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A novel pretreatment process based on prioritized microbes was developed to improve the yield of reducing sugars from red (Gracilaria corticata), brown (Sargassum wightii), and green (Ulva fasciata) seaweeds as a cheap, eco-friendly method for seaweed saccharification. Prioritization of six microbes from a collection of 24 microbes was initially done using a unique stepwise strategy considering different polysaccharides present in varied seaweed types. Final selection of three microbes was based on the release of reducing sugars from different seaweed groups in the saccharification process. The selected microbes significantly increased the release of reducing sugars compared to the control conditions in all three seaweed species, with significant differences (P<0.05) based on the media, microbes, seaweed species, processed condition, and days of hydrolysis. Factor analysis of mixed data indicated that microbes contributed to the maximum variability of the data. Vibrio parahaemolyticus caused the maximum biomass conversion ratio for reducing sugars from S. wightii (22.31 ± 0.65%) and U. fasciata (24.6 ± 1.28%) with an increment of 8.9% and 9.35%, respectively from control conditions. The maximum biomass conversion of G. corticata was 24.8 ± 0.51% following Bacillus amyloliquefaciens treatment with an increment of 6.39% from the control. Even though different combinations of three prioritized microbes produced better saccharification than the control conditions, individual use of prioritized microbes made a better release of reducing sugars. In brief, seaweed hydrolysis using the prioritized microbes of the present study can be applied to improve the saccharification process of seaweeds in an eco-friendly and less expensive platform. [ABSTRACT FROM AUTHOR]

Among several sustainable resources, marine heterotrophic microorganisms have gained much interest for various commercial applications owing to their potential to produce high quantities of polyunsaturated fatty acids. Above 70% of the globally produced fish oil is utilised for aqua feed formulations. Intense research is being carried out to find suitable alternatives to fish oil. Oleaginous protists are being explored as a promising substitute to fish oil and also for various high-value-added products. However, characterisation and utilisation of these unique protists remain underexplored in many countries including India and this prompted us to screen and isolate these heterotrophic microorganisms capable of producing PUFAs. In this study, 11 strains of heterotrophic thraustochytrid capable of producing significant quantities of polyunsaturated fatty acids were successfully isolated from different mangrove habitats along the southwest coast of India. Morphological characterisation along with molecular identification revealed that these strains showed close similarity to Aurantiochytrium spp. of the family Thraustochytridae. They are able to produce 7–11 g of dry biomass per litre of culture. Their fatty acid content was up to 12% (wt/wt) of biomass and GC analysis confirmed that these protists can accumulate docosahexaenoic acid as high as 22–60% of the total fatty acids. Their enzymatic activity, tolerance to various abiotic stress factors and antagonistic potential against vibrios are also described. These heterotrophic protists can antagonise aquaculture pathogens and act as an excellent source of docosahexaenoic acid that indicates their potential as a sustainable alternative to fish oil. [ABSTRACT FROM AUTHOR]