Insights into the methodological perspectives for screening polyunsaturated fatty acids-containing bacteria.

Polyunsaturated fatty acids (PUFA) are vital molecules in the pharmaceutical, medical, and nutritional industries. Exploration of bacterial strains capable of producing significant amounts of PUFAs offers a promising avenue for biotechnological applications and industrial-scale production. However, an extensive screening of several samples from diverse sources is highly needed to identify a potential strain. The present study provides the results of the evaluation of 15 different screening methodologies (including changes in existing protocols in terms of reagent concentration, incubation temperature and time) for identifying PUFA-producing bacteria in comparison to the gold standard method (Gas chromatography-mass spectrometry), for the first time. The results determined the most effective techniques for each critical PUFA, leading to an optimized screening process that saves time and resources. The H2O2 plate assay using 0.5% or 1% H2O2 for 72 & 96 h of incubation at 15 °C consistently outperformed others for finding bacteria containing total nutritionally important long chain-PUFA (LC-PUFA), linoleic acid, and arachidonic acid. Whereas the 2,3,5-triphenyl tetrazolium chloride broth assay at 10-15 °C was the most effective and semiquantitative screening methodology for eicosapentaenoic acid (EPA) and alpha-linolenic acid-containing bacteria. Apart from the methodological perspectives, the study also revealed certain potential strains to be targeted in the ongoing research on PUFA-containing bacteria. Further, the manuscript forms the first report on the presence of docosahexaenoic acid (DHA) in Shewanella decolorationis, EPA in Psychrobacter maritimus and Micrococcus aloeverae, and both EPA and DHA in Arthrobacter rhombi. Altogether, the paper generates several thought-provoking insights on the methodological perspectives and identifies potential PUFA-containing bacteria with practical applications in future bacteria-based PUFA research.

A Global-Scale Ecological Niche Modeling of the Emerging Pathogen Serratia marcescens to Aid in its Spatial Ecology.

Serratia marcescens is a big emerging concern for human health and coral biodiversity. Spatial ecology and the influencing factors on pathogen ecology, however, remain unknown. The study forms the first global risk assessment of S. marcescens. MaxEnt niche modeling was applied using two biotic and sixteen abiotic variables. The world was classified into five risk-level categories based on the pathogen ecology, and the world population exposed to S. marcescens infection was then quantified. The prepared model showed an area under the curve value of 0.918 ± 0.028, implying excellent prediction ability. The highly and moderately suitable areas occupied around 0.52% and 17.9% of the total global land area. The order of probability of having S. marcescens-related infections was Asia > North America > South America > Europe > Africa > Australia. Human population density and temperature were the most influential factors in the distribution. The moderate to high transmission risk zones contained 0.20% (1.61 billion people) of the human population. In brief, these results give novel insights into its spatial ecology and provide the risk maps that can be utilized to plan targeted strategic control measures against future invasions of this emerging pathogen.

Spatio-temporal variability of physico-chemical variables, chlorophyll a, and primary productivity in the northern Arabian Sea along India coast.

The present study attempts to understand the seasonal and spatial variations in the physico-chemical (temperature, pH, salinity, dissolved oxygen, and nutrients) and productivity characteristics of the northern Arabian Sea off the Indian coast. Samples were collected from four different sites off the Veraval coast. The values of the physical and chemical variables were higher during the summer season, whereas nutrient concentrations were high during the winter season due to the maturity of intake nutrients during post-monsoon and winter convective mixing during the northeast monsoon. The dissolved oxygen (DO) concentration was strongly and positively correlated with the net primary productivity (NPP) and chlorophyll a (Chl-a) content to support productivity along the region. Dissimilarity in study variables was observed between the inshore and offshore locations. Principal component analysis revealed a strong relationship between nutrients and productivity variables (Chl-a and NPP). Nutrient levels were high at inshore sites, which can be attributed to the heavy nutrient load from land-based anthropogenic activities and impact due to natural processes like water mixing, sedimentation, and wave activities. Nutrients were strongly and positively correlated with the productivity variables, i.e., Chl-a and NPP. Chl-a positively correlated with NPP (r = 0.90), which indicates that it is a principle productivity pigment in the marine ecosystem.