Isoprene-Degrading Bacteria from Soils Associated with Tropical Economic Crops and Framework Forest Trees

Isoprene, a volatile hydrocarbon emitted largely by plants, plays an important role in regulating the climate in diverse ways, such as reacting with free radicals in the atmosphere to produce greenhouse gases and pollutants. Isoprene is both deposited and formed in soil, where it can be consumed by some soil microbes, although much remains to be understood about isoprene consumption in tropical soils. In this study, isoprene-degrading bacteria from soils associated with tropical plants were investigated by cultivation and cultivation-independent approaches. Soil samples were taken from beneath selected framework forest trees and economic crops at different seasons, and isoprene degradation in soil microcosms was measured after 96 h of incubation. Isoprene losses were 4–31% and 15–52% in soils subjected to a lower (7.2 × 105 ppbv) and a higher (7.2 × 106 ppbv) concentration of isoprene, respectively. Sequencing of 16S rRNA genes revealed that bacterial communities in soil varied significantly across plant categories (framework trees versus economic crops) and the presence of isoprene, but not with isoprene concentration or season. Eight isoprene-degrading bacterial strains were isolated from the soils and, among these, four belong to the genera Ochrobactrum, Friedmanniella, Isoptericola and Cellulosimicrobium, which have not been previously shown to degrade isoprene

Genome characterisation of an isoprene-degrading Alcaligenes sp. isolated from a tropical restored forest

Isoprene is a climate-active biogenic volatile organic compound (BVOC), emitted into the atmosphere in abundance, mainly from terrestrial plants. Soil is an important sink for isoprene due to its consumption by microbes. In this study, we report the ability of a soil bacterium to degrade isoprene. Strain 13f was isolated from soil beneath wild Himalayan cherry trees in a tropical restored forest. Based on phylogenomic analysis and an Average Nucleotide Identity score of >95%, it most probably belongs to the species Alcaligenes faecalis. Isoprene degradation by Alcaligenes sp. strain 13f was measured by using gas chromatography. When isoprene was supplied as the sole carbon and energy source at the concentration of 7.2 × 105 ppbv and 7.2 × 106 ppbv, 32.6% and 19.6% of isoprene was consumed after 18 days, respectively. Genome analysis of Alcaligenes sp. strain 13f revealed that the genes that are typically found as part of the isoprene monooxygenase gene cluster in other isoprene-degrading bacteria were absent. This discovery suggests that there may be alternative pathways for isoprene metabolism

Efficacy of Kombucha Obtained from Green, Oolong, and Black Teas on Inhibition of Pathogenic Bacteria, Antioxidation, and Toxicity on Colorectal Cancer Cell Line

Kombucha tea is a refreshing beverage that is produced from the fermentation of tea leaves. In this study, kombucha tea was prepared using 1% green tea, oolong tea, and black tea, and 10% sucrose with acetic acid bacteria and yeast. The pH values of the kombucha tea were found to be in a range of 2.70–2.94 at 15 days of fermentation. The lowest pH value of 2.70 was recorded in the kombucha prepared from black tea. The total acidity of kombucha prepared from black tea was the highest by 16.75 g/L and it was still maintained after heat treatment by boiling and after autoclaved. Six organic acids: glucuronic, gluconic, D-saccharic acid 1,4-lactone, ascorbic, acetic, and succinic acid in kombucha tea were detected by HPLC with the optimization for organic acids detection using isocratic elution buffer with C18 conventional column. The highest level of organic acid was gluconic acid. Kombucha prepared from green tea revealed the highest phenolic content and antioxidation against DPPH radicals by 1.248 and 2.642 mg gallic acid/mL kombucha, respectively. Moreover, pathogenic enteric bacteria: Escherichia coli. E. coli O157:H7. Shigella dysenteriae, Salmonella Typhi, and Vibrio cholera were inhibited by kombucha and heat-denatured kombucha with diameter of the inhibition zones ranged from 15.0 ± 0.0–25.0 ± 0.0 mm. In addition, kombucha prepared from green tea and black tea demonstrated toxicity on Caco-2 colorectal cancer cells. Therefore, kombucha tea could be considered as a potential source of the antioxidation, inhibition of pathogenic enteric bacteria, and toxicity on colorectal cancer cells

Characterisation of Lactobacillus plantarum of Dairy-Product Origin for Probiotic Chèvre Cheese Production

Probiotics are increasingly used as functional food ingredients. The objectives of this study were to isolate and characterise probiotic bacteria from dairy and fermented foods and to use a selected strain for the production of probiotic chèvre cheese. Tolerance to acid (pH 2.0) and bile salt (0.4% (w/v)) were first investigated, and then other probiotic properties were determined. Out of 241 isolates, 35 showed high tolerance to acid and bile salt, and 6 were chosen for further characterisation. They were Lactobacillus plantarum and L. fermentum, and possessed antibacterial activities against foodborne pathogens such as Bacillus cereus, Staphylococcus aureus, Salmonella enterica and Escherichia coli O157:H7. L. plantarum (isolate AD73) showed the highest percentage of adhesion (81.74 ± 0.16%) and was nontoxic to Caco-2 cells at a concentration of 108 CFU/mL. This isolate was therefore selected for the production of probiotic chèvre cheese from goat’s milk and was prepared in a lyophilised form with a concentration of probiotic culture of 8.6 log CFU/g. The cheese had a shelf life of 8 days. On the expiry date, the probiotic, the starter and the yeast contents were 7.56 ± 0.05, 7.81 ± 0.03 and 5.64 log CFU/g, respectively. The level of the probiotics in this chèvre cheese was still sufficiently high to warrant its being a probiotic cheese

Antibiotic-Antiapoptotic Dual Function of Clinacanthus nutans (Burm. f.) Lindau Leaf Extracts against Bovine Mastitis

Mastitis caused by bacterial infection has negative impacts on milk quality and animal health, and ultimately causes economic losses to the dairy industry worldwide. Gram-negative bacteria and their component lipopolysaccharide (LPS) can trigger the inflammatory response of endothelial cells (ECs) and subsequently promote EC dysfunction or injury, which is a critical pathogenesis of mastitis-causing sepsis shock. To control the bacterial infection and to minimise the LPS negative effects on ECs, we thus aimed to identify the potential herb extracts that comprised antibacterial activity and protective ability to inhibit LPS-induced cell death. Extracts from seven types of herbs derived from antibacterial screening were investigated for their protective effects on LPS-stimulated bovine endothelial cell line. Clinacanthus nutans (Burm. f.) Lindau (C. nutans) extract appeared to be the most effective antiapoptotic extract against LPS stimulation. Treatment of C. nutans extract in LPS-stimulated cells significantly lowered apoptotic cell death through modulating pro-survival Bcl-2 and pro-apoptotic Bax expression. The investigation of bioactive compounds using solvent fractionation, HPLC, and LC-MS/MS analysis revealed glyceryl 1,3-disterate (C39H76O5), kaempferol 3-O-feruloyl-sophoroside 7-O-glucoside (C43H48O24), and hydroxypthioceranic acid (C46H92O3) as the candidate components. Our findings indicated that C. nutans extract has great potential to be further developed as an alternative therapeutic agent for mastitis treatment

Bacterial Communities Associated with Crude Oil Bioremediation through Composting Approaches with Indigenous Bacterial Isolate

In this study, we aim to investigate the efficiency of crude oil bioremediation through composting and culture-assisted composting. First, forty-eight bacteria were isolated from a crude oil-contaminated soil, and the isolate with the highest crude oil degradation activity, identified as Pseudomonas aeruginosa, was selected. The bioremediation was then investigated and compared between crude oil-contaminated soil (S), the contaminated soil composted with fruit-based waste (SW), and the contaminated soil composted with the same waste with the addition of the selected bacterium (SWB). Both compost-based methods showed high efficiencies of crude oil bioremediation (78.1% and 83.84% for SW and SWB, respectively). However, only a slight difference between the treatments without and with the addition of P. aeruginosa was observed. To make a clear understanding of this point, bacterial communities throughout the 4-week bioremediation period were analyzed. It was found that the community dynamics between both composted treatments were similar, which corresponds with their similar bioremediation efficiencies. Interestingly, Pseudomonas disappeared from the system after one week, which suggests that this genus was not the key degrader or only involved in the early stage of the process. Altogether, our results elaborate that fruit-based composting is an effective approach for crude oil bioremediation