Browsing by Author "Gayathri, M"

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    Isolation and characterization of beneficial rhizosphere microorganisms from ragi grown in Attappady hill tract of Kerala
    (Department of Agricultural Microbiology, College of Agriculture, Vellayani, 2021) Gayathri, M; Chitra, N
    The study entitled “Isolation and characterization of beneficial rhizosphere microorganisms from ragi grown in Attappady hill tract of Kerala” was conducted during the year 2019-2021 in the Department of Agricultural Microbiology, College of Agriculture, Vellayani, Thiruvananthapuram with the objective to isolate nitrogen fixing and phosphate solubilizing bacteria from soil and root samples collected from Attapady and select efficient isolates through in vitro screening process and assess the plant growth promotion activity by roll towel assay. Thirty six nitrogen fixing bacteria and eight phosphate solubilizing bacteria were isolated from root and soil samples from ragi grown in Attappady region. The isolates were designated as ATY1-ATY36 for NFB isolates and PSB1-PSB8 for PSB isolates. Twenty isolates were selected after eliminating isolates with similarities in colony morphological characters, in order to avoid repetition among the isolates obtained from the same sample. Both NFB and PSB isolates were characterized by morphology and biochemical tests. All selected isolates were subjected to plant growth promotion activity studies. The Indole Acetic Acid (IAA) production showed a wide range of variation from 101.22 µg mL-1 to 3.26 µg mL-1 . Gibberellic Acid (GA) production of all the twenty isolates were done and the results ranged between 10.07 µg mL-1 and 2.18 µg mL-1 . Maximum IAA and GA production was recorded in isolate ATY10. Extracellular ammonia production of the bacterial isolates ranged between 176.53±5.07 μmol mL−1 and 75.59 μmol mL−1. The nitrogen content of NFB isolates ranged between 30.75 µg mL-1 and 9 µg mL-1 . The isolate ATY33 had maximum nitrogen content. The selected PSB isolates were subjected to plate assay and broth assay using Pikovskaya’s medium. The isolate PSB1 recorded maximum zone of solubilization (18.23 mm), phosphate solubilizing index (2.82) and quantification of phosphate solubilization (53.41 mg L-1 ). The bacterial isolates were screened based on weighted average ranking. In NFB, ATY10, ATY34 and ATY35 were selected for further studies and in PSB, the isolates PSB1, PSB3 and PSB4 were selected. The selected isolates were 164 identified as Pantoea agglomerans ATY10, Rhizobium sp. ATY34, Ensifer adhaerens ATY35, Burkholderia territorii PSB1, Burkholderia cepacia PSB3 and Aeromonas hydrophila PSB4 by 16s rRNA sequencing. Effect of these isolates were assessed for plant growth promotion in vitro in ragi seeds using roll towel assay. Maximum germination percentage was recorded by Aeromonas hydrophila PSB4 (81.24 per cent) and the minimum number of days taken for germinationwas recorded by Pantoea agglomerans ATY10 treated seeds. Also, the treatment Pantoea agglomerans ATY10 recorded maximum shoot length (3.31 cm), root length (7.76 cm), seedling length (11.08 cm), seedling vigour index (876.62), root dry weight (0.443 mg) and root shoot ratio (0.50). The treatment Burkholderia territorii PSB1 recorded maximum root fresh weight (3.762 mg) and shoot dry weight (0.877 mg). The six isolates were subjected to assess the multiple traits such as phosphorus, potassium and silicate solubilizing capacity, siderophore production and antifungal activity. Burkholderia territorii PSB1 showed maximum zone of inhibition against Rhizoctonia solani (3.16 mm) and Sclerotium rolfsii (0.58 mm). The maximum antagonistic activity against Fusarium sp. and Helminthosporium sp. was recorded by Burkholderia cepacia PSB3 with 4.13 mm and 5.66 mm of zone of inhibition respectively. Burkholderia territorii PSB1 and Burkholderia cepacia PSB3 solubilized potassium alumino silicate in agar also, with clearance zone of 11.00 mm and 12.66 mm (in diameter), respectively. None of the isolates solubilized magnesium trisilicate in Bunt and Rovira medium. The siderophore production was observed in Aeromonas hydrophila PSB4 isolate in Chrome Azurol S (CAS) agar medium plates. Based on the results of the present study, it can be concluded that Pantoea agglomerans ATY10 is the superior isolate among NFB isolates for plant growth promotion. Also, the isolate Burkholderia territorii PSB1 is best among PSB isolates for plant growth promotion and biocontrol activity.
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    Value addition and quality evaluation of holy basil (Ocimum tenuiflorum L.)
    (Department of Community Science, College of Agriculture, Vellanikkara, 2023) Gayathri, M; Seeja Thomachan Panjikkaran
    Holy basil is the most renowned medicinal herb and is known as the mother of necessities for its infinite therapeutic benefits. It is referred to as the "Queen of Herbs," and the Sanskrit word "tulsi" means "incomparable." It is one of the oldest herbs in the Lamiaceae family and is widely cultivated throughout the subcontinent. The physicochemical composition of the holy basil accession (KAU-OC25) (IC-0640854) used in this research had a moisture content of 89.4%, and the levels of the macronutrients, protein and fat per 100 g were found to be 2.99 g and 0.61 g, respectively. It was revealed that the herb had a crude fibre content of 10.48 g/100 g. In terms of vitamin content, ascorbic acid was found to be 30.4 mg/g, and the amount of beta carotene was 2826.92 µg/100 g. In 100g of the sample, the holy basil contained 26.9 mg of calcium, 28 mg of iron, 4.2 mg of zinc, and 224 mg of phosphorus, respectively. The total flavonoid and phenol levels were 41.41 mg QE (quercetin equivalent) and 66.66 mg GAE (gallic acid equivalent) respectively. Holy basil has phytate, oxalate, and tannin concentrations of 3.99 mg/100 g, 2.33 mg/100 g, and 9.74 mg/100 g, respectively. The phytochemical makeup of the herb was analysed through chromatographical tools like O-HRLCMS and GCMS/Ms. The analysis revealed thirty eight medicinally active bioactive compounds namely eugenol, methyl eugenol, kaempferol, scutellarin, rosmarinic acid, luteolin, ursolic acid, vicenin, apigenin 7-O-glucuronide, genistein 4-O- glucuronide, betaine, ϒ- aminobutyric acid (GABA), fisetin, orientin, choline, DL-stachydrine, oleanolic acid, luteolin-7-Oglucuronide, baicalin, β-caryophyllene, ostruthin, hexadecanoic acid, 5 amino pentanoic acid, taxifolin, alpha-pinene, alpha-terpineol, chavicol, alpha cubabene, eucalyptol, estragole, alpha-caryophyllene, alpha-bisabolol, beta-ocimene, terpinene-4-ol and trans-4-thujanol and carvacrol. Eugenol has a number of protective qualities against a variety of conditions that can be fatal, including cancer, oxidative stress, inflammation, hyperglycemia, and elevated cholesterol. Kaempferol and scutellarin are powerful antioxidant flavonoids while rosmarinic acid is known to be effective against microorganisms like the herpes simplex virus. Luteolin and ursolic acid were reported to have potent anti-cancer properties. The active flavonoid derivative apigenin-7-O-D-glucuronide has a variety of pharmacological properties, such as antioxidant, anti-complement, and aldose reductase inhibitory properties. Fisetin, ursolic acid and oleanolic acid have proven anti-cancer activities. ϒaminobutyric acid (GABA) has a number of physiological effects, including lowering blood pressure, boosting immunity, improving cognitive function, inhibiting the proliferation of cancer cells, and reducing sleeplessness. The flavonol taxifolin exhibits strong antioxidant, reducing, radical-scavenging, and metal chelating properties. Anti-oxidative and anti-inflammatory activities are demonstrated by luteolin-7-O-glucuronide. Baicalin significantly reduces the replication of HIV 1. Carvacrol is a potent antioxidant and a great adaptogen to treat hepatic stress. Alpha-pinene, alpha-terpineol, estragole, alpha-caryophyllene and alpha-bisabolol had potent anti-inflammatory activity whereas beta-ocimene, chavicol, terpinene-4-ol and trans-4-thujanol has proven antimicrobial activities. Docking studies of the compounds revealed that six compounds namely kaempferol, baicalin, luteolin, rosmarinic acid and eugenol can be considered for further studies regarding the treatment of type 2 diabetes mellitus and fourteen compounds namely scutellarin, vicenin, ursolic acid, genistein 4-O-glucuronide, betaine, taxifolin, apigenin 7-O-glucuronide, ϒ-aminobutyric acid (GABA), 5 amino pentanoic acid, kaempferol, baicalin, luteolin, rosmarinic acid and eugenol display noteworthy anti-covid action. The successfully docked compounds were tested for drug-likeness using ADMET analysis which revealed that rosmarinic acid, kaempferol, luteolin, and taxifolin can be regarded as potential drug candidates. A dose-dependent inhibition of MCF-7 cell growth was seen by the methanolic extract of holy basil with an IC50 value of 24.80 µg/mL thus establishing its antiproliferative activity. Considering the immense therapeutic abilities of holy basil, it was developed into hard candy lozenges with varying concentrations of holy basil (10%, 15%, 20%, 25%, 30% and 35%) ginger and amla extract. The organoleptic evaluation of the lozenges revealed that hard candy lozenges made with 30 % holy basil extract were more acceptable, owing to which the shelf life studies were done. The physicochemical evaluation of 100 g of the selected candy revealed that it had a moisture content of 2.78 per cent, protein content of 2.39 g, fat content of 0.67 g, ash content of 0.81 mg and energy content of 376.05 kcal. The moisture level of the candy increased but all other parameters, including protein, fat, ash content, and energy, were found to decrease throughout the three month storage period. The bacterial growth of the candy was seen to be within tolerable limits. Throughout the shelf-life period, no fungal or yeast growth was seen. Holy basil should be exploited endlessly for its restorative and curative properties. Currently, the herb is primarily used to make herbal tea and ayurvedic medicines. Apart from this, it can also be considered as a culinary herb, due to its potential natural antioxidant properties and its immense scope for development of value added products.