Bacteriophage DNA glucosylation impairs target DNA binding by type I and II but not by type V CRISPR-Cas effector complexes

Prokaryotes encode various host defense systems that provide protection against mobile genetic elements. Restriction-modification (R-M) and CRISPR-Cas systems mediate host defense by sequence specific targeting of invasive DNA. T-even bacteriophages employ covalent modifications of nucleobases to avoid binding and therefore cleavage of their DNA by restriction endonucleases. Here, we describe that DNA glucosylation of bacteriophage genomes affects interference of some but not all CRISPR-Cas systems. We show that glucosyl modification of 5-hydroxymethylated cytosines in the DNA of bacteriophage T4 interferes with type I-E and type II-A CRISPR-Cas systems by lowering the affinity of the Cascade and Cas9-crRNA complexes for their target DNA. On the contrary, the type V-A nuclease Cas12a (also known as Cpf1) is not impaired in binding and cleavage of glucosylated target DNA, likely due to a more open structural architecture of the protein. Our results suggest that CRISPR-Cas systems have contributed to the selective pressure on phages to develop more generic solutions to escape sequence specific host defense systems

Isolation and cellular fatty acid profile analyzation of two marine bioluminescent bacteria

192-195Two luminescent bacterial strains KOOS1 and KOOS2 isolated from surface mucus of Octopus sp. collected from Andaman were identified by their cellular fatty acid composition analyzation with the help of Microbial Identification system (MIDI). SIM indexes obtained for these isolated strains were 0.772 (KOOS1) and 0.754 (KOOS2) respectively and were identified as Photobacterium damselae and Vibrio fischeri. Major fatty acids found in Photobacterium damselae were Saturated: Dodecanoic acid (C12:0), Tetradecanoic acid (C14:0), Pentadecanoic acid (C15:0), Hexadecanoic acid (C16:0), Heptadecanoic acid (C17:0) and Octadecanoic acid (C18:0); and Unsaturated: 3-hydroxy-9-methyl decanoic acid (C11:0iso 3OH), 3-hydroxydodecanoic(C12:0 3OH), C16:1ω5c, Oleic acid (C18:1ω9c) and C18:1ω5c.In Vibrio fischeri Saturated: C12:0, Tridecanoic acid (C13:0), C15:0, C16:0, C17:0 and C18:0; and Unsaturated: C11:0iso 3OH,2-hydroxydodecanoic (C12:0 2OH), C12:03OH, C13:0iso, C14:0iso, C15:0iso, C15:0anteiso, C16:0iso, C17:0iso, C16:1ω5c, C15:0iso3OH, C17:1 ω8c and C17:1ω6c were found. Cyclopropane acids have not been detected in both Photobacterium damselae and Vibrio fischeri

Pathogen-induced activation of disease-suppressive functions in the endophytic root microbiome

Microorganisms living inside plants can promote plant growth and health, but their genomic and functional diversity remain largely elusive. Here, metagenomics and network inference show that fungal infection of plant roots enriched for Chitinophagaceae and Flavobacteriaceae in the root endosphere and for chitinase genes and various unknown biosynthetic gene clusters encoding the production of nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs). After strain-level genome reconstruction, a consortium of Chitinophaga and Flavobacterium was designed that consistently suppressed fungal root disease. Site-directed mutagenesis then revealed that a previously unidentified NRPS-PKS gene cluster from Flavobacterium was essential for disease suppression by the endophytic consortium. Our results highlight that endophytic root microbiomes harbor a wealth of as yet unknown functional traits that, in concert, can protect the plant inside ou

Pathogen-induced activation of disease-suppressive functions in the endophytic root microbiome

Microorganisms living inside plants can promote plant growth and health, but their genomic and functional diversity remain largely elusive. Here, metagenomics and network inference show that fungal infection of plant roots enriched for Chitinophagaceae and Flavobacteriaceae in the root endosphere and for chitinase genes and various unknown biosynthetic gene clusters encoding the production of nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs). After strain-level genome reconstruction, a consortium of Chitinophaga and Flavobacterium was designed that consistently suppressed fungal root disease. Site-directed mutagenesis then revealed that a previously unidentified NRPS-PKS gene cluster from Flavobacterium was essential for disease suppression by the endophytic consortium. Our results highlight that endophytic root microbiomes harbor a wealth of as yet unknown functional traits that, in concert, can protect the plant inside out.</p

Pathogen-induced activation of disease-suppressive functions in the endophytic root microbiome

Microorganisms living inside plants can promote plant growth and health, but their genomic and functional diversity remain largely elusive. Here, metagenomics and network inference show that fungal infection of plant roots enriched for Chitinophagaceae and Flavobacteriaceae in the root endosphere and for chitinase genes and various unknown biosynthetic gene clusters encoding the production of nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs). After strain-level genome reconstruction, a consortium of Chitinophaga and Flavobacterium was designed that consistently suppressed fungal root disease. Site-directed mutagenesis then revealed that a previously unidentified NRPS-PKS gene cluster from Flavobacterium was essential for disease suppression by the endophytic consortium. Our results highlight that endophytic root microbiomes harbor a wealth of as yet unknown functional traits that, in concert, can protect the plant inside out.Microbial Biotechnolog

Guide-free Cas9 from pathogenic Campylobacter jejuni bacteria causes severe damage to DNA

CRISPR-Cas9 systems are enriched in human pathogenic bacteria and have been linked to cytotoxicity by an unknown mechanism. Here, we show that upon infection of human cells, Campylobacter jejuni secretes its Cas9 (CjeCas9) nuclease into their cytoplasm. Next, a native nuclear localization signal enables CjeCas9 nuclear entry, where it catalyzes metal-dependent nonspecific DNA cleavage leading to cell death. Compared to CjeCas9, native Cas9 of Streptococcus pyogenes (SpyCas9) is more suitable for guide-dependent editing. However, in human cells, native SpyCas9 may still cause some DNA damage, most likely because of its ssDNA cleavage activity. This side effect can be completely prevented by saturation of SpyCas9 with an appropriate guide RNA, which is only partially effective for CjeCas9. We conclude that CjeCas9 plays an active role in attacking human cells rather than in viral defense. Moreover, these unique catalytic features may therefore make CjeCas9 less suitable for genome editing applications

Distribution of bioluminescent polychaete larvae of <i>Odontosyllis</i> sp. in South Andaman

735-737Larval distribution of a luminous Odontosyllis sp. on different marine niches such as the articulated coralline red algae Amphirova anceps, algal mats on boats, seawater and sediment is being reported here for the first time from Burmanallah Coast.The freshly collected luminous larvae of Odontosyllis sp. from these niches emitted an intense glow of luminescence upon the addition of freshwater and upon gentle disturbance. Flashes of internal luminescence was appeared in freshly collected larvae, whereas continuous glow lasted for few minutes when freshwater was added. Luminescent bacteria were not observed in these larvae, indicating that their luminescence emission is not due to bacterial production, but could be the self-internal emission mechanism

Polymorphic mantle tissue patterns of <i>Tridacna</i> of Burmanallah coast, South Andaman

141-146We investigated 42 different mantle tissue patterns in Tridacna species along the coast of Burmanallah, Andamans. Out of 42 mantle tissue patterns, T. maxima showed 18 different mantle patterns, T. crocea showed 22 different mantle patterns and T. squamosa showed only two patterns. T. maxima showed dominance of distribution than T. crocea and T. squamosa. Mostly T. maxima and T. crocea were observed in shallow waters and T. squamosa was present on the slope edge of reefs

Molecular characterization of marine pigmented bacteria showing antibacterial activity

2081-2087In the present study 6 pigmented marine bacterial (PMB) strains BNO10, BNO20, BSO14, BNY11, CSP15 and BNB21 from marine sediment and 2 strains BWR18 and BWCY16 from seawater sample were isolated on Zobell Marine agar. These PMB appeared to be in blue, orange, pink, red, dark brownish yellow and yellowish green in colour. Phylogenetic analysis on the basis of small subunit ribosomal RNA (16s rRNA) gene partial sequence homologies of these isolates were identified as Bacillus flexus (BNY11, BWR18), Micrococcus luteus (BWCY16), Photobacterium ganghwense (CSP15), Stenotrophomonas maltophilia (BNO10, BNO20, BSO14), and Vibrio sp. (BNB21). Large and clear zones of inhibition formed by these bacteria against different human pathogenic bacteria were detailed