Effect of mineral fertilizer, pig manure, and Azospirillum rugosum on growth and nutrient contents of Lactuca sativa L

Benefits from the application of plant growth-promoting bacteria in agriculture largely depend on the complex interactions between several factors including the nature of fertilizers selected. This study was designed to determine the fine tuning between the inoculated bacteria and different fertilizers and their effect on the growth of lettuce plants (Lactuca sativa L.). Plant growth promotion by a novel species of the genus Azospirillum, namely A. rugosum IMMIB AFH-6, was tested by biochemical, bioassay, and greenhouse studies. The treatments used in the greenhouse study were; unfertilized control (Blank), half recommended dose of chemical fertilizer (1/2CF), full recommended dose of chemical fertilizer (1CF), pig manure fertilizer (PMF), pig manure fertilizer + half recommended dose of chemical fertilizer (PMF + 1/2CF), and pig manure fertilizer + full recommended dose of chemical fertilizer (PMF + 1CF). All these treatments when inoculated with A. rugosum IMMIB AFH-6 inoculation were, respectively, In-Blank, In-1/2CF, In-1CF, In-PMF, In-PMF + 1/2CF, and In-PMF + 1CF. Significant increase in plant biomass and shoot N, P, Ca, and Fe was shown in the In-Blank treatment. Plant growth in soil amended with PMF and A. rugosum IMMIB AFH-6 was significantly lower than in soil treated with the chemical fertilizer, but inoculation combined with chemical fertilizer significantly elevated the plant biomass. The In-PMF + 1/2CF treatment showed the highest yield. A. rugosum IMMIB AFH-6 facilitated the accumulation of trace minerals in higher concentrations when PMF was combined with 1CF. To examine the benefits of inoculation by A. rugosum IMMIB AFH-6, we have proposed a new type of data analysis which considers both biomass and nutrient content of plants. This new type of analysis has shown the importance of the mineral content of plant

Transfer of Flexibacter sancti, Flexibacter filiformis, Flexibacter japonensis and Cytophaga arvensicola to the genus Chitinophaga and description of Chitinophaga skermanii sp nov

Analysis of the 16S rRNA gene sequences of species currently assigned to the genus Flexibacter has shown extensive intrageneric phylogenetic heterogeneity. It has been shown in previous studies that the species [Flexibacter] sancti, [Flexibacter] filiformis and [Flexibacter] japonensis were most closely related to Chitinophaga pinensis. In addition, [Cytophaga] arvensicola and species of the genus Terrimonas also clustered into this phylogenetic group. Although the similarities of 16S rRNA gene sequences were low (88.5-96.4%), there is no evidence for clear phenotypic differences between these organisms that justify assignment to different genera. A proposal is made to transfer these species to the genus Chitinophaga as Chitinophaga sancti comb. nov., Chitinophaga filiformis comb. nov., Chitinophaga japonenis comb. nov. and Chitinophaga arvensicola comb. nov. on the basis of phylogenetic and phenotypic data. Furthermore, a novel species is described within this genus, Chitinophaga skermanii sp. nov., with strain CC-SG1B(T) (=CCUG 52510(T)=CIP 109140(T)) as the type strain

Deinococcus ficus sp nov., isolated from the rhizosphere of Ficus religiosa L

A pale-pink strain (CC-FR2-10(T)) from the rhizosphere of the sacred tree Ficus religiosa L. in Taiwan was investigated by using a polyphasic taxonomic approach. The cells were Gram-positive, rod-shaped and non-spore-forming. Phylogenetic analyses using the 16S rRNA gene sequence of the isolate indicated that the organism belongs to the genus Deinococcus, the highest sequence similarities being found with Deinococcus grandis (96.1%), Deinococcus radiodurans (94.3%),Deinococcus radiopugnans (93.2%), Deinococcus indicus (93.0%), Deinococcus proteolyticus (92.5%), Deinococcus murrayi (92.4%) and Deinococcus geothermalis (90.7%). The DNA-DNA relatedness with respect to D. grandis DSM 3963(T) was 17.9%. Chemotaxonomic data revealed that strain CC-FR2-10(T) contains only menaquinone MK-8 as the respiratory quinone, unknown phosphoglycolipids as the predominant polar lipids and 16:1 omega 7c, 17:1 omega 8c and 17:1 omega 9c iso as the predominant fatty acids. The biochemical and chemotaxonomic properties demonstrate that strain CC-FR2-10(T) represents a novel species, for which the name Deinococcus ficus sp. nov. is proposed. The type strain is CC-FR2-10(T) (= CCUG 53391(T) = CIP 108832(T))

Zeaxanthin Biosynthesis by Members of the Genus Muricauda

Zeaxanthin, a C40xanthophyll carotenoid, has potential biological applications in nutrition and human health. In this study we characterized carotenoid composition in 5 taxonomically related marine bacterial isolates from the genus Muricauda. The pigment was characterized using high performance liquid chromatography (HPLC) and mass spectrometry, which confirmed the presence of all-trans-zeaxanthin. Muricauda strains produced zeaxanthin as a predominant carotenoid. M. flavescens JCM 11812(T) produced highest yield (4.4 +/- 0.2 mg L(-1)) when cultured on marine broth at 32 degrees C for 72 h. This is the first report on the presence of zeaxanthin among the majority of species from the genus Muricauda.</jats:p

Anti-quorum sensing activity of flavonoid-rich fraction from Centella asiatica L. against Pseudomonas aeruginosa PAO1

Background/PurposeInhibition of quorum sensing (QS), a cell-density dependent regulation of gene expression in bacteria by autoinducers is an attractive strategy for the development of antipathogenic agents.MethodsIn this study, the anti-QS activity of the ethanolic extract of the traditional herb Centella asiatica was investigated by the biosensor bioassay using Chromobacterium violaceum CV026. The effect of ethyl acetate fraction (CEA) from the bioassay-guided fractionation of ethanol extract on QS-regulated violacein production in C. violaceum ATCC12472 and pyocyanin production, proteolytic and elastolytic activities, swarming motility, and biofilm formation in Pseudomonas aeruginosa PAO1 were evaluated. Possible mechanism of QS-inhibitory action on autoinducer activity was determined by measuring the acyl homoserine lactone using C. violaceum ATCC31532. Anti-QS compounds in the CEA fraction were identified using thin layer chromatography biosensor overlay assay.ResultsEthanol extract of C. asiatica showed QS inhibition in C. violaceum CV026. Bioassay-guided fractionation of ethanol extract revealed that CEA was four times more active than the ethanol extract. CEA, at 400 μg/mL, completely inhibited violacein production in C. violaceum ATCC12472 without significantly affecting growth. CEA also showed inhibition of QS-regulated phenotypes, namely, pyocyanin production, elastolytic and proteolytic activities, swarming motility, and biofilm formation in P. aeruginosa PAO1 in a concentration-dependent manner. Thin layer chromatography of CEA with biosensor overlay showed anti-QS spot with an Rf value that corresponded with that of standard kaempferol.ConclusionThe anti-QS nature of C. asiatica herb can be further exploited for the formulation of drugs targeting bacterial infections where pathogenicity is mediated through QS