Isolation and identification of free-living amoebae isolated from well water in Istanbul

Free-living amoebae (FLA) are ubiquitous protozoa commonly found in water and soil environments. FLA belonging to various genera, including Acanthamoeba, Balamuthia, Naegleria, and Vermamoeba, can cause opportunistic and non-opportunistic infections in humans and animals such as keratitis or meningoencephalitis. In addition, some of them serve as hosts for a large number of pathogenic bacteria, yeasts, and viruses. The purpose of the present study was to assess the prevalence and molecular characterization of FLA in well water samples in İstanbul. Ten well water samples were collected from the taps and the presence of FLA was monitored both by the culture and polymerase chain reaction methods. FLA were isolated in 8 out of the 10 samples (80%) included in this study. Morphological analysis and partial sequencing of the 18S rDNA revealed the presence of Acanthamoeba genotypes T3 and T4, and Vermamoeba vermiformis in the investigated well water samples. This study reports for the first time the detection of Acanthamoeba genotype T3 in well water samples in İstanbul. The presence of potentially pathogenic amoebae in habitats related to human activities supports the relevance of FLA as a potential public health concern.

Occurrence of sulfate-reducing bacteria in well water: identification of anaerobic sulfidogenic bacterial enrichment cultures

Bacteriological studies of well water mainly focus on aerobic and facultative aerobic coliform bacteria. However, the presence of obligate anaerobic bacteria in well water, especially sulfate-reducing bacteria (SRB), possible causative agents of some diseases, is often ignored. In this study, the presence of SRB and coexisting anaerobic bacteria with SRB in sulfate-reducing enrichment cultures obtained from 10 well water samples in Istanbul was investigated. A nested polymerase chain reaction-denaturing gradient gel electrophoresis strategy was performed to characterize the bacterial community structure of the enrichments. The most probable number method was used to determine SRB number. Out of 10, SRB growth was observed in only one (10%) enrichment culture and the SRB number was low (<10 cells/mL). Community members were identified as Desulfolutivibrio sulfodismutans and Anaerosinus sp. The results show that SRB coexist with Anaerosinus sp., and this may indicate poor water quality, posing a risk to public health. Furthermore, Anaerosinus sp., found in the human intestinal tract, may be used as an alternative anaerobic fecal indicator. It is worth noting that the detection of bacteria using molecular analyzes following enrichment culture techniques can bring new perspectives to determine the possible origin and presence of alternative microbial indicators in aquatic environments.

Facivitalis istanbulensis gen. nov., sp. nov., a novel member of the family Sphingomonadaceae with the potential for aromatic-degradation isolated from Jet A1 fuel

A novel gram-stain-indeterminate, rod-shaped, endospore-forming, motile, aerobic bacterium, designated JETA1-E2T, was isolated from aircraft fuel Jet A1 sample. The strain showed high pairwise similarity values of partial 16S rRNA gene sequences to Sphingomonas paucimobilis (MT367853) (99.42%), Sphingomonas sanguinis (MF319771) (99.34%), and Sphingomonas pseudosanguinis (HE716953) (99.27%) within the family Sphingomonadaceae. However, API test results revealed that the strain JETA1-E2T differed from these type strains. The phylogenetic tree based on the whole genome and the phylogenomic tree generated with the UBCG tool showed that the strain JETA1-E2T formed a distinct monophyletic clade within the family Sphingomonadaceae, and clustered distantly with the genera Sphingomonas and Sphingobium. The predominant respiratory quinone is Q-10. The major fatty acids are C16:0 and summed feature 8 (C18:1ω7c and/or C18:1ω6c). C19:0 is present in small amounts. The polar lipids are diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, aminophospholipid, unidentified glycolipid, and two unidentified sphingoglycolipids. The only polyamine is putrescine in minor amounts. The DNA G + C content of the type strain is 66.5 mol%. Several unique genes in the strain JETA1-E2T may contribute to fight against various stressors, virulence and pathogenicity, as well as survival in challenging conditions. The strain JETA1-E2T contains 100 of the characterised proteins available in the HADEG database of which 58% of these are involved in metabolic process of aromatics degradation. The findings indicate that the strain JETA1-E2T has the potential to metabolise hydrocarbons such as fuel, especially aromatic compounds. Based on the results of polyphasic taxonomic analyses, the strain JETA1-E2T represents a novel species in a new genus in the family Sphingomonadaceae for which the name Facivitalis istanbulensis gen. nov., sp. nov. is proposed. The type strain of Facivitalis istanbulensis is JETA1-E2T (DSM 117971T = LMG 33634T = KUEN 1206 (B) F3-1-1T).