacterial extracellular and intracellular components as nonchemical reducing agents. Two Egyptian cyanobacteria were isolated and identified according to 16S rRNA gene sequencing as

Background The health-promoting effects along with global economic importance of consuming food products supplemented with probiotic microorganisms encouraged the researchers to discover new probiotics. Results Fourteen lactic acid bacterial isolates were identified as Enterococcus mediterraneensis, Lactobacillus fermentum, and Streptococcus lutetiensis by 16S rRNA gene sequencing, and in vitro characterized for their actual probiotic potential. All E. mediterraneensis isolates were resistant to clindamycin, whereas Lb. fermentum isolates were resistant to ampicillin, clindamycin, and vancomycin. The E. mediterraneensis and Lb. fermentum isolates displayed high overall digestive survival, ranged from 1.35 ± 0.06 to 32.73 ± 0.84% and from 2.01 ± 0.01 to 23.9 ± 1.85%, respectively. All isolates displayed cell surface hydrophobicity, ranged between 15.44 ± 6.72 and 39.79 ± 2.87%. The strongest auto-aggregation capability, higher than 40%, was observed for most E. mediterraneensis and Lb. fermentum isolates. The E. mediterraneensis isolates (L2, L12, and L15), Lb. fermentum (L8, L9, and L10), and Strep. lutetiensis (L14) exhibited the greatest co-aggregation with Salmonella typhimurium, Escherichia coli O157:H7, Staphylococcus aureus, and Bacillus cereus. Fifty-seven and fourteen hundredth percent of E. mediterraneensis isolates could be considered bacteriocinogenic against E. coli O157:H7, B. cereus, and S. aureus. Conclusion This study is the first one to isolate Enterococcus mediterraneensis in Egypt and to characterize it as new species of probiotics globally. According to the results, E. mediterraneensis (L2, L12, and L15), Lb. fermentum (L8, L9, and L10), and Strep. lutetiensis (L14) are the most promising in vitro probiotic candidates.

Plant microbiota have co-evolved with their associated plants in the entire holobiont, and their assemblages support diversity, health and productivity on our planet. Of importance is the in vitro cultivation and identification of their hub taxa for possible core microbiome modification. Therefore, we recently introduced the in situ-similis culturing strategy, based on the use of plant leaves as platform for in vitro growth of plant microbiota. Here, we augment the strategy by the incorporation of the Most Probable Number (MPN) method, based on the use of leaf strips and root segments immersed in plain semi-solid water agar, as growth milieu. Cultivability of bacterial endophytes of sunflower plants (Helianthus annuus L.) was monitored in terms of MPN population estimates, community composition through PCR-DGGE analysis and 16S rRNA gene sequencing of representative isolates. The method efficiently enriched the plant endophytes as MPN estimates exceeded log 7.0 g-1 leaf/root. Results of PCR-DGGE analyses indicated divergence in community composition of cultivable bacterial endophytes primarily attributed to the type of culture media, signaling a certain degree of plant-organ specificity and compatibility. Based on 16S rRNA gene sequencing of representative bacterial isolates, 20 genera comprising 32 species were enriched in leaf strips- and root segments-based media. They belonged to the three phyla Bacteroidetes, Firmicutes and Proteobacteria, especially Alpha- and Gammaproteobacteria. The MPN strategy furnished a diversified nutritive platform in terms of homologous/heterologous and ambient/limited oxygenic cultivation. As a result, cultivability was extended to more 8 genera - Bosea, Brevundimonas, Caulobacter, Chitinophaga, Pseudoxanthomonas, Scandinavium, Sphingobacterium, Starkeya - among them three genera, namely Caulobacter, Scandinavium and Starkeya, which were not yet reported for Sunflower, even with the use of metagenomics sequencing methods. Possible unknown species or even one new putative genus were enriched. Thus, not only potential members of the major microbiome but also the rare isolates of satellite microbiomes can be isolated using the presented in situ similis MPN-cultivation strategy. It is a feasible addition to traditional cultivation methods to probe deeper for both the major and rare taxa and fill the many cultivation gaps within plant microbiota.

The world faces a challenge with pervasion of multidrug resistant bacteria which encouraged the scientists to develop and discover alternative ecofriendly and easy to produce new antibacterial agents. Two Egyptian cyanobacteria were isolated and identified according to 16S rRNA gene sequencing as Phormidium ambiguum and Desertifilum tharense . The sequences were deposited in the GenBank with accession numbers of MW762709 and MW762710 for Desertifilum tharense and Phormidium ambiguum, respectively. These isolates have the ability to produce silver nanoparticles (Ag-NPs) extra- and intracellularly under light and dark conditions. The results of UV-Vis analysis showed promising extracellular Ag-NPs synthesis by Desertifilum tharense and Phormidium ambiguum under light conditions. Therefore, these Ag-NPs were characterized and evaluated for antibacterial and antioxidant activity. TEM, SEM and XRD analyses revealed the spherical crystals with face-centered cubic structures and size range of 6.24–11.4 nm and 6.46–12.2 nm for Ag-NPs of Desertifilum tharense and Phormidium ambiguum , respectively. XRD and EDX results clearly confirmed the successful synthesis of Ag-NPs in its oxide form or chloride form. The FTIR spectrum data confirmed the presence of hydroxyl and amide groups. Desertifilum tharense Ag-NPs displayed the largest inhibition zone ranged from 9 mm against Micrococcus luteus ATCC 10240 to 25 mm against methicillin resistant S. aureus (MRSA) ATCC 43300. For Phormidium ambiguum Ag-NPs, the inhibition zone diameter was in a range of 9–18 mm. The Ag-NPs of Phormidium ambiguum exhibited the highest scavenging activity of 48.7% comparing with that of Desertifilum tharense which displayed 43.753%.

The recent introduction of plant-only-based culture media enabled cultivation of not-yet-cultured bacteria that exceed 90% of the plant microbiota communities. Here, we further prove the competence and challenge of such culture media, and further introduce “the inoculum-dependent culturing strategy, IDC”. The strategy depends on direct inoculating plant serial dilutions onto plain water agar plates, allowing bacteria to grow only on the expense of natural nutrients contained in the administered inoculum. Developed colonies are successively transferred/subcultured onto plant-only-based culture media, which contains natural nutrients very much alike to those found in the prepared plant inocula. Because of its simplicity, the method is recommended as a powerful tool in screening programs that require microbial isolation from a large number of diverse plants. Here, the method comfortably and successfully recovered several isolates of endophytic Actinobacteria represented by the six genera of Curtobacterium spp., Plantibacter spp., Agreia spp., Herbiconiux spp., Rhodococcus spp., and Nocardioides spp. Furthermore, two of the isolates are most likely novel species belonging to Agreia spp. and Herbiconiux spp.

Water blooms are a serious environmental problem affecting fresh and marine ecosystem. Application of probiotic bacteria has been introduced as an emerging and eco-friendly tool to regulate or inhibit cyanobacterial blooms. In the present study, we have isolated and morphologically identified cyanobacteria from El Manzala Lake. Afterward, we examined the use of probiotic lactic acid bacteria MT2 (Lactobacillus sakei) isolated from Nile Tilapia (Oreochromis niloticus) intestine in controlling Anabaena sp. and Oscillatoria sp., isolated from El Manzala Lake. Measuring chlorophyll, phycocyanin and biomass concentration were conducted in a co-culture experiment between the selected cyanobacterial isolates and probiotic lactic acid bacteria (MT2). Chlorophyll content, phycocyanin content and biomass concentration of Anabaena sp., and Oscillatoria sp., were decreased significantly in the co-culture experiment with MT2 bacteria. Also, the microscopic examinations showed that MT2 bacterium was able to lysis and degrade the selected cyanobacterial cells under microscope. We concluded that the use of MT2 (Lactobacillus sakei) is potentially effective against some cyanobacteria especially Anabaena sp. and Oscillatoria sp.

Chickpea legumin has a high molecular weight (300 KDa), consists of 5 subunits (25–45 KDa) and has a relatively high isoelectric point (pH 6.5). It could inhibit the growth of four bacteria strains (Staph. aureus, P. aeruginosa, E. coli and B. subtilis), grown in agar (MIC = 100–150 g/ml) and bring the liquid bacterial growth to their minimum levels after 24 h of incubation using 1 MIC. Transmission electron microscopy micrographs of Staph. aureus (Gram positive) and P. aeruginosa (Gram negative) treated by 150 μg/ml chickpea legumin (1 MIC) showed cellular swelling and cell membrane disintegration explaining the mode of action of this protein. Minced beef samples supplemented with 200 μg/g chickpea legumin extended the storage time to 14–15 days instead of 7–8 days in case of un-supplemented control and 10–11 days in case of nisin, reducing the total viable count by 2.6–2.9 log compared to control against a reduction of 1.6 log in case of nisin.

Camel whey (CW) was hydrolysed with papain from Carica papaya and fractionated by size exclusion chromatography (SEC). The antibacterial activity of the CW, camel whey hydrolysate (CWH) and the obtained SEC-fractions was assessed using the disc-diffusion method. The CWH exhibited significantly higher antibacterial activity than the unhydrolysed CW. SEC-F2 (fraction 2) exhibited the highest antibacterial activity against Staphylococcus aureus , whereas Escherichia coli was the least affected. Transmission electron microscopy (TEM) micrographs showed that the SEC-F2 caused changes in the treated bacterial cells. Additionally, LC/MS analysis was used to characterise the peptides profile of CW, CWH and SEC-F2. Two major peptides (414.05 and 456.06 Da mass) were detected in CWH and SEC-F2, with higher concentration in the latter. This study has demonstrated that hydrolysis of CW with papain generates a wide range of potent antibacterial peptides against selected pathogenic bacteria.

Goat whey hydrolysates were produced from goat whey using Alcalase ® from Bacillus licheniformis . The goat whey hydrolysate (GWH) with the highest degree of hydrolysis was fractionated by size exclusion chromatography (SEC), and the antibacterial activity of the GWH and the obtained SEC-fractions were evaluated using the disc diffusion method. The results showed that the GWH exhibited significantly higher antibacterial activity than the unhydrolysed goat whey. Among all SEC fractions obtained, only SEC-F 2 and SEC-F 3 showed antibacterial activity against the tested bacteria. SEC-F 3 exhibited the highest antibacterial effectiveness against Escherichia coli and Bacillus cereus with MIC values of 0.09 and 0.03 mg/mL respectively, whereas, SEC-F 3 and SEC-F 2 had comparable MIC values against Staphylococcus aureus (∼0.02 mg/mL). Transmission electron microscopy showed that the GWH caused changes in the bacterial cells affected. Additionally, LC–MS analysis was used to characterize the peptides of GWH and SEC-F 3 . Two major peptides were detected in GWH and SEC-F 3 , with higher concentration in the latter, having masses of 730 and 1183 Da, respectively. These results suggest that hydrolysis of goat whey by Alcalase is an easy tool to enhance its antibacterial activities. GWH and its effective antibacterial fractions may be used to control the undesirable bacteria in food and improve its safety.

Although plant-based culture media enhances in vitro cultivation of rhizobacteria, studies assessing their biomass potential for large-scale applications are lacking. Here, we advance plant pellets (PPs) as a novel technology to unlock the potential of such vegan culture media for biomass production of Rhizobium leguminosarum. PP formulations were based on mixtures of Egyptian clover powder and the agro-byproducts glycerol and molasses. These mixtures were either contained or not contained in teabags during culture media preparation. Metrics of biomass included colony forming units, optical density (OD600nm), and cell dry weight (DW). Biomass comparisons between culture media based on PPs and standard yeast extract mannitol (YEM) revealed that the following PPs composition, contained in teabags, cultivated rhizobia at levels comparable to YEM: 16 g clover powder, 5% molasses, and 0.8% glycerol. This PPs composition enabled shorter generation times of rhizobia (PP: 3.83 h, YEM: 4.28 h). Strikingly, PPs mixtures supplemented with 10% molasses and not contained in teabags promoted rhizobia without apparent lag phases and produced 25% greater DW than YEM. PPs potentiate the use of dehydrated vegan feedstocks for both plant microbiota cultivation and biomass production and appear as cost- and labor-effective tools, easy to handle and store for plant-based culture media preparation.