Overgrazing-induced legacy effects may permit Leymus chinensis to cope with herbivory

There is growing evidence that herbivory-induced legacy effects permit plants to cope with herbivory. However, herbivory-induced defense strategies in plants against grazing mammals have received little attention. To further understand the grazing-induced legacy effects on plants, we conducted a greenhouse experiment with Leymus chinensis experiencing different grazing histories. We focused on grazing-induced legacy effects on above-ground spatial avoidance and below-ground biomass allocation. Our results showed that L. chinensis collected from the continuous overgrazing plot (OG) exhibited higher performance under simulated grazing in terms of growth, cloning and colonizing ability than those collected from the 35-year no-grazing plot (NG). The enhanced adaptability of OG was attributed to increased above-ground spatial avoidance, which was mediated by larger leaf angle and shorter height (reduced vertical height and increased leaf angle contributed to the above-ground spatial avoidance at a lower herbivory stubble height, while reduced tiller natural height contributed to above-ground spatial avoidance at a higher herbivory stubble height). Contrary to our prediction, OG pre-allocated less biomass to the rhizome, which does not benefit the herbivory tolerance and avoidance of L. chinensis; however, this also may reflect a tolerance strategy where reduced allocation to rhizomes is associated with increased production of ramets.

Competitive exclusion of uropathogenic E. coli biofilm by Salmonella through matrix inhibition

SummaryBiofilm is a predominant lifestyle of bacteria in host and non-host environments with cell collectives and extracellular matrix as the defining principles of biofilm. Several factors trigger biofilm formation including response to competition. Urinary tract infections (UTI) are highly prevalent worldwide and mainly caused by uropathogenic E. coli (UPEC), which progresses into chronic form due to the biofilm formation by the pathogen. In this study, we hypothesized that competition for territorial space could occur between species by intervening in the biofilm matrix production, particularly of UPEC, thereby reducing its colonizing ability. UPEC colony displays different morphology in congo red media based on matrix production, which we exploited for screening bacterial isolates capable of inhibiting the matrix. This was validated by using the cell-free supernatants of the isolates to impair UPEC biofilm. Isolates that inhibited matrix production belonged to species of Shigella, Escherichia, Enterobacter, and Salmonella from Enterobacteriaceae family. Competition experiments between the isolates and UPEC revealed spiteful interactions particularly during biofilm formation, indicating fierce competition for territorial space colonization. The isolate Salmonella enterica B1 could competitively exclude UPEC in the biofilm. Altogether, we show that interference competition by matrix inhibition occurs as a strategy by bacteria to colonize territorial space.

Features of the microbial landscape in purulent-inflammatory pathologies in dogs

Microbiota studies in pyoin-flammatory pathologies in small pets determine an effective treatment strategy. Pyogenic pathogens – participants in inflammatory processes of the skin and its derivatives, mucous membranes and wound surfaces have high adaptive properties, colonizing ability, high antibiotic resistance. The article presents data on the study of the qualitative composition of the microflora that causes purulent-inflammatory pathology in dogs, determines the biological and biochemical properties of the isolated microorganisms, the pathogenicity of cultures. An analysis of the antibiotic resistance of the isolated microorganisms was carried out, and on this basis, a treatment regimen was applied.

Effects of Weissella cibaria CMU on Halitosis and Calculus, Plaque, and Gingivitis Indices in Beagles

Weissella (W.) cibaria strain Chonnam Medical University (CMU) has shown oral colonizing ability and inhibitory effects on the formation of volatile sulfur compounds (VSCs) in vitro studies. The present study was conducted to analyze the effects of the W. cibaria CMU on canine oral health. Halitosis, calculus, plaque, gingivitis, and intraoral microbiota were assessed in 3 groups: control (maltodextrin), W. cibaria CMU low concentration (CMU-L, 2 × 107 colony forming unit [CFU]), and high-concentration (CMU-H, 2 × 109 CFU). Halitosis was analyzed using both organoleptic evaluation and measurement of VSCs. Intraoral microbiota were analyzed by real-time polymerase chain reaction. From week 4, the total VSC level in the CMU-H group (4.0 ± 1.30 ng/10 mL) was significantly lower than in the control group (6.3 ± 2.28 ng/10 mL). Significant reduction in methyl mercaptan in the CMU-treated groups was also observed. In addition, the plaque index in the CMU-treated groups was significantly decreased. The CMU-treated groups showed significant decreases in Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythia and demonstrated the colonizing ability of W. cibaria CMU in the oral cavity. We demonstrated that W. cibaria CMU suppresses halitosis, colonizes the oral cavity, and inhibits the proliferation of malodor-causing oral bacteria in beagles. According to these results, we expect that W. cibaria CMU could be a new oral hygiene solution by reducing VSC production and inhibiting the growth of oral harmful bacteria in companion animals.

Determination of the In vitro Effect of Trichoderma harzianum on Phytopathogenic Strains of Fusarium oxysporum

Fusarium oxysporum is a well-known soil-borne fungi and it is difficult to control their pathogenic strains by conventional strategies. The cultures of two strains of Trichoderma harzianum (T16 and T23) were examined in laboratory conditions and with pot experiments for the control of pathogenic strains of Fusarium oxysporum f. sp. melongenae (Fomg), Fusarium oxysporum f. sp. lycopersici (Fol), Fusarium oxysporum f. sp. niveum (Fon) and F. oxysporum f. sp. melonis (Fom). The T16 and T23 strains showed significant inhibition of mycelial growth in the pathogenic strains of F. oxysporum and the maximum inhibition were recorded when the T. harzianum strain T16 was used (72.69%). Both T. harzianum strains produced volatile and non-volatile metabolites that inhibited growth of F. oxysporum strains on PDA medium. In vitro colonization study demonstrated the root-colonizing ability of these antagonists. The interaction between T. harzianum isolates (T16 and T23) and pathogenic F. oxysporum hyphae showed no overgrowth, hyphal coiling, cell wall degradation or any hyphal penetration around any of the tested F. oxysporum hyphae. Pre-treatment of soil with T16 significantly reduced the severity of Fusarium wilt disease. The disease severity in control plants reached to 90-95% whereas those of the T16-Fomg and T16-Fol treated seedlings of eggplants were 37.74% and 47.12%, respectively, on the 21st day. In this study, while both T. harzianum isolates had a considerable antagonistic effect on the tested pathogens, T16 was found to be more successful than T23. The strong repressive effect of T. harzianum (T16) towards pathogenic Fusarium oxsporum can be applied in biological control of these pathogens.