Optimization of Mycoremediation Potential of A Fungi: Aspergillus Ochraceus Strain

Mycoremediation is an important process that targets the removal of petroleum hydrocarbons by fungi. Accordingly, colorimetric method was used in the preliminary investigation of petroleum degradation with ten fungal strains as Aspergillus ochraceus, Aspergillus parasiticus, Aspergillus niger, Fusarium acuminatum, Fusarium graminearum, Fusarium equiseti, Fusarium oxysporum, Paecilomyces lilac, Penicillium crustosum, and Penicillium chrysogenum. Petroleum degradation of spore suspension, live biomass (fungal pellet and disc) and cell-free culture supernatant of the potent A. ochraceus strain were determined by gravimetric analysis. It was obtained that the fungal disc (94%) was more successful than the spore suspension (87%) in petroleum degradation under optimized conditions as pH:5.0, 1% of petroleum concentration, %5 (v/v) of inocum concentration, 1 g/100mL of inoculum amount and 7 days of incubation period. The degradation rate constant and half-life period of spore suspension were calculated as 0.291 day− 1 and t1/2 = 0.340 and of fungal disc were 0.401 day− 1 and t1/2 = 0.247. 7.5% and 10% (v/v) concentration of cell-free culture supernatant were achieved more than 80% of petroleum removal. However, the cell-free culture supernatant was not as effective as fungal disc. According to GC/MS analysis, the fungal disc of A. ochraceus strain degraded long chain n-alkanes such as C35 and C36 more effectively than n-alkanes in the range of C22-C34. Drop-collapse and oil-spreading methods showed that A. ochraceus is a good biosurfactant producer. This study clearly pointed out that Aspergillus ochraceus NRRL 3174 strain with high its removal capacity can be used as an effective agent in petroleum bioremediation process.

Antagonistic Potential of Dairy Origin Enterococcus faecium Against Multidrug-Resistant Foodborne Pathogens

Probiotic potential of Enterococcus spp. is widely investigated around the globe. The biochemically and molecular characterized E. faecium strains isolated from Dahi (continental yogurt) were evaluated to tolerate simulated gastric environment, bile, sodium chloride, temperature, and pH. The safety was assessed by disc diffusion, broth microdilution, antibiotic resistance genes screening, and hemolytic ability. Enterococci survived simulated gastrointestinal conditions and depicted growth at temperature (15 to ≥42°C), pH (≤2.5 to ≥9.5), 0.3% bile salt and 3% NaCl. All strains were sensitive to ampicillin, vancomycin, kanamycin, gentamicin, streptomycin, tetracycline and ciprofloxacin and harbored vanR, vanX, qnrB2, qnrS, tetK, and tetW resistance genes. E. faecium strains inhibited the E. coli (85%) and S. Typhi (50%) whereas the 10% cell-free culture supernatant (CFCS) of E. faecium halted the growth of E. coli while 15% CFCS completely suppressed S. Typhi. The cell-free culture supernatant retained antibacterial nature after pH and proteinase K treatment, however, it lost activity after heat treatment (≥95°C). The genetic screening revealed that all isolates are capable to produce putrescine biogenic amine. Further assessment of strains for lack of infectivity, cytotoxicity in animals, adhesion to Caco-2 cells and characterization of enterocins is essential to conclude the probiotic potential of these strains.

Production of biologically active human interleukin-10 by Bifidobacterium bifidum BGN4

Background Bifidobacterium spp. are representative probiotics that play an important role in the health of their hosts. Among various Bifidobacterium spp., B. bifidum BGN4 exhibits relatively high cell adhesion to colonic cells and has been reported to have various in vivo and in vitro bio functionalities (e.g., anti-allergic effect, anti-cancer effect, and modulatory effects on immune cells). Interleukin-10 (IL-10) has emerged as a major suppressor of immune response in macrophages and other antigen presenting cells and plays an essential role in the regulation and resolution of inflammation. In this study, recombinant B. bifidum BGN4 [pBESIL10] was developed to deliver human IL-10 effectively to the intestines. Results The vector pBESIL10 was constructed by cloning the human IL-10 gene under a gap promoter and signal peptide from Bifidobacterium spp. into the E. coli-Bifidobacterium shuttle vector pBES2. The secreted human IL-10 from B. bifidum BGN4 [pBESIL10] was analyzed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), Western Blotting, and enzyme-linked immunosorbent assay (ELISA). More than 1,473 ± 300 ng/mL (n = 4) of human IL-10 was obtained in the cell free culture supernatant of B. bifidum BGN4 [pBESIL10]. This productivity is significantly higher than other previously reported human IL-10 level from food grade bacteria. In vitro functional evaluation of the cell free culture supernatant of B. bifidum BGN4 [pBESIL10] revealed significantly inhibited interleukin-6 (IL-6) production in lipopolysaccharide (LPS)-induced Raw 264.7 cells (n = 6, p < 0.0001) and interleukin-8 (IL-8) production in LPS-induced HT-29 cells (n = 6, p < 0.01) or TNFα-induced HT-29 cells (n = 6, p < 0.001). Conclusion B. bifidum BGN4 [pBESIL10] efficiently produces and secretes significant amounts of biologically active human IL-10. The human IL-10 production level in this study is the highest of all human IL-10 production reported to date. Further research should be pursued to evaluate B. bifidum BGN4 [pBESIL10] producing IL-10 as a treatment for various inflammation-related diseases, including inflammatory bowel disease, rheumatoid arthritis, allergic asthma, and cancer immunotherapy.

Exploring Antifouling Activity of Biosurfactants Producing Marine Bacteria Isolated from Gulf of California

Biofouling causes major problems and economic losses to marine and shipping industries. In the search for new antifouling agents, marine bacteria with biosurfactants production capability can be an excellent option, due to the amphipathic surface-active characteristic that confers antimicrobial and antibiofilm activities. The aim of this study was to evaluate the antifouling activity of biosurfactants producing marine bacteria from the Gulf of California. The cell free culture supernatant (CFCS) of Bacillus niabensis (S-69), Ralstonia sp. (S-74) (isolated from marine sediment) and of B. niabensis (My-30) (bacteria associated to the sponge Mycale ramulosa) were screened for production of biosurfactants (using hemolysis and drop collapse test, oil displacement and emulsifying activity). The toxicity and antifouling activity were evaluated against biofoulers (bacteria forming biofilm and macrofoulers) both in laboratory and field assays. The results indicate that all bacteria were biosurfactant producers, but the higher capability was shown by B. niabensis (My-30) with high emulsifying properties (E24) of 71%. The CFCS showed moderate toxicity but were considered non-toxic against Artemia franciscana at low concentrations. In the antifouling assay, the CFCS of both strains of B. niabensis showed the best results for the reduction of the biofilm formation (up 50%) against all Gram-positive bacteria and most Gram-negative bacteria with low concentrations. In the field assay, the CFCS of B. niabensis (My-30) led to the reduction of 30% of biofouling compared to the control. The results indicate that the biosurfactant produced by B. niabensis (My-30) has promising antifouling activity.

Organic acids and 2,4-Di-tert-butylphenol: major compounds of Weissella confusa WM36 cell-free supernatant against growth, survival and virulence of Salmonella Typhi

Background Salmonella Typhi (S. Typhi), the causative agent of typhoid fever, causes serious systemic disease in humans. Antibiotic treatment is required for the S. Typhi infection, while the inappropriate use of antibiotics causes increased drug-resistant S. Typhi. Hence, alternative therapies through non-antibiotic approaches are urgently needed. The use of beneficial lactic acid bacterium and/or its metabolites to control typhoid fever represent a promising approach, as it may exert protective actions through various mechanisms. Method In this study, the cell-free culture supernatant (CFCS) of Weissella confusa WM36 was evaluated via the antibacterial activity, and its metabolites were identified. In addition, the effects of CFCS on Salmonella virulence behaviors were also investigated. Result Based on strong inhibition the growth of S. Typhi DMST 22842, organic acids (lactic acid and acetic acid) and 2,4-Di-tert-butylphenol (2,4 DTBP), were the main antibacterial metabolites presented in CFCS of strain WM36. Minimum inhibitory concentration (MIC) at 40% WM36–CFCS dramatically reduced the S. Typhi population to more than 99.99% at 4 h and completely inhibited biofilm formation, while sub-MIC at 20% (v/v) and MIC could reduce 100% of motility. Additionally, sub-MIC at only 10% (v/v) WM36–CFCS did down-regulate the expression of virulence genes which are responsible for the type-III secretion system, effector proteins, and quorum sensing system in this pathogen. Conclusion W. confusa WM36 and its metabolites are shown to be a promising candidates, and an effective approach against typhoid Salmonella burden.

New Insights into cytotoxic metabolites produced by Streptomyces griseus isolate KJ623766: Large scale production, structure elucidation and biological activities

Natural products particularly microbial metabolites have been the mainstay of cancer chemotherapy and are likely to provide many of the lead structures and derivatives with new biological activities. In this research, the production of some potential cytotoxic metabolites from Streptomyces (S.) griseus isolate KJ623766 was carried out in 1 4 L laboratory fermenter under specified optimum conditions (28°C temperature, 200 RPM rotation speed, uncontrolled PH, 3 vvm aeration and 2 bar airflow pressure). Using 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyl tetrazolium-bromide (MTT) assay, the cytotoxic activity of the ethyl acetate (1:1, v/v) extract of cell free culture supernatant (CFCS) against Caco2 and Hela cancer cell lines was determined with CD 50 of 14 µg/ml and 20 µg/ml, respectively. Bioassay guided fractionation of the ethyl acetate extract using different chromatographic techniques had led to the purification of the cytotoxic metabolites coded W1, R1 and R2 with reproducible amounts of 20, 5, and 1.5 mg/l, respectively. The structures of respective metabolites were determined using various spectroscopic analysis and identified as genistein, β-rhodomycinone and γ- rhodomycinone, respectively. Accordingly, S. griseus isolate KJ623766 can be used as a potential industrial strain for the large scale production of the isoflavonoid genistein, as well as for the production of β-and γ- rhodomycinone to be used for the construction of new derivatives with more potent cytotoxic activities of the anthracycline family. This is the first report about the production of the isoflavonoid genistein by S. griseus KJ623766.