Symbiotic bacteria can produce secondary metabolites and volatile compounds that contribute to amphibian skin defense. Some of these symbionts have been used as probiotics to treat or prevent the emerging disease chytridiomycosis. We examined 20 amphibian cutaneous bacteria for the production of prodigiosin or violacein, brightly colored defense compounds that pigment the bacteria and have characteristic spectroscopic properties making them readily detectable, and evaluated the antifungal activity of these compounds. We detected violacein from all six isolates of Janthinobacterium lividum on frogs from the USA, Switzerland, and on captive frogs originally from Panama. We detected prodigiosin from five isolates of Serratia plymuthica or S. marcescens, but not from four isolates of S. fonticola or S. liquefaciens. All J. lividum isolates produced violacein when visibly purple, while prodigiosin was only detected on visibly red Serratia isolates. When applied to cultures of chytrid fungi Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal), prodigiosin caused significant growth inhibition, with minimal inhibitory concentrations (MIC) of 10 and 50 μM, respectively. Violacein showed a MIC of 15 μM against both fungi and was slightly more active against Bsal than Bd at lower concentrations. Although neither violacein nor prodigiosin showed aerosol activity and is not considered a volatile organic compound (VOC), J. lividum and several Serratia isolates did produce antifungal VOCs. White Serratia isolates with undetectable prodigiosin levels could still inhibit Bd growth indicating additional antifungal compounds in their chemical arsenals. Similarly, J. lividum can produce antifungal compounds such as indole-3-carboxaldehyde in addition to violacein, and isolates are not always purple, or turn purple under certain growth conditions. When Serratia isolates were grown in the presence of cell-free supernatant (CFS) from the fungi, CFS from Bd inhibited growth of the prodigiosin-producing isolates, perhaps indicative of an evolutionary arms race; Bsal CFS did not inhibit bacterial growth. In contrast, growth of one J. lividum isolate was facilitated by CFS from both fungi. Isolates that grow and continue to produce antifungal compounds in the presence of pathogens may represent promising probiotics for amphibians infected or at risk of chytridiomycosis. In a global analysis, 89% of tested Serratia isolates and 82% of J. lividum isolates were capable of inhibiting Bd and these have been reported from anurans and caudates from five continents, indicating their widespread distribution and potential for host benefit.
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http://dx.doi.org/10.1007/s00248-017-1095-7 | DOI Listing |
Parasit Vectors
December 2024
Department of Biology, Georgia Southern University, 4324 Old Register Rd., Statesboro, GA, 30460, USA.
Background: Fleas are insect vectors that transmit several Gram-negative bacterial pathogens acquired by ingesting infected vertebrate blood. To combat foodborne illness, insect midgut epithelial cells are armed with efficient microbial recognition and control systems, such as the immune deficiency (IMD) pathway that regulates the expression of antimicrobial peptides (AMPs). However, despite their medical and veterinary importance, relatively little is known about the IMD signaling pathway and production of AMPs in the digestive tract of cat fleas (Ctenocephalides felis).
View Article and Find Full Text PDFAdv Biomed Res
October 2024
Department of Community Medicine, All India Institute of Medical Sciences, Mangalagiri, Andhra Pradesh, India.
Background: has emerged as an important nosocomial opportunistic pathogen, often associated with serious infections. We investigated the antimicrobial resistance trends, predisposing factors, and infection outcomes associated with isolated in a secondary-care hospital in Oman.
Materials And Methods: A retrospective study was conducted at a secondary-care hospital in the northern region of Oman after receiving approval from the research ethics and approval committee of Oman.
Cureus
November 2024
Microbiology, Kalinga Institute of Medical Sciences, Bhubaneswar, IND.
Background And Objectives: Stroke-associated pneumonia (SAP) is the aftermath of aspiration of oropharyngeal secretions or stomach content. Mechanical ventilation and lowered immunity and consciousness facilitate the etiopathogenesis of SAP. Antibiotic prophylaxis and repeated culture and sensitivity testing dampen the drug susceptibility patterns of the pathogens.
View Article and Find Full Text PDFInt Ophthalmol
December 2024
Department of Ophthalmology, University of Health Sciences, Ankara Bilkent City Hospital, Ankara, Turkey.
Purpose: To evaluate the role of Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, Serratia marcescens, and Moraxella catarrhalis in the nasal and ocular surface flora, along with their metabolic activities in children with unilateral congenital nasolacrimal duct obstruction (CNLDO).
Methods: Swabs were taken from the bilateral inferior meatus and ocular surface of 26 children with unilateral CNLDO before probing. Nasal and ocular surface swabs from non-operated eyes of children who underwent unilateral blepharoptosis or strabismus surgery formed the control group.
Environ Microbiome
December 2024
Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, Belgrade 152, 11042, Serbia.
Background: Herbicides are integral to agricultural weed management but can adversely affect non-target organisms, soil health, and microbiome. We investigated the effects of herbicides on the total soil bacterial community composition using 16S rRNA gene amplicon community profiling. Further, we aimed to identify herbicide-tolerant bacteria with plant growth-promoting (PGP) capabilities as a mitigative strategy for these negative effects, thereby promoting sustainable agricultural practices.
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