Diversity and Succession of Microbiota during Fermentation of the Traditional Indian Food Idli.

Idli, a naturally fermented Indian food, is prepared from a mixture of rice and black gram (lentil). To understand its microbial community during fermentation, detailed analysis of the structural and functional dynamics of the idli microbiome was performed by culture-dependent and -independent approaches. The bacterial diversity and microbial succession were assessed at different times of fermentation by 16S rRNA amplicon sequencing. Results highlighted that most microbiota belonged to phylum Firmicutes (70%) and Proteobacteria (22%). Denaturing gradient gel electrophoresis (DGGE) and quantitative PCR (qPCR) analysis confirmed the diversity and succession involved therein. A culture-dependent approach revealed that the microbially diverse populations were conserved across different geographical locations. The fermentation was primarily driven by lactic acid bacteria as they constitute 86% of the total bacterial population, and genus Weissella emerged as the most important organism in fermentation. The natural microbiota of the grains mainly drives the fermentation, as surface sterilized grains did not show any fermentation. Growth kinetics of idli microbiota and physicochemical parameters corroborated the changes in microbial dynamics, acid production, and leavening occurring during fermentation. Using a metagenomic prediction tool, we found that the major metabolic activities of these microbial fermenters were augmented during the important phase of fermentation. The involvement of the heterofermentative hexose monophosphate (HMP) pathway in batter leavening was substantiated by radiolabeled carbon dioxide generated from d-[1-14C]-glucose. Hydrolases degrading starch and phytins and the production of B vitamins were reported. Moreover, culturable isolates showing beneficial attributes, such as acid and bile tolerance, hydrophobicity, antibiotic sensitivity, and antimicrobial activity, suggest idli to be a potential dietary supplement.IMPORTANCE This is a comprehensive analysis of idli fermentation employing modern molecular tools which provided valuable information about the bacterial diversity enabling its fermentation. The study has demonstrated the relationship between the bacterial population and its functional role in the process. The nature of idli fermentation was found to be more complex than other food fermentations due to the succession of the bacterial population. Further studies using metatranscriptomics and metabolomics may enhance the understanding of this complex fermentation process. Moreover, the presence of microorganisms with beneficial properties plausibly makes idli a suitable functional food.

In vitro antibacterial activity of Tabernaemontana alternifolia (Roxb) stem bark aqueous extracts against clinical isolates of methicillin resistant Staphylococcus aureus.

BACKGROUND: The rise of antibiotic resistance among methicillin resistant Staphylococcus aureus (MRSA), have caused concerns for the treatment of MRSA infections. Hence, search for an alternative therapy for these infections is inevitable. Folk Indian medicine refers to the use of leaf and stem bark powder of Tabernaemontana alternifolia (Roxb) in treatment of skin infections, but no scientific report establishes its antibacterial activity. METHODS: Direct aqueous extracts and sequential aqueous extracts of the stem bark of T. alternifolia (using petroleum ether and ethyl acetate as other solvents) were prepared by soxhlet extraction. The antibiotic sensitivity profiles of the clinical isolates were determined against 18 antibiotics using disc diffusion method. The isolates were identified by 16S rRNA gene sequencing. The methicillin resistance among S. aureus (MRSA) was confirmed by PCR amplification of mecA gene. The disc diffusion method was used to determine the antibacterial activity of the extracts. The micro-dilution method was used to determine the minimum inhibitory concentration (MIC) of the extract against the test organism. To further evaluate the therapeutic potential of the extract, cell cytotoxicity was checked on Vero cells by MTT assay. Chemical profiling of the extract was done by HPTLC method. RESULTS: The aqueous extracts of T. alternifolia stem bark exhibited antibacterial activity against Gram-positive microorganisms, particularly against clinical isolates of MRSA and vancomycin resistant S. aureus (VRSA). The minimum inhibitory concentration (MIC) of extract against the isolates ranged from 600-800 µg/ml. The extract did not exhibit cytotoxic activity against Vero cells even at the concentration of 4 mg/ml. The chemical profiling revealed presence of alkaloids, flavonoids, coumarins, saponins and steroids. Petroleum ether and ethyl acetate extracts did not exhibit antibacterial activity. CONCLUSION: Our results offer a scientific basis for the traditional use of T. alternifolia in the treatment of skin infections, showing that the plant extract has an enormous potential as a prospective alternative therapy against MRSA skin infections. The present study lays the basis for future studies, to validate the possible use of T. alternifolia as a candidate in the treatment of MRSA infections.

Cytoprotection and immunomodulation in cancer therapy.

Bioprospecting and natural products drug development for cancer treatment has become an important area. Most of the cancer chemotherapeutic agents are associated with toxicity towards normal cells and tissues. Optimal dosing of cancer chemotherapeutic agents is often limited because of severe non-myelosuppressive and myelosuppressive toxicities. It is a continuing challenge to design therapy that is safer, effective and selective. Cytoprotective agents offer opportunities to reduce treatment related toxicity of anticancer therapy without diminution of efficacy. None of the available agents satisfy criteria for an ideal cytoprotection. This has stimulated research for discovering natural resources with immunomodulatory and cytoprotective activities. This article describes chemical agents presently employed in clinical practice and reviews ethnopharmacological agents reported to have chemoprotective, radioprotective, immunomodulating, adaptogenic and antitumour activities.

Immunoprotection by botanical drugs in cancer chemotherapy.

Most of the synthetic chemotherapeutic agents available today are immunosuppressants, cytotoxic, and exert variety of side effects that are particularly evident in cancer chemotherapy. Botanical based immunomodulators are often employed as supportive or adjuvant therapy to overcome the undesired effects of cytotoxic chemotherapeutic agents and to restore normal health. Total extract, polar and non-polar extracts, and their formulations, prepared from medicinal plants mentioned in Ayurveda, namely, Withania somnifera (Linn Dunal) (Solanaceae), Tinospora cordifolia (Miers) (Menispermaceae), and Asparagus racemosus (Willd.) (Liliaceae), exhibited various immunopharmacological activities in cyclophosphamide (CP)-treated mouse ascitic sarcoma. Treatment of ascitic sarcoma-bearing mice with a formulation of total extracts of Withania somnifera and Tinospora cordifolia (80:20) and alkaloid-free polar fraction of Withania somnifera resulted in protection towards CP-induced myelo- and immunoprotection as evident by significant increase in white cell counts and hemagglutinating and hemolytic antibody titers. Treatment with these candidate drugs will be important in development of supportive treatment with cancer chemotherapy.

Immunoadjuvant potential of Asparagus racemosus aqueous extract in experimental system.

The immunoadjuvant potential of Asparagus racemosus (Willd.) Family (Liliaceae) aqueous root extract was evaluated in experimental animals immunized with diphtheria, tetanus, pertussis (DTP) vaccine. Immunostimulation was evaluated using serological and hematological parameters. Oral administration of test material at 100 mg/kg per day dose for 15 days resulted significant increase (P = 0.0052) in antibody titers to Bordtella pertussis as compared to untreated (control) animals. Immunized animals (treated and untreated) were challenged with B. pertussis 18323 strain and the animals were observed for 14 days. Results indicate that the treated animals did show significant increase in antibody titers as compared to untreated animals after challenge (P = 0.002). Immunoprotection against intra-cerebral challenge of live B. pertussis cells was evaluated based on degree of sickness, paralysis and subsequent death. Reduced mortality accompanied with overall improved health status was observed in treated animals after intra-cerebral challenge of B. pertussis indicating development of protective immune response. Present study indicates applications of test material as potential immunoadjuvant that also offers direct therapeutic benefits resulting in less morbidity and mortality.