Search

Abstract An alkaline active L-glutaminase (BALG) producing bacterium was screened and identified from seamount sediment samples of the Arabian Sea. The isolate was confirmed to be Bacillus australimaris NIOT30 based on morphological characteristics and 16 S rRNA gene sequencing. The glutaminase gene, balg was PCR amplified, cloned and expressed in E. coli BL21 (DE3) host. The molecular weight of purified BALG was estimated to be 36 kDa and the enzyme showed a specific activity of 507 ± 27 Umg−1 against L-glutamine under optimal assay conditions of pH 7.0 and temperature at 37 °C for 15 min. The enzyme showed maximum activity at pH 7 and retained 95% activity at pH 10. BALG retained a relative activity of about 82% and 45% at 45 °C and 60 °C respectively. The kinetic parameters of BALG, Km and Kcat/Km were determined to be of 210 ± 11 mM and 4.4 × 102 M s−1 respectively. Homology modeling and substrate ligand interaction studies revealed the stability of the enzyme-substrate complex. The present study highlights the characterization of a highly active L-glutaminase from B. australimaris NIOT30. Further, mutational analyses of ligand binding residues would show insights into the affinity of L-Glutaminase.

Microplastic pollution has emerged as a significant environmental challenge globally, posing threats to biodiversity, marine life, and human health. Studies indicate that marine organisms, from plankton to larger fish species, and ultimately humans are ingesting microplastics, leading to physiological harm such as inflammation, digestive blockages, tissue injury, hormonal imbalance, reproductive failure and biomagnification through the food chain. Therefore, there arises an urgent need and demand for implementing effective and sustainable remediation solutions. Though, various mitigation technologies are developed, less information is available on the advantages and disadvantages of the technological advancements. The present review highlights the significant information available on the sources, types, transport of microplastics along with the analytical methods to detect the microplastic pollutions. The global perspective of microplastic pollutions with respect to Indian Marine scenario was highlighted. The recent and advanced mitigation technologies and solutions in preventing, reducing and recycling these microplastic pollutions were also addressed. This review further underscores the need for comprehensive strategies to monitor, manage and mitigate microplastic pollution, including policy interventions, public awareness campaigns, and sustainable waste management practices. Addressing this issue is essential for preserving the health of India’s marine ecosystems and safeguarding the livelihoods of mankind.

Abstract Spatio-temporal variation in phytoplankton community dynamics in a temporarily open/closed Swarnamukhi river estuary (SRE), located on the South East coast of India was investigated and correlated to that of the adjacent coastal waters. Understanding the seasonal variability of the phytoplankton community and influencing factors are essential to predicting their impact on fisheries as the river and coastal region serve as the main source of income for the local fishing communities. Downstream before the river meets the sea, an arm of the Buckingham Canal (BC), carrying anthropogenic inputs empties into the Swarnamukhi River (SR1). The impact of anthropogenic effects on the phytoplankton community at BC was compared to other estuarine stations SR2 (upstream), SR1 (downstream), SRM (river mouth) and coastal station (CS). In BC station, harmful algal blooms (HABs) of Chaetoceros decipiens (2940 × 103 cells L−1) and Oscillatoria sp. (1619 × 103 cells L−1) were found during the southwest monsoon and winter monsoon, respectively. These HABs can be linked to the anthropogenic input of increased nutrients and trace metals. The HABs of Oscillatoria sp. were shown to be induced by elevated concentrations of nitrate (10.18 µM) and Ni (3.0 ppm) compared to ambient, while the HABs of C. decipiens were caused by elevated concentrations of silicate (50.35 µM), nitrite (2.1 µM), and phosphate (4.37 µM). Elevated nutrients and metal concentration from the aquaculture farms, and other anthropogenic inputs could be one of the prime reasons for the recorded bloom events at BC station. During this period, observed bloom species density was found low at other estuarine stations and absent at CS. The formation of bloom events during the closure of the river mouth could be a major threat to the coastal ecosystem when it opens. During the Osillatoria sp. bloom, both the Cu and Ni levels were higher at BC. The elevated concentration of nutrients and metals could potentially affect the coastal ecosystem and in turn fisheries sector in the tropical coastal ecosystem.

Mitochondrial genome sequences provide excellent insight into the study of molecular phylogeny and evolution. Mobula tarapacana (Sicklefin devil ray) has an olive-green to brown colored dorsal surface and darkly colored ventral markings. Due to their grey ventral stripes, fisherman and divers sometimes mistake these species for manta rays. To avoid the misidentification during bycatch and to increase the scientific knowledge of this resource as per the SDG Target 14.A, the complete mitogenome sequence of Sicklefin devil ray was sequenced, annotated, and submitted to the GenBank (Accession: MH669414.1). The mitogenome of M. tarapacana is a closed circular dsDNA of 5, 686 bp in size, which transcribes into 13 protein-coding genes (PCGs), 22 tRNAs, and 2 rRNAs. The percentage of protein-coding genes in the genome was 60.30%. Each protein-coding gene is initiated with an ATG codon excluding COX1 and ATP8 that begin with GTG and CCT respectively. Leu (L) and ser (S) were the most common abundant amino acids in the PCGs. The phylogenetic relationship and evolutionary distances were constructed by maximum likelihood approach using MEGA X software. The reported mitogenome was closely related to Mobula kuhlii (MKU MG10, KM364987) and Mobula eregoodootenkee (NC 025954).

Dunaliella salina has been widely reported in the halophilic environment. The present study first time reveals and reports the presence of green alga D. salina identified by both morphological and molecular identification from Andaman and Nicobar Islands, a rainy tropical environment. Besides, it was adapted for the optimization of total carotenoid production by using Taguchi tool with various combinations of different parameters, like light intensity, pH, salinity, NaNO3 and NaH2PO4 in basal De Walne’s medium of which 40µEm-2s-1 light intensity showed maximum production of 249.24 µg/mL of total carotenoid followed by NaNO3, NaH2PO4, pH, and salinity. Hence, this study proves that D. salina possesses the character of adapting to the extreme habitats with total carotenoid production.

Synthetic dyes, extensively used in various industries, act as pollutants in the aquatic environment, and pose a significant threat to living beings. In the present study, we assessed the potential of a halophilic bacterium Salinivibrio kushneri HTSP isolated from a saltpan for decolorization and bioremediation of synthetic dyes. The genomic assessment of this strain revealed the presence of genes encoding the enzymes involved in decolorization mechanisms including FMN-dependent NADH azoreductase Clade III, which cleave the azo bond of the dye, and the enzymes involved in deamination and isomerization of intermediate compounds. The dye decolorization assay was performed using this bacterial strain on three water-soluble dyes in different concentrations: Coomassie brilliant blue (CBB) G-250 (500–3,000 mg/L), Safranin, and Congo red (50–800 mg/L). Within 48 h, more than 80% of decolorization was observed in all tested concentrations of CBB G-250 and Congo red dyes. The rate of decolorization was the highest for Congo red followed by CBB G-250 and then Safranin. Using UV-Visible spectrometer and Fourier Transform Infrared (FTIR) analysis, peaks were observed in the colored and decolorized solutions. The results indicated a breakdown of dyes upon decolorization, as some peaks were shifted and lost for different vibrations of aromatic rings, aliphatic groups (–CH2, –CH3) and functional groups (–NH, –SO3H, and –SO3−) in decolorized solutions. This study has shown the potential of S. kushneri HTSP to decolorize dyes in higher concentrations at a faster pace than previously reported bacterial strains. Thus, we propose that our isolated strain can be utilized as a potential dye decolorizer and biodegradative for wastewater treatment.