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Lysogenicity of the strains of Vibrio cholerae, biotype eltor recently isolated in various countries

Ohashi M, Terayama T, Ushioda H, Kudoh Y, Tsuno M, Sakai S

Microbiol. Immunol., 1981;25(6):613-6.
PMID: 7278707
Matched MeSH terms: Bacteriophages/physiology*
Isolation and characterization of lytic vibriophage against Vibrio cholerae O1 from environmental water samples in Kelantan, Malaysia

Al-Fendi A, Shueb RH, Ravichandran M, Yean CY

J Basic Microbiol, 2014 Oct;54(10):1036-43.
PMID: 24532381 DOI: 10.1002/jobm.201300458

Water samples from a variety of sources in Kelantan, Malaysia (lakes, ponds, rivers, ditches, fish farms, and sewage) were screened for the presence of bacteriophages infecting Vibrio cholerae. Ten strains of V. cholerae that appeared to be free of inducible prophages were used as the host strains. Eleven bacteriophage isolates were obtained by plaque assay, three of which were lytic and further characterized. The morphologies of the three lytic phages were similar with each having an icosahedral head (ca. 50-60 nm in diameter), a neck, and a sheathed tail (ca. 90-100 nm in length) characteristic of the family Myoviridae. The genomes of the lytic phages were indistinguishable in length (ca. 33.5 kb), nuclease sensitivity (digestible with DNase I, but not RNase A or S1 nuclease), and restriction enzyme sensitivity (identical banding patterns with HindIII, no digestion with seven other enzymes). Testing for infection against 46 strains of V. cholerae and 16 other species of enteric bacteria revealed that all three isolates had a narrow host range and were only capable of infecting V. cholerae O1 El Tor Inaba. The similar morphologies, indistinguishable genome characteristics, and identical host ranges of these lytic isolates suggests that they represent one phage, or several very closely related phages, present in different water sources. These isolates are good candidates for further bio-phage-control studies.

Matched MeSH terms: Bacteriophages/physiology*
Fulltext Engineering integrative vectors based on phage site-specific recombination mechanism for Lactococcus lactis

Koko I, Song AA, Masarudin MJ, Abdul Rahim R

BMC Biotechnol, 2019 11 27;19(1):82.
PMID: 31775775 DOI: 10.1186/s12896-019-0575-x

BACKGROUND: Site-specific integration system allows foreign DNA to be integrated into the specific site of the host genome, enabling stable expression of heterologous protein. In this study, integrative vectors for secretion and surface display of proteins were constructed based on a lactococcal phage TP901-1 integrating system.
RESULTS: The constructed integration system comprises of a lactococcal promoter (PnisA or P170), phage attachment site (attP) from bacteriophage TP901-1, a signal peptide (USP45 or SPK1) for translocation of the target protein, and a PrtP344 anchor domain in the case of the integrative vectors for surface display. There were eight successfully constructed integrative vectors with each having a different combination of promoter and signal peptide; pS1, pS2, pS3 and pS4 for secretion, and pSD1, pSD2, pSD3 and pSD4 for surface display of desired protein. The integration of the vectors into the host genome was assisted by a helper vector harbouring the integrase gene. A nuclease gene was used as a reporter and was successfully integrated into the L. lactis genome and Nuc was secreted or displayed as expected. The signal peptide SPK1 was observed to be superior to USP45-LEISSTCDA fusion in the secretion of Nuc. As for the surface display integrative vector, all systems developed were comparable with the exception of the combination of P170 promoter with USP45 signal peptide which gave very low signals in whole cell ELISA.
CONCLUSION: The engineered synthetic integrative vectors have the potential to be used for secretion or surface display of heterologous protein production in lactococcal expression system for research or industrial purposes, especially in live vaccine delivery.

Matched MeSH terms: Bacteriophages/physiology*
Fulltext Klebsiella virus UPM2146 lyses multiple drug-resistant Klebsiella pneumoniae in vitro and in vivo

Assafiri O, Song AA, Tan GH, Hanish I, Hashim AM, Yusoff K

PLoS One, 2021;16(1):e0245354.
PMID: 33418559 DOI: 10.1371/journal.pone.0245354

Klebsiella pneumoniae are opportunistic bacteria found in the gut. In recent years they have been associated with nosocomial infections. The increased incidence of multiple drug-resistant K. pneumoniae makes it necessary to find new alternatives to treat the disease. In this study, phage UPM2146 was isolated from a polluted lake which can lyse its host K. pneumoniae ATCC BAA-2146. Observation from TEM shows that UPM2146 belongs to Caudoviriales (Order) based on morphological appearance. Whole genome analysis of UPM2146 showed that its genome comprises 160,795 bp encoding for 214 putative open reading frames (ORFs). Phylogenetic analysis revealed that the phage belongs to Ackermannviridae (Family) under the Caudoviriales. UPM2146 produces clear plaques with high titers of 1010 PFU/ml. The phage has an adsorption period of 4 min, latent period of 20 min, rise period of 5 min, and releases approximately 20 PFU/ bacteria at Multiplicity of Infection (MOI) of 0.001. UPM2146 has a narrow host-range and can lyse 5 out of 22 K. pneumoniae isolates (22.72%) based on spot test and efficiency of plating (EOP). The zebrafish larvae model was used to test the efficacy of UPM2146 in lysing its host. Based on colony forming unit counts, UPM2146 was able to completely lyse its host at 10 hours onwards. Moreover, we show that the phage is safe to be used in the treatment against K. pneumoniae infections in the zebrafish model.

Matched MeSH terms: Bacteriophages/physiology*
Evaluation of a lytic bacteriophage, Φ st1, for biocontrol of Salmonella enterica serovar Typhimurium in chickens

Wong CL, Sieo CC, Tan WS, Abdullah N, Hair-Bejo M, Abu J, et al.

Int J Food Microbiol, 2014 Feb 17;172:92-101.
PMID: 24361838 DOI: 10.1016/j.ijfoodmicro.2013.11.034

In this study, a Salmonella Typhimurium lytic bacteriophage, Φ st1, which was isolated from chicken faecal material, was evaluated as a candidate for biocontrol of Salmonella in chickens. The morphology of Φ st1 showed strong resemblance to members of the Siphoviridae family. Φ st1 was observed to be a DNA phage with an estimated genome size of 121 kbp. It was found to be able to infect S. Typhimurium and S. Hadar, with a stronger lytic activity against the former. Subsequent characterisation of Φ st1 against S. Typhimurium showed that Φ st1 has a latent period of 40 min with an average burst size of 22 particles per infective centre. Approximately 86.1% of the phage adsorbed to the host cells within the initial 5 min of infection. At the optimum multiplicity of infection (MOI) (0.1), the highest reduction rate of S. Typhimurium (6.6 log₁₀ CFU/ml) and increment in phage titre (3.8 log₁₀ PFU/ml) was observed. Φ st1 produced adsorption rates of 88.4-92.2% at pH7-9 and demonstrated the highest bacteria reduction (6.6 log₁₀ CFU/ml) at pH9. Φ st1 also showed an insignificant different (P>0.05) reduction rate of host cells at 37 °C (6.4 log₁₀ CFU/ml) and 42 °C (6.0 log₁₀ CFU/ml). The in vivo study using Φ st1 showed that intracloacal inoculation of ~10¹² PFU/ml of the phage in the chickens challenged with ~10¹⁰ CFU/ml of S. Typhimurium was able to reduce (P<0.05) the S. Typhimurium more rapidly than the untreated group. The Salmonella count reduced to 2.9 log₁₀ CFU/ml within 6h of post-challenge and S. Typhimurium was not detected at and after 24h of post-challenge. Reduction of Salmonella count in visceral organs was also observed at 6h post-challenge. Approximately 1.6 log₁₀ FU/ml Φ st1 was found to persist in the caecal wall of the chicks at 72 h of post-challenge. The present study indicated that Φ st1 may serve as a potential biocontrol agent to reduce the Salmonella count in caecal content of chickens.

Matched MeSH terms: Bacteriophages/physiology*
Fulltext Anti-biofilm agents: recent breakthrough against multi-drug resistant Staphylococcus aureus

Chung PY, Toh YS

Pathog Dis, 2014 Apr;70(3):231-9.
PMID: 24453168 DOI: 10.1111/2049-632X.12141

Staphylococcus aureus is a Gram-positive pathogen that causes potentially life-threatening nosocomial- and community-acquired infections, such as osteomyelitis and endocarditis. Staphylococcus aureus has the ability to form multicellular, surface-adherent communities called biofilms, which enables it to survive in various sources of stress, including antibiotics, nutrient limitations, heat shock, and immune responses. Biofilm-forming capacity is now recognized as an important virulence determinant in the development of staphylococcal device-related infections. In light of the projected increase in the numbers of elderly patients who will require semi-permanent indwelling medical devices such as artificial knees and hips, we can anticipate an expanded need for new agents and treatment options to manage biofilm-associated infections in an expanding at-risk population. With better understanding of staphylococcal biofilm formation and growth, novel strategies that target biofilm-associated infections caused by S. aureus have recently been described and seem promising as future anti-biofilm therapies.

Matched MeSH terms: Bacteriophages/physiology