Meta-analysis of transcriptomic profiles in Dunaliella tertiolecta reveals molecular pathway responses to different abiotic stresses.

Microalgae are photosynthetic organisms and a potential source of sustainable metabolite production. However, different stress conditions might affect the production of various metabolites. In this study, a meta-analysis of RNA-seq experiments in Dunaliella tertiolecta was evaluated to compare metabolite biosynthesis pathways in response to abiotic stress conditions such as high light, nitrogen deficiency and high salinity. Results showed downregulation of light reaction, photorespiration, tetrapyrrole and lipid-related pathways occurred under salt stress. Nitrogen deficiency mostly induced the microalgal responses of light reaction and photorespiration metabolism. Phosphoenol pyruvate carboxylase, phosphoglucose isomerase, bisphosphoglycerate mutase and glucose-6-phosphate-1-dehydrogenase (involved in central carbon metabolism) were commonly upregulated under salt, light and nitrogen stresses. Interestingly, the results indicated that the meta-genes (modules of genes strongly correlated) were located in a hub of stress-specific protein-protein interaction (PPI) network. Module enrichment of meta-genes PPI networks highlighted the cross-talk between photosynthesis, fatty acids, starch and sucrose metabolism under multiple stress conditions. Moreover, it was observed that the coordinated expression of the tetrapyrrole intermediated with meta-genes was involved in starch biosynthesis. Our results also showed that the pathways of vitamin B6 metabolism, methane metabolism, ribosome biogenesis and folate biosynthesis responded specifically to different stress factors. Since the results of this study revealed the main pathways underlying the abiotic stress, they might be applied in optimised metabolite production by the microalga Dunaliella in future studies. PRISMA check list was also included in the study.

Biochemical profiling of three indigenous Dunaliella isolates with main focus on fatty acid composition towards potential biotechnological application.

This study describes the biochemical composition of three isolates, Dunaliella sp. ABRIINW-B1, -G2/1 and -I1 towards the biotechnological potential. Dunaliella sp. ABRIINW- G2/1 and -I1 had a remarkable protein content (∼40% dry weight). Dunaliella sp. ABRIINW-I1 contained a pigment fraction of 3.2% largely composed of chlorophyll a (1.9%) and carotenoid (1.1%). Dunaliella sp. ABRIINW-B1, -G2/1 and -I1 produced respectively 42, 36 and 47% lipid content. The occurrence of high lipid and low carbohydrate (4-7%) in the isolates demonstrated their cell tendency to store energy and carbon mainly in lipid form. The lipid profile of the isolates expressed adequate n3:n6 ratio and health indices. The biochemical analysis revealed that Dunaliella sp. ABRIINW-B1 and -G2/1 have potential applications in the food and freshwater aquafeed sector. While Dunaliella sp. ABRIINW-I1 owing to appropriate pigment, protein, and lipid level containing very-long-chain polyunsaturated fatty acids showed a great promise in nutritional, pharmaceutical and marine aquafeed industries.

Genetic and in silico analysis of plantaricin EFI locus in indigenous isolates of lactobacillus plantarum.

Genetic investigation and in silico analysis of plantaricin EFI (plnEFI) locus was performed in three indigenous isolates of Lactobacillus plantarum EL3, L28 and BL1. Amplification with plnEFI specific primers and production of ~ 10 KDa size protein suggested the existence of class II bacteriocins. The analysis demonstrated that the studied fragment included structural bacteriocin, immunity, partial transporter and potential regulatory encoding regions. Based on the results, there was one DNA polymorphic site in plnE as well as plnF of the studied sequences. One nucleotide substitution in plnE of BL1 isolate lead to replacement of Glycin with Valine. These two are of non-polar type which did not affect instability index of plnE protein. The only nucleotide variation in plnF of EL3 isolate did not change the amino acid sequence since the modified nucleotide constituted alternative codon of the original amino acid. The highest DNA polymorphism occurred in the region with immunity function which in BL1 resulted in the conversion of start codon to amino acid codon. In the partial transporter sequence, one variable nucleotide site caused amino acid replacement in all the isolates which elevated stability of N-terminal domain in the transporter protein compared to nominated reference isolate L. plantarum C11. The region with possible regulatory function was identical in all three isolates. © 2018 American Institute of Chemical Engineers Biotechnol Progress, 35: e2773, 2019.