RESUMO
Agar and agarose have wide applications in food and pharmaceutical industries. Knowledge on the genome of red seaweeds that produce them is still lacking. To fill the gap in genome analyses of these red algae, we have sequenced the nuclear and organellar genomes of an agarophyte, Gracilaria changii. The partial nuclear genome sequence of G. changii has a total length of 35.8Mb with 10,912 predicted protein coding sequences. Only 39.4% predicted proteins were found to have significant matches to protein sequences in SwissProt. The chloroplast genome of G. changii is 183,855bp with a total of 201 open reading frames (ORFs), 29 tRNAs and 3 rRNAs predicted. Five genes: ssrA, leuC and leuD CP76_p173 (orf139) and pbsA were absent in the chloroplast genome of G. changii. The genome information is valuable in accelerating functional studies of individual genes and resolving evolutionary relationship of red seaweeds.
Assuntos
Genoma de Cloroplastos , Gracilaria/genética , Gracilaria/classificação , Anotação de Sequência Molecular , Fases de Leitura Aberta , Filogenia , RNA Ribossômico/genética , RNA de Transferência/genética , Homologia de Sequência , Sequenciamento Completo do GenomaRESUMO
While reliance on morphology has been at the expense of clearly distinguishing gracilarioid species, molecular data have proven to be more reliable in discriminating between taxa. Gracilariaphuquocensis was originally described, based on materials collected from Vietnam. Since it was described in 2020, there have been no further reports of this species. Meanwhile, a question has been raised as to whether the identity of a rhodophyte gracilarioid alga collected from the Philippines that has been referred to as an unidentified species of Gracilaria, could be G.phuquocensis. Based on comparative morpho-anatomical features and a molecular phylogeny based on rbcL gene sequences, establishing the identity of the Philippine material has led to the finding of the new record of G.phuquocensis outside its type locality. In addition to the discovery of G.phuquocensis in the Philippines, the species here is also identified as a newly-reported host for the adelphoparasite resembling Gracilariababae.
RESUMO
Currently, the demand in the food market for oligosaccharides with biological activities is rapidly increasing. In this study, agar polysaccharides from Gracilaria fisheri were treated with ß-agarases and hydrolyzed to agar oligosaccharides (AOSs). High-performance anion-exchange chromatography/pulsed amperometric detection (HPAEC-PAD), Fourier-transform infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC), were employed to analyze the chemical characteristics of AOSs. The FT-IR spectra revealed that the enzymatic hydrolysis had no effect on specific functional groups in the AOS molecule. To investigate the prebiotic and pathogen inhibitory effects of AOSs, the influence of AOSs on the growth of three probiotic and two pathogenic bacteria was examined. The gastrointestinal tolerance of probiotics in the presence of AOSs was also investigated. AOSs enhanced the growth of Lactobacillus plantarum by 254%, and inhibited the growth of Bacillus cereus by 32.80%, and Escherichia coli by 58.94%. The highest survival rates of L. plantarum and L. acidophilus were maintained by AOSs in the presence of α-amylase and HCl under simulated gastrointestinal conditions. This study demonstrates that AOSs from G. fisheri exhibit potential as a prebiotic additive in foods.
RESUMO
Gracilaria edulis is one of the most studied agarophytes, especially in tropical regions like India because of its natural abundance. Apart from the Indian peninsula, it is widely distributed in tropical and subtropical regions. The taxonomy of G. edulis is evolving; currently G. edulis is the taxonomically accepted name, however several phylogenetic and morphological investigations supported its inclusion in the genus Hydropuntia. In addition to the conventional farming methods like the tube net and raft methods which use clonally propagated seed material, spore-based planting materials like carpospores have been employed to cultivate G. edulis. Co-cultivation with shrimp farm wastewater has also been practised to make the cultivation economically viable and environmentally sustainable as the seaweed could provide an efficient ecosystem service by up taking nitrogen from the shrimp waste. Like other seaweed cultivation systems, farming of G. edulis is also infested by various epiphytes like Ulva, Cladophora, Ceramium, Centroceras, Hypnea and Padina as well as grazed by fishes like Monodactylus, Pelates and Pteroscirtes which decrease the growth and ultimately result in low yield of agar, seaweed sap and other value added products. Food grade agar produced by this seaweed is an important resource and the current review focusses on the latest extraction technologies. Further, there also is evidence based application of plant bio-stimulant derived from G. edulis feedstock which has proven to be highly effective in enhancing the yield by 10-33% in field trials of nine cash crops. Supplementary Information: The online version contains supplementary material available at 10.1007/s10811-023-02955-8.