Thraustochytrids of Mangrove Habitats from Andaman Islands: Species Diversity, PUFA Profiles and Biotechnological Potential.

Thraustochytrids are the most promising microbial source for the commercial production of docosahexaenoic acid (DHA) for its application in the human health, aquaculture, and nutraceutical sectors. The present study isolated 127 thraustochytrid strains from mangrove habitats of the south Andaman Islands, India to study their diversity, polyunsaturated fatty acids (PUFAs), and biotechnological potential. The predominant strains were identified as belonging to two major genera (Thraustochytrium, Aurantiochytrium) based on morphological and molecular characteristics. The strain ANVKK-06 produced the maximum biomass of 5.42 g·L-1, while ANVKK-03 exhibited the maximum total lipid (71.03%). Omega-3 PUFAs such as eicosapentaenoic acid (EPA) accumulated up to 11.03% in ANVKK-04, docosapentaenoic acid (DPA) up to 8.65% in ANVKK-07, and DHA up to 47.19% in ANVKK-06. ANVKK-06 showed the maximum scavenging activity (84.79 ± 2.30%) while ANVKK-03 and ANVKK-10 displayed the highest antibacterial activity against human and fish pathogens, S. aureus (18.69 ± 1.2 mm) and V. parahaemolyticus (18.31 ± 1.0 mm), respectively. All strains were non-toxic as evident by negative blood agar hemolysis, thus, the thraustochytrids are suggested to be a potential source of DHA for application in the health care of human and fish.

Draft genome sequence of marine sediment-derived red pigmented bacteria Zooshikella sp. strain S2.1 with potential biomedical applications.

The present study is aimed to determine the draft genome of novel species of Zooshikella strain S2.1, a potential red pigmented strain isolated recently from the coastal sediment of Andaman and Nicobar Islands, India. This Gram negative, rod shaped aerobic bacterium produces pink, yellowish-red and dark red with metallic green sheen pigmentation on agar plates. It is able to grow under NaCl concentrations of 1 to 9%. This species has antimicrobial, antioxidant, dye and food colorant applications. Whole genome sequence analysis revealed that strain S2.1 represents a novel species of the genus Zooshikella. Draft genome and 16 s rRNA sequences of this species were deposited in GenBank under the Sequence Read Archive accession number PRJNA514840 and GenBank number MK680108, respectively. Here we report the draft genome of Zooshikella sp. strain S2.1 with ~5.9 Mb of chromosomal content and ~0.34 Mb of extra-chromosomal content.

Existence in cellulose shelters: industrial and pharmaceutical leads of symbiotic actinobacteria from ascidian Phallusia nigra, Andaman Islands.

The diversity of actinobacteria associated with marine ascidian Phallusia nigra from Andaman Islands was investigated. A total of 10 actinobacteria were isolated and based on the biochemical and molecular characterization, the isolates were assigned to 7 different actinobacterial genera. Eight putatively novel species belonging to genera Rhodococcus, Kineococcus, Kocuria, Janibacter, Salinispora and Arthrobacter were identified based on 16S rDNA sequence similarity with the NCBI database. The organic extracts of ten isolates displayed considerable bioactivity against test pathogens, which were Gram-positive and Gram-negative in nature. PCR-based screening for type I and type II polyketide synthases (PKS-I, PKS-II) and nonribosomal peptide synthetases (NRPS) revealed that, 10 actinobacterial isolates encoded at least one type of polyketide synthases biosynthesis gene. Majority of the isolates found to produce industrially important enzymes; amylase, protease, gelatinase, lipase, DNase, cellulase, urease, phosphatase and L-asparaginase. The present study emphasized that, ascidians are a prolific resource for novel bioactive actinobacteria with potential for novel drug discovery. This result expands the scope to functionally characterize the novel ascidian associated marine actinobacteria and their metabolites could be a source for the novel molecules of commercial interest.

Biodiversity and antibacterial potential of cultivable halophilic actinobacteria from the deep sea sediments of active volcanic Barren Island.

Deep Sea sediment cores were collected from the surrounding of active volcanic Barren Island, Andaman & Nicobar Islands. A total of 123 cultivable marine actinobacteria were isolated and identified based on their biochemical and 16S rDNA sequences. The isolates were categorized under 10 genera, of which Streptomyces sp., Dietzia sp. and Brevibacterium sp. are the dominant genera. Of 123 isolates, 73 isolates exhibited appreciable inhibitory activity against both Gram positive and Gram negative bacteria. High frequencies of positive PCR amplification were obtained for PKS-I (39.13%), PKS-II (56.52%) and NRPS (69.57%). The highest levels of biosynthetic systems were observed for NRPS and PKS-II. Majority of the actinobacterial isolates revealed excellent potential for bioprospecting of novel byproducts with industrial and pharmaceutical importance.

Ectoine biosynthesis genes from the deep sea halophilic eubacteria, Bacillus clausii NIOT-DSB04: Its molecular and biochemical characterization.

Ectoine, the most prominent osmolyte in nature, is a vital compatible solute present in halophilic bacterium. It protects the cellular biomolecules of the halophilic bacteria and retains their intrinsic function from extreme circumstances. In the current research, ectoine biosynthesis gene cluster (ectABC) in Bacillus clausii NIOT-DSB04 was expressed heterologically in E. coli M15 (pREP4). RP-HPLC resolved several fractions of the purified recombinant product, one of which had been confirmed as ectoine. The recombinant ectoine was further characterized by 1H and 13C Nuclear Magnetic Resonance. The purified recombinant ectoine was also authenticated by FT-IR studies with the existence of ester carbonyl and C-H group. In IPTG induced E. coli M15 transgenic cells, the enzymatic activity of the ectA, B and C genes were found to be higher than that of uninduced cells.

Novel glutaminase free L-asparaginase from Nocardiopsis alba NIOT-VKMA08: production, optimization, functional and molecular characterization.

Studies were carried out for the optimization and production of novel extracellular glutaminase-free L-asparaginase from Nocardiopsis alba NIOT-VKMA08. Among the tested carbon and nitrogen sources, maximum L-asparaginase production was observed with a combination of L-asparagine and maltose (1.5%) and twofold increase in yield (18.47 IU mL(-1)) was observed with newly optimized NIOT-asparaginase medium. Activity of the purified enzyme was moderately inhibited by various divalent cations and thiol group blocking reagents, with K(m) and V(max) of 0.127 mM and 5.50 U µg(-1). Optimum pH and temperature of purified L-asparaginase for the hydrolysis of L-asparagine was 8.0 and 37 °C, respectively. The enzyme inhibited polyacrylamide formation in 10% solution and it was very specific for its natural substrate L-asparagine. Partial glutaminase activity was not detected, which could reduce the possibility of side effects during cancer therapy. L-Asparaginase biosynthesis gene (ansA) was cloned and transformed in E. coli JM109. The ansA gene sequence reported in this study contains several base substitutions with that of reported sequences in GenBank, resulting in altered amino acid sequences of the translated protein.

Heterologous expression, purification, and phylogenetic analysis of oil-degrading biosurfactant biosynthesis genes from the marine sponge-associated Bacillus licheniformis NIOT-06.

Surfactin is a lipopeptide, composed of one ß-hydroxy fatty acid, a long fatty acid moiety, and seven amino acids. In this study, the biosurfactant biosynthesis genes; 4'-pantetheinyl transferase (sfp), phosphopantetheinyl transferase (sfpO), and surfactin synthetase (srfA) have been characterized from the marine sponge-associated Bacillus licheniformis NIOT-06 from the Andaman and Nicobar Islands. The purified recombinant biosurfactant revealed excellent emulsification activity with crude oil and kerosene. Reverse-phase high-performance liquid chromatography resolved the purified recombinant biosurfactant into several fractions and one of which had significant surface tension reducing property. Fourier transform infrared spectroscopy spectrum also revealed the presence of C-N-N, alkenes, and N-H as the functional groups, and a similar overlapping pattern was observed with that of standard lipopeptide surfactin. The diversity and phylogeny of sfp, sfpO, and srfA gene sequences were compared with other eubacteria. The sfp, sfpO, and srfA gene sequences obtained from Bacillus licheniformis NIOT-06 were diverse and appeared to be partially conserved when compared with the GenBank reported sequences of several eubacteria.

Extensive Chaetoceros curvisetus bloom in relation to water quality in Port Blair Bay, Andaman Islands.

Blooming of diatom species Chaetoceros curvisetus (Cleve, 1889) was observed in Junglighat Bay and Haddo Harbour of Port Blair Bay of Andaman and Nicobar Islands during June 2010. Physico-chemical parameters, nutrient concentrations and phytoplankton composition data collected from five stations during 2010 were classified as bloom area (BA) and non-bloom area (NBA) and compared. Elevated values of dissolved oxygen were recorded in the BA, and it significantly varied (p < 0.01) from NBA. Among the nutrient parameters studied, nitrate concentration indicated significant variation in BA and NBA (p < 0.01). Phosphate and ammonia concentrations reduced to below detection level (BDL) in the BA and NBA, indicating its utilization. In Junglighat Bay, the C. curvisetus species constituted 93.4 and 69.2% composition of total phytoplankton population during day 1 and day 2, respectively. The bloom forming stations separated out from the non-bloom forming station in non-parametric multidimensional scaling (nMDS) ordinations; cluster analysis powered by SIMPROF test also grouped the stations as BA and NBA.

Novel marine actinobacteria from emerald Andaman & Nicobar Islands: a prospective source for industrial and pharmaceutical byproducts.

BACKGROUND: Andaman and Nicobar Islands situated in the eastern part of Bay of Bengal are one of the distinguished biodiversity hotspot. Even though number of studies carried out on the marine flora and fauna, the studies on actinobacteria from Andaman and Nicobar Islands are meager. The aim of the present study was to screen the actinobacteria for their characterization and identify the potential sources for industrial and pharmaceutical byproducts. RESULTS: A total of 26 actinobacterial strains were isolated from the marine sediments collected from various sites of Port Blair Bay where no collection has been characterized previously. Isolates were categorized under the genera: Saccharopolyspora, Streptomyces, Nocardiopsis, Streptoverticillium, Microtetraspora, Actinopolyspora, Actinokineospora and Dactylosporangium. Majority of the isolates were found to produce industrially important enzymes such as amylase, protease, gelatinase, lipase, DNase, cellulase, urease and phosphatase, and also exhibited substantial antibacterial activity against human pathogens. 77% of isolates exhibited significant hemolytic activity. Among 26 isolates, three strains (NIOT-VKKMA02, NIOT-VKKMA22 and NIOT-VKKMA26) were found to generate appreciable extent of surfactant, amylase, cellulase and protease enzyme. NIOT-VKKMA02 produced surfactant using kerosene as carbon source and emulsified upto E(24)-63.6%. Moreover, NIOT-VKKMA02, NIOT-VKKMA22 and NIOT-VKKMA26 synthesized 13.27 U/ml, 9.85 U/ml and 8.03 U/ml amylase; 7.75 U/ml, 5.01 U/ml and 2.08 U/ml of cellulase and 11.34 U/ml, 6.89 U/ml and 3.51 U/ml of protease enzyme, respectively. CONCLUSIONS: High diversity of marine actinobacteria was isolated and characterized in this work including undescribed species and species not previously reported from emerald Andaman and Nicobar Islands, including Streptomyces griseus, Streptomyces venezuelae and Saccharopolyspora salina. The enhanced salt, pH and temperature tolerance of the actinobacterial isolates along with their capacity to secrete commercially valuable primary and secondary metabolites emerges as an attractive feature of these organisms. These results are reported for the first time from these emerald Islands and expand the scope to functionally characterize novel marine actinobacteria and their metabolites for the potential novel molecules of commercial interest.

Microplastic intrusion into the zooplankton, the base of the marine food chain: Evidence from the Arabian Sea, Indian Ocean.

Microplastics (MPs) are ubiquitous in the marine environment, yet information regarding their occurrence in the food web is limited. We investigated the concentration and composition of MPs in water and diverse zooplankton groups from the Arabian Sea basin. Forty-one zooplankton tows were collected with a bongo net (330 µm mesh) from the Arabian Sea in January 2019. MPs in the surface water varied between 0 and 0.055 particles/m3, with a relatively higher concentration (0.013 ± 0.002 particles/m3) in the central Arabian Sea. Though fibrous MPs were most abundant in the seawater (77.14 %), zooplankton prefers small fragments (55.3 %). The size of MPs was distinctly smaller (277.1 ± 46.74 µm) in zooplankton than that in seawater (864.32 ± 73.72 µm), and MPs bioaccumulation was observed in almost all the zooplankton functional groups. Polymer composition revealed polyamide, polyethylene, polypropylene, and PVC were abundant in water and zooplankton, suggesting that the textile, fishing, shipping, and packaging industries are significant sources. The prevailing northeasterly winds, strong West India Coastal Current, and conducive westward radiated Rossby wave during January 2019 have carried the microplastic contaminated water mass away from the coast, posing a threat to the open ocean ecosystems. These results demand further attention to investigate the state of plastic pollution in the Arabian Sea basin.

Unraveling the plastic degradation potentials of the plastisphere-associated marine bacterial consortium as a key player for the low-density polyethylene degradation.

The omnipresent accumulation and non-degradable nature of plastics in the environment are posing an ever-increasing ecological threat. In this study, a total of 97 bacteria were isolated from macroplastic debris collected from the coastal environments of Andaman Island. The isolates were screened for LDPE degradation potential and were identified based on phenotypic, biochemical, and molecular characterization. 16S rDNA-based identification revealed that three-three isolates of each belong to the genus Oceanimonas and Vibrio, two were closely related to the genus Paenibacillus whereas, one-one was associated with the genus Shewanella, Rheinheimera, and Bacillus, respectively. A bacterial consortium was formulated using the top four isolates based on their individual LDPE degradation potentials. A significant increase (p < 0.05) in the mean LDPE degradation (47.07 ± 6.67% weight-loss) and change in thickness was observed after 120 days of incubation. FTIR spectrum, 13C NMR, and TG-DSC analyses demonstrated changes in the LDPE sheets' functional groups, crystallinity, and in thermal properties after 120 days of incubation. The SEM and AFM images confirmed bacterial attachments, an increase in surface roughness and deformities on LDPE sheets. This study reports a bacterial consortium that can efficiently degrade the plastics and can be used in providing eco-friendly mitigation of plastic waste.

Microplastics particles in seafloor sediments along the Arabian Sea and the Andaman Sea continental shelves: First insight on the occurrence, identification, and characterization.

Microplastics (MPs) are widely-recognized contaminants and marine sediments act as a sink of MPs and therefore may cause a potential threat to benthic communities. We aim to analyze the MPs abundances and characteristics in the seafloor sediments from the continental shelves of the Arabian and Andaman seas. Twenty-two seafloor sediments were collected from 8 and 14 locations of the Arabian and Andaman seas, respectively. MPs concentrations varied from not detected (ND) to 267 particles kg-1 with mean values of 128.02 ± 33.92 and 15.36 ± 2.61 particles kg-1, respectively for the Arabian and Andaman seas. Among different shapes, fiber had the highest distribution over fragments and pellet. FT-IR analysis revealed acrylic was most dominant polymer, followed by polyethylene, and nylon. Mean MP concentration at the Arabian Sea was significantly higher (p < 0.001) than in the Andaman Sea. The present study revealed the wide-spread occurrence of MPs throughout the Indian seas.

Complete Genome Analysis of Undecylprodigiosin Pigment Biosynthesizing Marine Streptomyces Species Displaying Potential Bioactive Applications.

Marine Streptomyces species are underexplored for their pigment molecules and genes. In this study, we report the genome of the undecylprodigiosin biosynthesizing gene cluster carrying Streptomyces sp. strain BSE6.1, displaying antioxidant, antimicrobial, and staining properties. This Gram-positive obligate aerobic bacterium was isolated from the coastal sediment of the Andaman and Nicobar Islands, India. Pink to reddish pigmented colonies with whitish powdery spores on both agar and broth media are the important morphological characteristics of this bacterium. Growth tolerance to NaCl concentrations was 2 to 7%. The assembled genome of Streptomyces sp. BSE6.1 contains one linear chromosome 8.02 Mb in length with 7157 protein-coding genes, 82 tRNAs, 3 rRNAs and at least 11 gene clusters related to the synthesis of various secondary metabolites, including undecylprodigiosin. This strain carries type I, type II, and type III polyketide synthases (PKS) genes. Type I PKS gene cluster is involved in the biosynthesis of red pigment undecylprodigiosin of BSE6.1, similar to the one found in the S. coelicolor A3(2). This red pigment was reported to have various applications in the food and pharmaceutical industries. The genome of Streptomyces sp. BSE6.1 was submitted to NCBI with a BioProject ID of PRJNA514840 (Sequence Read Archive ID: SRR10849367 and Genome accession ID: CP085300).

Molecular characterization, phylogenetic and in silico sequence analysis data of trehalose biosynthesis genes; otsA and otsB from the deep sea halophilic actinobacteria, Streptomyces qinglanensis NIOT-DSA03.

Trehalose, a non-reducing disaccharide (α-D-glucopyranosyl-(1→1)-α-D-glucopyranoside) is a natural compound, which serves as a protective substance in halophilic bacterial cells. Trehalose biosynthesis genes (otsA and otsB) were PCR amplified from the genomic DNA of deep sea actinobacteria, Streptomyces qinglanensis NIOT-DSA03. The amplified genes were cloned and nucleotide sequences were determined. In silico sequence and phylogenetic analysis of nucleotides and amino acids of otsA and otsB sequences of S. qinglanensis were also determined. The experimental data described in this study will be helpful to develop a recombinant expression system to produce trehalose for biotechnological applications.

Taxonomic Composition and Biological Activity of Bacterial Communities Associated with Marine Ascidians from Andaman Islands, India.

Marine invertebrates, particularly ascidians, constitute an important source of potential active and biofunctional natural products. The microbial diversity associated with ascidians is little recognized, although these microorganisms play a vital role in marine ecosystems. The objective of this study was to investigate bacterial population diversity in four ascidian samples: Phallusia nigra, Phallusia fumigata, Eudistoma viride, and Rhopalaea macrothorax, collected from the North Bay, Andaman and Nicobar Islands. Microbial strains identified up to the species level revealed 236 distinct species/ribotypes out of 298 bacterial strains. Of 298 ascidian-associated bacteria, 72 isolates belong to the class Gammaproteobacteria and the genus Endozoicomonas. The results from this investigation will contribute a broaden knowledge of microbial diversity associated to marine ascidians, and as a promising source for the discovery of new natural products.

Deep-sea mercury resistant bacteria from the Central Indian Ocean: A potential candidate for mercury bioremediation.

Deep-sea bacteria when grown in normal environmental conditions get morphologically and genetically adapted to resist the provided culture conditions for their survival, making them a possible aspirant in mercury bioremediation. In this study, seawater samples were collected from different depths of the Central Indian Ocean and seven mercury resistant bacteria (resistant to 100 mg L-1 concentration of inorganic Hg as HgCl2) were isolated. Based on 16S rRNA gene sequencing, the identified isolates belong to the genera Pseudomonas, Bacillus and Pseudoalteromonas. The presence of the merA gene in the isolates contributes to the effective volatilization of mercury. The Inductively Coupled Plasma Mass-Spectroscopy analysis revealed that the isolates can reduce up to >80% of inorganic mercury. Moreover, Fourier Transform Infrared spectrum analysis indicates that functional groups play a key role in the mechanism of adaptation towards Hg2+ reduction. Thus, the deep-sea bacteria expressed significant tolerance and reduction potential towards ionic mercury.

First evidence of microplastics bioaccumulation by marine organisms in the Port Blair Bay, Andaman Islands.

Microplastic (MP) pollution has become a global concern. We aim to quantify the extent of MP pollution in the coastal ecosystem of the Port Blair Bay, A&N Islands. Water, sediment, zooplankton, finfish, and shellfish samples were collected from the Port Blair Bay and analyzed for the presence of MP. Average concentrations of MP in water, sediment, zooplankton, finfish, and shellfishes were found to be 0.93 ± 0.59 particles per m3, 45.17 ± 25.23 particles per kilogram, 0.12 ± 0.07 pieces per zooplankter and 10.65 ± 7.83 particles per specimen, respectively. High amount of MP retention was observed in the zooplankton community. Maximum MP ingestion was observed in adult Carangoides malabaricus. Fiber was most abundant in water, sediment, and fish samples, followed by fragment and pellet. However, fragments were predominant in zooplankton. Nylon, acrylic, and ionomer surlyn were most abundant polymer types in the bay environment. These results demand further attention to combat plastic pollution in the coastal ecosystem.

A novel approach to predict chlorophyll-a in coastal-marine ecosystems using multiple linear regression and principal component scores.

Chlorophyll-a is an established indexing marker for phytoplankton abundance and biomass amongst primary food producers in an aquatic ecosystem. Understanding and modeling the level of Chlorophyll-a as a function of environmental parameters have been found to be very beneficial for the management of the coastal ecosystems. This study developed a mathematical model to predict Chlorophyll-a concentrations based on a data driven modeling approach. The prediction model was developed using principal component analysis (PCA) and multiple linear regression analysis (MLR) approaches. The predictive success (R2) of the model was found to be ~84.8% for first approach and ~83.8% for the second approach. A final model was generated using a combined principal component scores (PCS) and MLR approach that involves fewer parameters and has a predictive ability of 83.6%. The PCS-MLR method helped to identify the relationship amongst dependent as well as predictor variables and eliminated collinearity problems. The final model is quite simple and intuitive and can be used to understand real system operations.

Applications of Prodigiosin Extracted from Marine Red Pigmented Bacteria Zooshikella sp. and Actinomycete Streptomyces sp.

This study is aimed to determine the distribution, diversity and bioprospecting aspects of marine pigmented bacteria (MPB) isolated from pristine Andaman Islands, India. A total of 180 samples including seawater, sediment, marine plants, invertebrates, and vertebrates were collected and investigated for isolating pigmented bacteria. Results revealed that sediment, invertebrates, and seawater samples were colonized with a greater number of pigmented bacteria pertains to 27.9 × 103 CFU/mL, 24.1 × 103 CFU/mL and 6.7 × 103 CFU/mL respectively. Orange (21.6 × 103 CFU/mL) and red (8.0 × 103 CFU/mL) MPB were predominant than other pigmented bacteria. Fourteen potential MPB were selected based on their intense pigmentation and tested for bioactive nature and food colorant applications. Out of 14, two red pigmented strains BSE6.1 & S2.1 displayed potential multifaceted applications, such as antibacterial, antioxidant, food colorant, and staining properties. Brown pigmented strains CO8 and yellow pigmented strain SQ2.3 have displayed staining properties. Chemical characterization of red pigment using TLC, HP-LC, GC-MS, FT-IR and 1H-NMR analysis revealed prodigiosin as a main chemical constituent. Pure form of prodigiosin compound fractions obtained from both the strains displayed effective antibacterial activity against different human pathogens. MIC and MBC assays revealed that S2.1 requires 300 µg and 150 µg, respectively, and BSE6.1 require 400 µg concentrations of pigment compound for complete inhibition of S. aureus subsp. aureus. On the basis of 16S rRNA sequence analysis, strains S2.1 and BSE6.1 were identified as Zooshikella sp. and Streptomyces sp. and assigned under the GenBank accession numbers: MK680108 and MK951781 respectively.

A multiplex PCR kit for the detection of three major virulent genes in Enterococcus faecalis.

A multiplex PCR kit that detects three major virulence genes, gelE, hyl and asaI, in Enterococcus faecalis was developed. Analyses of the available sequences of three major virulence genes and designed primers allowed us to develop the three-gene, multiplex PCR protocol that maintained the specificity of each primer pair. The resulting three amplicon bands for gelE, hyl and asaI were even and distinct with product sizes of 213, 273 and 713 bp, respectively. The multiplex PCR procedure was validated with a total of 243 E. faecalis strains that included 02 ATCC strains, 109 isolates from marine samples (sediment, water and sea foods), 22 isolates from cattle fodder, 79 isolates fresh water samples and 31 isolates from nosocomial samples. Specificity of the kit was indicated by amplification of only three major virulent genes gelE, hyl and asaI without any nonspecific bands. Tests for the limit of detection revealed that amplified genes from the sample with a minimum of 104 CFU/g or CFU/mL (10 cells/reaction) of E. faecalis and lower cell load samples, after a 3 h enrichment in NIOT-E. faecalis enrichment medium at 37 °C, a sensitivity level of 10 CFU/g or CFU/mL was achieved.