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Quorum Sensing and Essential Oils
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Isabel Charlotte Soede, Gerhard Buchbauer
Whereas Solano et al. believe that QS is most reasonable in the last step of biofilm disassembly, as the signal density reaches sufficient concentrations only then (Solano and Echeverz, 2014), research has shown that QS influences all stages of biofilm formation (Parsek and Greenberg, 2005). In human pathogens Staphylococcus aureus (Yarwood and Schlievert, 2003), Helicobacter pylori (Cole et al., 2004), and Salmonella enterica (Prouty et al., 2002) QS plays a role in the attachment phase of biofilm formation (Costerton et al., 1995). An example for an AHL-based QS system responsible for biofilm maturation is Aeromonas hydrophila (Lynch et al., 2002). Lynch et al. found out that the plant pathogen Xanthomonas campestris uses a QS system which is involved in biofilm dispersal (Lynch et al., 2002).
Beneficial Lactic Acid Bacteria
Published in K. Balamurugan, U. Prithika, Pocket Guide to Bacterial Infections, 2019
Some experiments concerned the use of LAB in treatment of plant diseases. Plant pathogen Ralstonia solanacearum causes bacterial wilt. Lactobacillus sp. strain KLF01 isolated from rhizosphere of tomato reduced disease severity of tomato and red pepper as compared to nontreated plants (Shrestha et al. 2009a). Lactobacillus KLF01 and Lactococcus KLC02 strains showed 55% and 60% bio-control efficacy, respectively, in regard to Pectobacterium carotovorum subsp. carotovorum, soft rot pathogen, on Chinese cabbage (Shrestha et al. 2009b). These LAB significantly reduced bacterial spot caused by Xanthomonas campestris pv. vesicatoria on pepper plants in comparison with untreated plants in both greenhouse and field experiments. Additionally, LAB are able to colonize roots, produce indole-3-acetic acid, siderophores, and solubilize phosphates (Shrestha et al. 2014). LAB are effective in the removal of the root-knot nematodes. The decreased pH levels in agricultural soil due to lactic acid produced by bacteria are correlated with reduced population of nematodes (Takei et al. 2008). Microalgae are used as feed for live prey (rotifers, Artemia), larvae and adult fish, mollusks, and crustaceans. The growth of microalgae Isochrysis galbana was enhanced by LAB, both in the absence and in the presence of nutrients in the culture. The highest final biomass concentration was achieved by adding Pediococcus acidilactici, whereas Leuconostoc mesenteroides spp. mesenteroides and Carnobacterium piscicola provided for maximal growth rates. However, the latter species also showed inhibitory effect on Moraxella (Planas et al. 2015).
Potential of Syzygium cumini for Biocontrol and Phytoremediation
Published in K. N. Nair, The Genus Syzygium, 2017
S. K. Tewari, R. C. Nainwal, Devendra Singh
Various workers have identified the pesticidal activity of S. cumini against several pathogens and insects. Extract from bark and leaves of S. cumini decreased local lesion production by turnip mosaic virus in Chenopodium amaranticolor within four hours of application in preinoculation treatments (Pandey and Mohan 1986). The methanolic extract of S. cumini showed maximum inhibitory effect against Xanthomonas campestris (Uma et al. 2012). Sunder et al. (2005) examined the effect of a crude extract of fruit of S. cumini against bacterial blight pathogen (Xanthomonas oryzae pv. oryzae) of rice in field trials in Haryana, India, during kharif and found that the extract decreased both the severity and incidence of the disease significantly. It showed antifungal activity against Trichophyton tonsurans, T. rubrum, T. simii, T. beigelii, Microsporum fulvum, and M. gypseum. Gupta and Bhadauria (2012) studied the antifungal potential of aqueous extracts of leaves, bark, seeds, and fruits of S. cumini against two important fungal plant pathogens, Alternaria alternata and Fusarium oxysporum. Results revealed that among various plant parts, aqueous extract of fruit was most effective against the growth of F. oxysporum compared with other extracts, whereas the aqueous extract of bark showed potential to inhibit the growth of A. alternata. The extract of leaves was not found to be very effective against both test organisms. Arshad and Samad (2012) studied the antifungal activity of methanolic extracts of leaves of S. cumini against two strains of A. alternata, isolated from dying-back trees. The methanolic extract significantly reduced the fungal biomass. There were reductions in the range of 82%–88% in the biomass of A. alternata strains due to different concentrations of the leaf extracts of S. cumini. The study concluded that aqueous and n-butanol fractions of methanolic leaf extract of S. cumini could be used as biofungicides for the management of A. alternata.
Bacterial ι-carbonic anhydrase: a new active class of carbonic anhydrase identified in the genome of the Gram-negative bacterium Burkholderia territorii
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Sonia Del Prete, Alessio Nocentini, Claudiu T. Supuran, Clemente Capasso
To date, no X-ray crystallographic or NMR structures are available for ι-CA and, as obtaining them is an intricate and time consuming process. However, the computational approach to predict protein three-dimensional structures starting from the amino acid sequence is an appealing alternative. Thus, using a fully automated protein homology modelling server SWISS-MODEL (https://swissmodel.expasy.org), we generated a raw first model of the bacterial BteCAι. The automated mode selects the structural templates that maximise the expected quality of the model. Two main templates were identified with a 50% identity (the other templates showed an identity ranging from 16 to 27%). Surprisingly, all the templates were identified as putative calcium/calmodulin-dependent protein kinase II Association Domain. We focalised our attention on the first template homologous to BteCAι and coming from Xanthomonas campestris, a bacterial species that causes a variety of plant diseases70. Its PDB code is 3h51, while NP_636218.1 is the protein accession number. Astonishingly, the code NP_6362218.1 (now WP_011036063.1 in the Pubmed (https://www.ncbi.nlm.nih.gov/protein/WP_011036063.1)) corresponded to a sequence classified as SgcJ/EcaC family oxidoreductase, which is the annotation of most of the sequences found during the search of the bacterial ι-CAs in the data bank. This prompt us to align the amino acid sequence of BteCAι with that identified in X. campestris (Figure 8, Panel A). The ι-CA amino acid sequences identified in B. territorii displays a 42% identity with the X. campestris amino acid sequence (38%identity with LCIP63 domain), and, as expected, the typical ι-CA consensus “HHHSS” at the C-terminus of the polypeptide chain is present (Figure 8, Panel A). In Figure 8, Panel B, we report the generated model of BteCAι with the consensus histidines of each monomer highlighted in red. We want stress that the resulting model predicted a dimeric organisation of the protein. This confirms the results obtained from the protonography performed at different concentration of SDS, which evidenced the presence of an hydratase activity at a molecular weight of 40.0 kDa (enzyme dimeric state). Of course, work is in progress for obtaining the crystal structure of BteCAι especially for understanding the coordination of the catalytic ion cofactor, if Zn2+, Mn2+ or another metal ion, as well as the metal coordination pattern.