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As seawater temperature rises, repeated thermal bleaching events have negatively affected the reefs of the Andaman Sea for over decades. Studies on the coral-associated microbial diversity of prokaryotes and microbial eukaryotes (microbiome) in healthy and bleached corals are important to better understand the coral holobionts that involved augmented resistance to stresses, and this information remains limited in the Andaman Sea of Thailand. The present study thereby described the microbiomes of healthy (unbleached) and bleached colonies of four prevalent corals, Acropora humilis, Platygyra sp., Pocillopora damicornis, and Porites lutea, along with the surrounding seawater and sediments, that were collected during a 2016 thermal bleaching event, using 16S and 18S rRNA genes next-generation sequencing (NGS). Both prokaryotic and eukaryotic microbes showed isolated community profiles among sample types (corals, sediment, and seawater) [analysis of similarities (ANOSIM): p = 0.038 for prokaryotes, p < 0.001 for microbial eukaryotes] and among coral genera (ANOSIM: p < 0.001 for prokaryotes and microbial eukaryotes). In bleached state corals, we found differences in microbial compositions from the healthy state corals. Prevalent differences shared among bleached coral genera (shared in at least three coral genera) included a loss of reported coral-beneficial microbes, such as Pseudomonadales, Alteromonadales, and Symbiodinium; meanwhile an increase of putative coral-pathogenic Malassezia and Aspergillus. This difference could affect carbon and nitrogen availability for coral growth, reflective of a healthy or bleached state. Our findings in part supported previously microbial dysbiosis knowledge of thermal bleaching coral microbiomes around South East Asia marine geography, and together ongoing efforts are to support the understanding and management of microbial diversity to reduce the negative impacts to corals in massive thermal bleaching events.

Clostridioides difficileis a major cause of diarrhea in patients with antibiotic administration.Lacticaseibacillus caseiT21, isolated from a human gastric biopsy, was tested in a murineC. difficileinfection (CDI) model and colonic epithelial cells (Caco-2 and HT-29). Daily administration ofL. caseiT21 [1 × 108colony forming units (CFU)/dose] for 4 days starting at 1 day beforeC. difficilechallenge attenuated CDI as demonstrated by a reduction in mortality rate, weight loss, diarrhea, gut leakage, gut dysbiosis, intestinal pathology changes, and levels of pro-inflammatory cytokines [interleukin (IL)-1β, tumor necrosis factor (TNF)-α, macrophage inflammatory protein 2 (MIP-2), and keratinocyte chemoattractant (KC)] in the intestinal tissue and serum. Conditioned media fromL. caseiT21 exerted biological activities that fight againstC. difficileas demonstrated in colonic epithelial cells by the following: (i) suppression of gene expression and production of IL-8, an important chemokine involved inC. difficilepathogenesis, (ii) reduction in the expression ofSLC11A1(solute carrier family 11 member 1) andHuR(human antigen R), important genes for the lethality ofC. difficiletoxin B, (iii) augmentation of intestinal integrity, and (iv) up-regulation ofMUC2, a mucosal protective gene. These results supported the therapeutic potential ofL. caseiT21 for CDI and the need for further study on the intervention capabilities of CDI.

Global warming has caused elevated seawater temperature and coral bleaching, including events on shallow reefs in the upper Gulf of Thailand (uGoT). Previous studies have reported an association between loss of zooxanthellae and coral bleaching. However, studies on the microbial diversity of prokaryotes and eukaryotes (microbiome) as coral holobionts are also important and this information is still limited in the uGoT. To address this shortcoming, this report provided baseline information on the prokaryotic (bacteria and archaea) and eukaryotic microbes of healthy and bleached colonies of four prevalent corals Acropora humilis, Acropora millepora, Platygyra sinensis, and Porites lutea and surrounding seawater and sediments, using 16S and 18S rRNA gene next-generation sequencing. Both prokaryotic and eukaryotic microbes showed isolated community profiles among sample types (corals, sediment, and seawater) (ANOSIM: P < 0.001, R = 0.51 for prokaryotic profiles and P < 0.001, R = 0.985 for eukaryotic microbe profiles). Among coral species, P. sinensis showed the most diverse prokaryotic community compared with the others (ANOSIM: P < 0.001, R = 0.636), and P. lutea showed the most diverse eukaryotic microbes (P = 0.014, R = 0.346). Healthy and bleached corals had some different microbiomes in species and their prevalences. For instance, the significant increase of Alphaproteobacteria in P. sinensis resulted in reduced prokaryotic community evenness and altered potential metabolic profiles (i.e., increased amino acid metabolism and genetic information processing and transcription, but decreased prokaryotic functions in cell motility, signaling, and transduction). For eukaryotic microbes, the loss of the algal Symbiodinium (colloquially known as zooxanthellae) in bleached corals such as P. lutea resulted in increased Chromista and Protista and, hence, clearly distinct eukaryotic microbe (including fungi) communities in healthy vs. bleached colonies of corals. Bleached corals were enriched in bacterial pathogens (e.g., Acinetobacter, Helicobacter, Malassesia, and Aspergillus) and decreased coral-beneficial prokaryotic and eukaryotic microbes (e.g., Rhizobiales and Symbiodinium). Additionally, this study identified microbiome species in bleached P. lutea that might help bleaching recovery (e.g., high abundance of Rhizobiales, Oceanospirillales, Flavobacteriales, and Alteromonadales). Overall, our coral-associated microbiome analyses identified altered diversity patterns of bacteria, archaea, fungi, and eukaryotic microbes between healthy and bleached coral species that are prevalent in the uGoT. This knowledge supports our ongoing efforts to manipulate microbial diversity as a means of reducing the negative impacts of thermal bleaching events in corals inhabiting the uGoT.

The southeast Andaman Sea 52-m off the west coast of Phang Nga province, Thailand, is located in the Indian Ocean, representing a hotspot for marine biodiversity of the world. This study utilized metagenomics combined 16S rRNA gene (V3–V4) sequencing, and firstly revealed the microbiota and their metabolism potentials of this site at an epipelagic depth (150-m depth, TC150M), including comparison with its pelagic depth (30-m depth, TC30M) as well as other nearby Thailand and global ocean sites. Between TC150M and TC30M, the TC150M microbial metagenomics was an eight-fold higher, and the microbiota comprised, for examples more abundant Bacteroidetes while fewer Proteobacteria, than the TC30M. The microbial metabolic potentials of the TC150M were statistically higher in replication repair and metabolisms of amino acids, lipids, nucleotides, and xenobiotics biodegradation, etc. Following comparative microbiota analyses between three Andaman Sea sites and two Gulf of Thailand sites, the relatively great proportions of Bacteroidetes, Nitrospirae, Gemmatimonadetes, and Chlorobi characterized the southeast Andaman Sea. Nevertheless, the microbiota representing Thailand marine sites remained distinguished from the global ocean sites where beta diversities were close. Thai maritime sites showed proportionally higher Proteobacteria, Bacteroides, Nitrospirae, Gemmatimonadetes, and Chlorobi. Thus, the Thai marine microbiota database helps better understand our global ocean microbiota and microbial metabolic potentials. Here, the microbial metabolism potentials between Thailand and the global ocean sites of relatively close microbiota databases encompose the similar functions yet in statistically different frequencies. Our research provided the first preliminary marine microbiome comparison between the epipelagic and pelagic sea levels of the southeast Andaman Sea, Thailand.

Tha Wang coast in Sichang island, Chonburi province, Thailand, serves a major pier, cargo transportation and is populated with anthropogenic activities. Hence, monitoring of environmental status, in part by microbial diversity, is essential. Previously, the coastal marine microbiota of this area in a dry season (February 2011) had been reported, but the database for a wet season is none. As marine microbiota in several sites were reported fluctuate between dry and wet seasons, specifically in the 2011 that one of the largest flood in Thailand history even occurred from July 2011 to January 2012; the present study thereby first revealed the coastal Sichang water microbiota in the 2011 wet season (July 2011) using metagenomic derived 16S rRNA gene sequencing. Wet and dry seasons showed differences in prokaryotic community richness and evenness: community similarity indices by Jaccard, Lennon, and Yue and Clayton were 2.06–58.28%. This resulted in differences in metabolic potentials, for instances the lower metabolisms for energy and nutrient cycling but the greater in pathogenesis in wet season. Our data were also compared against the flooding water microbiota nearby to Chonburi province to observe any possible correlation; and the coastal Sichang was found distinct given diverse sources of flooding water and local contamination might affect the diversity. In conclusion, this wet-season microbiota supported the better knowledge on the seasonal microbiota of coastal Sichang island.