Inactivation of the core cheVAWY chemotaxis genes disrupts chemotactic motility and organised biofilm formation in Campylobacter jejuni

Flagellar motility plays a central role in the bacterial foodborne pathogen Campylobacter jejuni, as flagellar motility is required for reaching the intestinal epithelium and subsequent colonisation or disease. Flagellar proteins also contribute strongly to biofilm formation during transmission. Chemotaxis is the process directing flagellar motility in response to attractant and repellent stimuli, but its role in biofilm formation of C. jejuni is not well understood. Here we show that inactivation of the core chemotaxis genes cheVAWY in C. jejuni strain NCTC 11168 affects both chemotactic motility and biofilm formation. Inactivation of any of the core chemotaxis genes (cheA, cheY, cheV or cheW) impaired chemotactic motility but did not affect flagellar assembly or growth. The ∆cheY mutant swam in clockwise loops, while complementation restored normal motility. Inactivation of the core chemotaxis genes interfered with the ability to form a discrete biofilm at the air-media interface, and the ∆cheY mutant displayed reduced dispersal/shedding of bacteria into the planktonic fraction. This suggests that while the chemotaxis system is not required for biofilm formation per se, it is necessary for organized biofilm formation. Hence interference with the Campylobacter chemotaxis system at any level disrupts optimal chemotactic motility and transmission modes such as biofilm formation.

Klebsiella indica sp. nov., isolated from the surface of a tomato

A novel bacterial strain, designated TOUT106T, was isolated from the surface of a tomato. The cells were rod-shaped, Gram-negative, encapsulated and non-motile. Strain TOUT106T grows best at 28 °C and pH 7.0 and can tolerate up to 2 % (w/v) NaCl. Based on 16S rRNA gene phylogeny, strain TOUT106T was placed close to the Salmonella clade, with close similarity to Salmonella enterica subsp. arizonae strain NCTC 8297T (98.42 %). Results of genome-based phylogenetic analysis revealed that strain TOUT106T is placed well in the Klebsiella–Raoultella clade, by forming a distinct branch with Klebsiella michiganensis DSM25444T, Klebsiella oxytoca NCTC132727T, Klebsiella grimontii 06D021T and Klebsiella pasteurii SB6412T. The genomic DNA G+C content of strain TOUT106T is 53.53 mol%. The average nucleotide identity values of TOUT106T were less than 86.5 % with closely related members of the family Enterobacteriaceae . The major fatty acids of strain TOUT106T were C16 : 0, C17:0 cyclo, C14:0 3OH/C16:1 iso, C14 : 0, C19:0 cyclo ω8c, C18:1 ω6c/C18:1 ω7c, C12 : 0 and C16:1 ω7c/C16:1 ω6c. Strain TOUT106T showed differences in physiological, phenotypic and protein profiles by MALDI-TOF MS compared to its closest relatives. Based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, strain TOUT106T could be distinguished from the recognized species of the genus Klebsiella . It is suggested to represent a novel species of this genus, for which the name Klebsiella indica sp. nov. is proposed. The type strain is TOUT106T (=MCC 2901T=KACC 21384T=JCM 33718T).

Corynebacterium Diphtheriae: A Case Report of Some Isolates in National Ear Care Centre Kaduna

This is a case study of the incidence of diphtheria in National Ear Care Centre Kaduna. Samples included all patients presented with diphtheria symptoms referred to the hospital from October to December; 2018. A total of 8 patients were referred and several samples taken for laboratory investigations. 8 throat swabs were collected for organism isolation by inoculation on some certain agars, incubation, secondary gram and microscopy; colonies appeared to be biconcave, large and whitish. Microscopy revealed characteristic Chinese lettered, pleomorphic bacillus which are features of Corynebacterium diphtheriae. Blood samples were used for urea and creatinine estimation which yielded abnormal high values in all except the creatinine of one of the samples indicating kidney impairment which could be attributed to presence of the tox gene. To further confirm the incidence of the disease; one throat swab was saved at 4°C for molecular confirmation and characterisation of the gene. It was then transported to Molecular laboratory and the DNA extracted using the phenol/chloroform extraction method. Both the A and B subunits of the tox gene were amplified from the DNA extract at 248bp and 297bp respectively. Sanger’s Dye Terminator Cycle Sequencing (DTCS) of both the subunits of the tox gene was carried out and the sequences were obtained and converted to the fasta format using a Finch TV for bioinformatics analyses using the NCBI blast tool. The A and B subunits showed a percentage identity of 99.59% and 95.57% to Corynebacterium diphtheriae mitis strain NCTC 3529 genome assembly, chromosome: 1 respectively. The A subunit also showed 99.59% identity to Corynebacterium diphtheriae strain BQ11 chromosome; complete genome while the B subunit also showed 95.57% identity to Corynebacterium diphtheriae mitis strain NCTC 7838 genome assembly chromosome: 1. A mutation was also discovered in the tox genes as indicated by the E-value of 3e-84 and 2e-121 for A and B subunits respectively which are values that are less than 1. This is also confirmed by 5 gaps noticed from the blast results (4 gaps from A and 1 from B) indicating the presence of indels. In conclusion; there are confirmed incidences and sporadic cases of diphtheria in Kaduna State and the organism is said to have mutated.

Description of Klebsiella indica sp. nov., isolated from the surface of tomato

A novel bacterial strain designated TOUT106T was isolated from the surface of a tomato collected from the local vegetable market in Pune, India. The cells were rod shaped, Gram-stain-negative, encapsulated and non-motile. The strain TOUT106T grows as mucoid and translucent colonies on blood agar medium and the best growth was observed at 28°C and at pH 7.0, and could tolerate up to 2% (w/v) NaCl. On the basis of 16S rRNA gene sequence analysis, strain TOUT106T was placed under Salmonella clade, with close similarity to Salmonella enterica subsp. arizonae strain NCTC 8297T (98.42%). Genome-based phylogenetic analysis revealed that the strain forms a distinct branch within the Klebsiella clade and K. michiganensis DSM25444T and K. oxytoca NBRC105695T were the closest neighbor. The genomic DNA G+C content of strain TOUT106T was 53.53 mol%. The average nucleotide identity of TOUT106T was less 86.4% with closely related members of the family Enterobacteriaceae. The major fatty acids of strain TOUT106T were C16:0, C17:0 cyclo, C14:0 3OH/C16:1 iso, C14:0, C19:0cyclow8c, C18:1 w6c/C18:1 w7c, C12:0 and C16:1 w7c/C16:1 w6c. The strain TOUT106T showed differences in physiological, phenotypic and protein profiles by MALDI-TOF MS to its closest relatives. Based on the phenotypic including chemotaxonomic properties and phylogenetic analysis the strain TOUT106T could be distinguished from the recognized species of the genus Klebsiella, was suggested to represent a novel species of this genus, for which the name Klebsiella indica sp. nov. is proposed. The type strain is TOUT106T (=MCC 2901T).

Complete Whole-Genome Sequence of Haemophilus haemolyticus NCTC 10839

Haemophilus haemolyticus is a Gram-negative bacterium that is a commensal of the respiratory tract in humans. Here, we report the complete genome sequence available for Haemophilus haemolyticus strain NCTC 10839, which was originally isolated from the nasopharynx of a child.

Inactivation of the core cheVAWY chemotaxis genes disrupts chemotactic motility and organised biofilm formation in Campylobacter jejuni

ABSTRACTFlagellar motility plays a central role in the bacterial foodborne pathogen Campylobacter jejuni, as flagellar motility is required for reaching the intestinal epithelium and subsequent colonisation or disease. Flagellar proteins also contribute strongly to biofilm formation during transmission. Chemotaxis is the process directing flagellar motility in response to attractant and repellent stimuli, but its role in biofilm formation of C. jejuni is not well understood. Here we show that inactivation of the core chemotaxis genes cheVAWY in C. jejuni strain NCTC 11168 affects both chemotactic motility and biofilm formation. Inactivation of any of the core chemotaxis genes (cheA, cheY, cheV or cheW) impaired chemotactic motility but did not affect flagellar assembly or growth. The ΔcheY mutant swam in clockwise loops, while complementation restored normal motility. Inactivation of the core chemotaxis genes interfered with the ability to form a discrete biofilm at the air-media interface, and the ΔcheY mutant displayed reduced dispersal/shedding of bacteria into the planktonic fraction. This suggests that while the chemotaxis system is not required for biofilm formation per se, it is necessary for organized biofilm formation. Hence interference with the Campylobacter chemotaxis system at any level disrupts optimal chemotactic motility and transmission modes such as biofilm formation.