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.

Degradation of marine crustacean shell wastes through single-stage co-fermentation using proteolytic and chitinolytic bacteria.

Management of crustacean shell waste (SW) through an eco-friendly technique is an environmental obligation to control pollution. The present study showed a novel approach through the simultaneous application of proteolytic and chitinolytic bacteria to effectively degrade unprocessed crustacean SW. For this, the bacteria with concurrent chitinolytic and proteolytic activity (Bacillus subtilis, Priestia megaterium, or Bacillus amyloliquefaciens) were applied either alone or in combination with one proteolytic strain (Paenibacillus alvei) in the unprocessed lobster, crab, and shrimp SW. The method degraded the shells with high deproteinization (> 90%) and demineralization efficiency (> 90%). The degradation was confirmed through scanning electron microscopy. The highest weight loss achieved with shrimp, crab, and lobster shells was 93.67%, 82.60%, and 83.33%, respectively. B. amyloliquefaciens + P. alvei combination produced the highest weight loss in crab and lobster SW, whereas all combinations produced statistically similar weight loss in shrimp SW. There was a concurrent production of N-acetyl glucosamine (up to 532.89, 627.87, and 498.95 mg/g of shrimp, lobster, and crab shell, respectively, with P. megaterium + P. alvei and B. amyloliquefaciens + P. alvei in all SW) and amino acids (4553.8, 648.89, 957.27 µg/g of shrimp, lobster, and crab shells, respectively with B. subtilis + P. alvei in shrimp and B. amyloliquefaciens + P. alvei in crab and lobster). Therefore, it is concluded that, for the first time, efficient degradation of crustacean shell waste was observed using chitinolytic and proteolytic bacterial fermentation with the obtention of byproducts, providing a basis for further application in SW management.