Anticandidal effect of endophytic bacteria isolated from Equisetum arvense L. against Candida albicans and Candida glabrata

ABSTRACT Equisetum arvense, a fern species possesses a number of pharmaceutical prospective. In the present study, a total of 103 endophytic bacteria isolated from E. arvense and were evaluated for their anticandidal property against five Candida species, two C. albicans, C. glabrata, C. saitoana and C. geochares. Out of them fifty one were identified as per the morphological and molecular characterisation using 16S rRNA gene sequencing and among them, ten promising endophytic bacteria were mentioned in the present study. Among ten endophytic bacteria, Psychrobacillus insolitus and Curtobacterium oceanosedimentum exerted highest anticandidal effect against C. albicans KACC 30062 and C. glabrata KBNO6P00368, with diameter of inhibition zones of 21.30±0.41 and 18.24±0.12 mm, respectively. When the endophytic bacteria cultures were successively fractionated using different solvents, only the butanol fraction of Psychrobacillus insolitus and Curtobacterium oceanosedimentum had anticandidal activity, with inhibition zones of 20.12±0.28 mm and 12.33±0.11 mm, respectively. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values of the butanol fractions ranged from 250 to 500 and 500 to 1,000 µg/mL, respectively. Scanning electron microscope (SEM) analysis showed impaired membrane of C. albicans and C. glabrata at the MIC, indicating that butanol extract lysed the cell membrane and caused cell death. The endophytic bacteria derived from E. arvense can be a valuable resource for the development of natural anticandidal agents to manage candidiasis.

Production of gaba (γ - aminobutyric acid) by microorganisms: a review

GABA (γ-aminobutyric acid) is a four carbon non-protein amino acid that is widely distributed in plants, animals and microorganisms. As a metabolic product of plants and microorganisms produced by the decarboxylation of glutamic acid, GABA functions as an inhibitory neurotransmitter in the brain that directly affects the personality and the stress management. A wide range of traditional foods produced by microbial fermentation contain GABA, in which GABA is safe and eco-friendly, and also has the possibility of providing new health-benefited products enriched with GABA. Synthesis of GABA is catalyzed by glutamate decarboxylase, therefore, the optimal fermentation condition is mainly based on the biochemical properties of the enzyme. Major GABA producing microorganisms are lactic acid bacteria (LAB), which make food spoilage pathogens unable to grow and act as probiotics in the gastrointestinal tract. The major factors affecting the production of GABA by microbial fermentation are temperature, pH, fermentation time and different media additives, therefore, these factors are summarized to provide the most up-dated information for effective GABA synthesis. There has been a huge accumulation of knowledge on GABA application for human health accompanying with a demand on natural GABA supply. Only the GABA production by microorganisms can fulfill the demand with GABA-enriched health beneficial foods.

Quantitative real-time PCR method to detect changes in specific transcript and total RNA amounts

Quantitative real-time PCR (qRT-PCR), used in conjunction with reverse transcriptase, has been applied to the determination of the number of copies of a transcript per unit mass of RNA, but did not indicate any change in the amount of total RNA per mass of tissue. In the present work, we described a simple method to use qRT-PCR to estimate the change in the amount of total RNA per unit mass of wheat (Triticum aestivum L.) tissue in response to cold temperature. Three qRT-PCR templates, i.e. control, cold-exposed, and one of RNA extracted from a sample consisting of equal masses of control and cold-exposed tissue, were analyzed. The number of copies of target transcript per unit mass of RNA was estimated from the three samples using standard qRT-PCR techniques. Equations describing the number of copies of the target sequence in each of the tissue samples were solved simultaneously to describe the relative proportion of the target sequence that originated from each tissue sample in the mixture, thereby providing an estimate of relative amounts of total RNA in the two tissues.