Machine learning framework for gut microbiome biomarkers discovery and modulation analysis in large-scale obese population.

BACKGROUND: The gut microbiome has proven to be an important factor affecting obesity; however, it remains a challenge to identify consistent biomarkers across geographic locations and perform precisely targeted modulation for obese individuals. RESULTS: This study proposed a systematic machine learning framework and applied it to 870 human stool metagenomes across five countries to obtain comprehensive regional shared biomarkers and conduct a personalized modulation analysis. In our pipeline, a heterogeneous ensemble feature selection diagram is first developed to determine an optimal subset of biomarkers through the aggregation of multiple techniques. Subsequently, a deep reinforcement learning method was established to alter the targeted composition to the desired healthy target. In this manner, we can realize personalized modulation by counterfactual inference. Consequently, a total of 42 species were identified as regional shared biomarkers, and they showed good performance in distinguishing obese people from the healthy group (area under curve (AUC) =0.85) when demonstrated on validation datasets. In addition, by pooling all counterfactual explanations, we found that Akkermansia muciniphila, Faecalibacterium prausnitzii, Prevotella copri, Bacteroides dorei, Bacteroides eggerthii, Alistipes finegoldii, Alistipes shahii, Eubacterium sp. _CAG_180, and Roseburia hominis may be potential broad-spectrum targets with consistent modulation in the multi-regional obese population. CONCLUSIONS: This article shows that based on our proposed machine-learning framework, we can obtain more comprehensive and accurate biomarkers and provide modulation analysis for the obese population. Moreover, our machine-learning framework will also be very useful for other researchers to further obtain biomarkers and perform counterfactual modulation analysis in different diseases.

A multiphase dietetic protocol incorporating an improved ketogenic diet enhances weight loss and alters the gut microbiome of obese people.

The prevalence of obesity and its associated diseases is increasing. In the current study, 15 obese subjects took part in a 12-week multiphase dietetic protocol incorporating an improved ketogenic diet (MDP-i-KD) (KYLLKS 201806). We investigated the effects of the MDP-i-KD on the anthropometric parameters and the gut microbiota of obese subjects. Our results showed that the MDP-i-KD led to significant reductions in body mass index in obese subjects. The MDP-i-KD significantly decreased the relative abundance of the Lachnospiraceae_ND3007_group, the Eubacterium_hallii_group, and Pseudomonas and Blautia. In addition, gut microbiota co-occurrence networks in obese subjects were restructured to a more healthy condition after weight loss. These results show that the MDP-i-KD enhanced weight loss, which may be associated with dietary-induced changes in the gut microbiome. Our results emphasise the importance of determining the interaction between the host and microbial cells to comprehensively understand the mechanism by which diet affects host physiology and the microbiota.

Lactic acid bacteria that activate immune gene expression in Caenorhabditis elegans can antagonise Campylobacter jejuni infection in nematodes, chickens and mice.

BACKGROUND: Campylobacter jejuni is the major micro-bacillary pathogen responsible for human coloenteritis. Lactic acid bacteria (LAB) have been shown to protect against Campylobacter infection. However, LAB with a good ability to inhibit the growth of C. jejuni in vitro are less effective in animals and animal models, and have the disadvantages of high cost, a long cycle, cumbersome operation and insignificant immune response indicators. Caenorhabditis elegans is increasingly used to screen probiotics for their anti-pathogenic properties. However, no research on the use of C. elegans to screen for probiotic candidates antagonistic to C. jejuni has been conducted to date. RESULTS: This study established a lifespan model of C. elegans, enabling the preselection of LAB to counter C. jejuni infection. A potential protective mechanism of LAB was identified. Some distinct LAB species offered a high level of protection to C. elegans against C. jejuni. The LAB strains with a high protection rate reduced the load of C. jejuni in C. elegans. The transcription of antibacterial peptide genes, MAPK and Daf-16 signalling pathway-related genes was elevated using the LAB isolates with a high protection rate. The reliability of the lifespan model of C. elegans was verified using mice and chickens infected with C. jejuni. CONCLUSIONS: The results showed that different LAB had different abilities to protect C. elegans against C. jejuni. C. elegans provides a reliable model for researchers to screen for LAB that are antagonistic to C. jejuni on a large scale.

Targeting the Gut Microbiota for Remediating Obesity and Related Metabolic Disorders.

The rate of obesity is rapidly increasing and has become a health and economic burden worldwide. As recent studies have revealed that the gut microbiota is closely linked to obesity, researchers have used various approaches to modulate the gut microbiota to treat the condition. Dietary composition and energy intake strongly affect the composition and function of the gut microbiota. Intestinal microbial changes alter the composition of bile acids and fatty acids and regulate bacterial lipopolysaccharide production, all of which influence energy metabolism and immunity. Evidence also suggests that remodeling the gut microbiota through intake of probiotics, prebiotics, fermented foods, and dietary plants, as well as by fecal microbiota transplantation, are feasible methods to remediate obesity.

Roles of intestinal bacteroides in human health and diseases.

Bacteroides, an abundant genus in the intestines of mammals, has been recently considered as the next generation probiotics (NGP) candidate due to its potential role in promoting host health. However, the role of Bacteroides in the development of intestinal dysfunctions such as diarrhea, inflammatory bowel disease, and colorectal cancer should not be overlooked. In the present study, we focused on nine most widely occurred and abundant Bacteroides species and discussed their roles in host immunity, glucose and lipid metabolism and the prevention or induction of diseases. Besides, we also discussed the current methods used in the safety evaluation of Bacteroides species and key opinions about the concerns of these strains for the future use.

Both living and dead Faecalibacterium prausnitzii alleviate house dust mite-induced allergic asthma through the modulation of gut microbiota and short-chain fatty acid production.

BACKGROUND: Asthma is increasingly prevalent worldwide, and novel strategies to prevent or treat this disease are needed. Probiotic intervention has recently been reported to be effective for asthma prevention. Here, we explored the effects of Faecalibacterium prausnitzii on the development of allergic airway inflammation in a murine model of house dust mite (HDM)-induced allergic asthma. RESULTS: Supplementation with living and dead F. prausnitzii blocked eosinophil, neutrophil, lymphocyte and macrophage influx and alleviated the pathological changes. Moreover, both living and dead F. prausnitzii administration decreased the levels of interleukin (IL)-4, IL-5, IL-13 and immunoglobulin G1, elevated regulatory T cell (Tregs) ratio, improved microbial dysbiosis and enhanced short-chain fatty acid (SCFA) production. Network correlation analysis revealed that the immune indicators were strongly associated with SCFA production. Based on the linear discriminant analysis effect size, Turicibacter was found to be the core genus related to HDM-induced asthma. Living F. prausnitzii treatment enriched Faecalibaculum, Dubosiella and Streptococcus, while dead F. prausnitzii treatment increased Muribaculaceae and Parabacteroides. Interestingly, both living and dead F. prausnitzii administration enriched Lachnoclostridium and normalized the pathways involving carbohydrate and lipid metabolism, which might be related to SCFA production. CONCLUSION: Faecalibacterium prausnitzii exerts an anti-asthmatic effect partly by gut microbiota modulation and SCFA production, suggesting its potential as a probiotic agent for allergic asthma prevention. © 2021 Society of Chemical Industry.

Bifidobacteria adolescentis regulated immune responses and gut microbial composition to alleviate DNFB-induced atopic dermatitis in mice.

PURPOSE: Emerging studies have reported gut microbial composition plays a key role in alleviating AD clinical symptoms during the probiotic intervention, but the correlation among clinical symptoms, immune responses and gut microbial alteration needs to be explored. Therefore, the objective was to investigate the correlation during Bifidobacterium adolescentis intervention in DNFB-induced AD mice. METHODS: The mice were randomly divided into nine groups and fed B. adolescentis for 3 weeks. At the end of the experiment, clinical and immune indicators were assessed. Flow cytometry was performed to explore the effect of B. adolescentis on regulatory T cells in the spleen. V3-V4 region of the 16S ribosomal RNA (rRNA) gene was sequenced to evaluate changes in the gut microbiota. RESULTS: Bifidobacteria adolescentis treatments reduced ear and skin thickness and suppressed eosinophils and mast cells infiltration. Th1- and Th2-type responses were regulated and the Tregs population was promoted in the spleen by B. adolescentis treatments. Bifidobacteria adolescentis increased the relative abundance of Lactobacillus but decrease Dorea and Pediococcus. Propionic and butyric acids were increased but isovaleric acid was decreased by B. adolescentis treatment. Besides, the functional modules, such as fatty acid biosynthesis, antigen processing and presentation were upregulated by B. adolescentis Ad1 treatment compared to the DNFB group. CONCLUSION: Collectively, these results imply that B. adolescentis with the role of immunomodulation promotes Treg differentiation and suppresses Th2 responses, and increases the proportion of Lactobacillus that is positively correlated to increase in propionic acid production, and thus has the potential for AD amelioration.

Microbial diversity and volatile profile of traditional fermented yak milk.

Previous research reported that fermented yak milk had a diverse microbial composition. For this study, raw yak milk, qula, and fermented yak milk samples were collected from the Aba Tibetan autonomous region of China. The genus and species microbial composition of these samples were analyzed by high-throughput sequencing of 16S rRNA and groEL gene amplicons, and the volatile profile of the samples was quantified by gas chromatography-mass spectrometry. The results indicated variation in abundance of microbiota at the genus level among the fermented yak milk samples, with Lactobacillus as the most abundant genus in the majority of samples, ranging from 41.6 to 98.3%. The volatile profile of the samples varied among those collected from different villages. Correlations between bacterial composition and volatile compounds of the samples were also observed. Lactobacillus displayed a significant correlation with volatile compounds such as benzaldehyde, 2,3-pentanedione, ethanol, and ethyl acetate, whereas the samples with relatively high abundance of Streptococcus and Lactococcus displayed relatively low contents of volatile compounds.

The liver-gut microbiota axis modulates hepatotoxicity of tacrine in the rat.

The gut microbiota possesses diverse metabolic activities, but its contribution toward heterogeneous toxicological responses is poorly understood. In this study, we investigated the role of the liver-gut microbiota axis in underpinning the hepatotoxicity of tacrine. We employed an integrated strategy combining pharmacokinetics, toxicology, metabonomics, genomics, and metagenomics to elucidate and validate the mechanism of tacrine-induced hepatotoxicity in Lister hooded rats. Pharmacokinetic studies in rats demonstrated 3.3-fold higher systemic exposure to tacrine in strong responders that experienced transaminitis, revealing enhanced enterohepatic recycling of deglucuronidated tacrine in this subgroup, not attributable to variation in hepatic disposition gene expression. Metabonomic studies implicated variations in gut microbial activities that mapped onto tacrine-induced transaminitis. Metagenomics delineated greater deglucuronidation capabilities in strong responders, based on differential gut microbial composition (e.g., Lactobacillus, Bacteroides, and Enterobacteriaceae) and approximately 9% higher ß-glucuronidase gene abundance compared with nonresponders. In the validation study, coadministration with oral ß-glucuronidase derived from Escherichia coli and pretreatment with vancomycin and imipenem significantly modulated the susceptibility to tacrine-induced transaminitis in vivo. CONCLUSION: This study establishes pertinent gut microbial influences in modifying the hepatotoxicity of tacrine, providing insights for personalized medicine initiatives. (Hepatology 2018;67:282-295).

Bifidobacterium and Lactobacillus Composition at Species Level and Gut Microbiota Diversity in Infants before 6 Weeks.

Our objective was to investigate the effects of different delivery and feeding modes on the gut microbiota composition of early infants with special emphasis on Bifidobacterium and Lactobacillus profiles at species level. 16S rRNA V3-V4 regions, bifidobacterial, and lactobacilli groEL genes from infant feces were sequenced by Illumina MiSeq. Gut microbiota abundance was significantly different, where standard vaginally delivered (SVD) and breast-fed (BF) groups were higher in comparison with caesarean section (CS), milk-powder-fed (MPF), and mixed-fed (MF) groups. The genus unclassified Enterobacteriaceae was dominant, followed by Bifidobacterium, which was highly abundant in SVD and BF groups. The dominant Bifidobacterium species in all groups were B. longum subsp. longum, B. longum subsp. infantis and B. animalis subsp. lactis. B. dentium and the diversity of Bifidobacterium in SVD and BF groups were significantly higher. For Lactobacillus profiles, L. rhamnosus and L. gasseri were dominant among all the groups, while Lactobacillus species in CS and MPF groups were more diverse. Functional predictions showed significant differences between delivery mode and feeding groups, such as phosphotransferase system as well as taurine and hypotaurine metabolism. In early infants with different delivery and feeding methods, gut microbiota-particularly bifidobacteria and lactobacilli communities-showed significant differences, with strong implications for physiological functions.

Exploring the transcriptome of non-model oleaginous microalga Dunaliella tertiolecta through high-throughput sequencing and high performance computing.

BACKGROUND: RNA-Seq technology has received a lot of attention in recent years for microalgal global transcriptomic profiling. It is widely used in transcriptome-wide analysis of gene expression., particularly for microalgal strains with potential as biofuel sources. However, insufficient genomic or transcriptomic information of non-model microalgae has limited the understanding of their regulatory mechanisms and hampered genetic manipulation to enhance biofuel production. As such, an optimal microalgal transcriptomic database construction is a subject of urgent investigation. RESULTS: Dunaliella tertiolecta, a non-model oleaginous microalgal species, was sequenced via Illumina MISEQ and HISEQ 4000 in RNA-Seq studies. The high quality high-throughout sequencing data were explored using high performance computing (HPC) in a petascale data center and subjected to de novo assembly and parallelized mpiBLASTX search with multiple species. As a result, a transcriptome database of 17,845 was constructed (~95% completeness). This enlarged database constructed fueled the RNA-Seq data analysis, which was validated by a nitrogen deprivation (ND) study that induces triacylglycerol (TAG) production. CONCLUSIONS: The new paralleled assembly and annotation method under HPC presented here allows the solution of large-scale data processing problems in acceptable computation time. There is significant increase in the number of transcriptomic data achieved and observable heterogeneity in the performance to identify differentially expressed genes in the ND treatment paradigm. The results provide new insights as to how response to ND treatment in microalgae is regulated. ND analyses highlight the advantages of this database generated in this study that could also serve as a useful resource for future gene manipulation and transcriptome-wide analysis. We thus demonstrate the usefulness of exploring the transcriptome as an informative platform for functional studies and genetic manipulations in similar species.

Elevated acetyl-CoA by amino acid recycling fuels microalgal neutral lipid accumulation in exponential growth phase for biofuel production.

Microalgal neutral lipids [mainly in the form of triacylglycerols (TAGs)], feasible substrates for biofuel, are typically accumulated during the stationary growth phase. To make microalgal biofuels economically competitive with fossil fuels, generating strains that trigger TAG accumulation from the exponential growth phase is a promising biological approach. The regulatory mechanisms to trigger TAG accumulation from the exponential growth phase (TAEP) are important to be uncovered for advancing economic feasibility. Through the inhibition of pyruvate dehydrogenase kinase by sodium dichloroacetate, acetyl-CoA level increased, resulting in TAEP in microalga Dunaliella tertiolecta. We further reported refilling of acetyl-CoA pool through branched-chain amino acid catabolism contributed to an overall sixfold TAEP with marginal compromise (4%) on growth in a TAG-rich D. tertiolecta mutant from targeted screening. Herein, a three-step α loop-integrated metabolic model is introduced to shed lights on the neutral lipid regulatory mechanism. This article provides novel approaches to compress lipid production phase and heightens lipid productivity and photosynthetic carbon capture via enhancing acetyl-CoA level, which would optimize renewable microalgal biofuel to fulfil the demanding fuel market.

The role of micronutrients and strategies for optimized continual glycerol production from carbon dioxide by Dunaliella tertiolecta.

The microalga Dunaliella tertiolecta synthesizes intracellular glycerol as an osmoticum to counteract external osmotic pressure in high saline environments. The species has recently been found to release and accumulate extracellular glycerol, making it a suitable candidate for sustainable industrial glycerol production if a sufficiently high product titre yield can be achieved. While macronutrients such as nitrogen and phosphorus are essential and well understood, this study seeks to understand the influence of the micronutrient profile on glycerol production. The effects of metallic elements calcium, magnesium, manganese, zinc, cobalt, copper, and iron, as well as boron, on glycerol production as well as cell growth were quantified. The relationship between cell density and glycerol productivity was also determined. Statistically, manganese recorded the highest improvement in glycerol production as well as cell growth. Further experiments showed that manganese availability was associated with higher superoxide dismutase formation, thus suggesting that glycerol production is negatively affected by oxidative stress and the manganese bound form of this enzyme is required in order to counteract reactive oxygen species in the cells. A minimum concentration of 8.25 × 10(-5) g L(-1) manganese was sufficient to overcome this problem and achieve 10 g L(-1) extracellular glycerol, compared to 4 g L(-1) without the addition of manganese. Unlike cell growth, extracellular glycerol production was found to be negatively affected by the amount of calcium present in the normal growth medium, most likely due to the lower cell permeability at high calcium concentrations. The inhibitory effects of iron also affected extracellular glycerol production more significantly than cell growth and several antagonistic interaction effects between various micronutrients were observed. This study indicates how the optimization of these small amounts of nutrients in a two-stage system can lead to a large enhancement in D. tertiolecta glycerol production and should be considered during the design of a large scale bioprocess for this alternative route to glycerol.

RNA-Seq reveals transcriptomic interactions of Bacillus subtilis natto and Bifidobacterium animalis subsp. lactis in whole soybean solid-state co-fermentation.

Bifidobacteria are anaerobes and are difficult to culture in conventional fermentation system. It was observed that Bacillus subtilis natto enhanced growth of Bifidobacterium animalis subsp. lactis v9 by about 3-fold in a whole soybean solid-state co-fermentation, in a non-anaerobic condition. For the purpose of understanding the metabolic interactions between Bif. animalis subsp. lactis v9 and Ba. subtilis natto, the transcriptome of Bif. animalis subsp. lactis v9 and Ba. subtilis natto was analyzed in single and mixed cultures using RNA-Seq. Compared with the single culture, 459 genes of Bif. animalis subsp. lactis v9 were up regulated and 21 were down regulated in the mixed culture with Ba. subtilis natto, with more than 2-fold difference. Predictive metagenomic analyses suggested that Ba. subtilis natto up regulated transport functions, complex carbohydrates and amino acid metabolism, DNA repair, oxydative stress-related functions, and cell growth of Bif. animalis subsp. lactis v9. In the mixed culture with Bif. animalis subsp. lactis v9, only 3 transcripts of Ba. subtilis natto were over-expressed and 3115 were under-expressed with more than 2-fold difference. The highest down-regulated genes were those involved in carbohydrate and amino acid metabolism. The data presented here demonstrated a parasitic-like interaction regulated at the transcription level, between Ba. subtilis natto and Bif. animalis subsp. lactis in the mixed culture. The over-expression of genes involved in substrate uptake and metabolism in Bif. animalis subsp. lactis in the mixed culture nevertheless, led to its higher cell concentration in the nutrient rich whole soybean medium.

Gut microbiome signatures associated with type 2 diabetes in obesity in Mongolia.

Mongolian people possess a unique dietary habit characterized by high consumption of meat and dairy products and fewer vegetables, resulting in the highest obesity rate in East Asia. Although obesity is a known cause of type 2 diabetes (T2D), the T2D rate is moderate in this population; this is known as the "Mongolian paradox." Since the gut microbiota plays a key role in energy and metabolic homeostasis as an interface between food and body, we investigated gut microbial factors involved in the prevention of the co-occurrence of T2D with obesity in Mongolians. We compared the gut microbiome and metabolome of Mongolian adults with obesity with T2D (DO: n = 31) or without T2D (NDO: n = 35). Dysbiotic signatures were found in the gut microbiome of the DO group; lower levels of Faecalibacterium and Anaerostipes which are known as short-chain fatty acid (SCFA) producers and higher levels of Methanobrevibacter, Desulfovibrio, and Solobacterium which are known to be associated with certain diseases. On the other hand, the NDO group exhibited a higher level of fecal SCFA concentration, particularly acetate. This is consistent with the results of the whole shotgun metagenomic analysis, which revealed a higher relative abundance of SCFA biosynthesis-related genes encoded largely by Anaerostipes hadrus in the NDO group. Multiple logistic regression analysis including host demographic parameters indicated that acetate had the highest negative contribution to the onset of T2D. These findings suggest that SCFAs produced by the gut microbial community participate in preventing the development of T2D in obesity in Mongolians.

Inoculation of Latilactobacillus sakei with Pichia kluyveri or Saccharomyces boulardii improves flavor compound profiles of salt-free fermented wheat-gluten: Effects from single strain inoculation.

Wheat-gluten, the protein-rich portion of wheat, can be processed to produce a highly savory sauce product after solid and liquid-state fermentation (SSF and LSF) with the inoculation of selected lactic acid bacteria (LAB) and yeast under salt-free condition. However, limited research has been done on the impact of different types of microbes in this process. This work studied the flavour impact on fermented wheat-gluten by the single inoculation of Latilactobacillus sakei or one yeast (Saccharomyces boulardii or Pichia kluyveri). Glucose was depleted during LSF in all treatments. Lactic acid production increased over time in L. sakei-fermented samples but not in yeast-fermented samples. Cysteine, serine and arginine remained low over LSF in L. sakei-fermented samples but increased in yeast-fermented samples. More fruity esters such as isoamyl acetate and isobutyl acetate were detected in samples fermented by P. kluyveri, while S. boulardii boosted the production of alcohols such as 3-methyl butanol and 2-phenylethyl alcohol. Principal component analysis revealed a clear difference in volatile profiles of the samples fermented with different strains. Therefore, the fermented sauce can potentially be processed into different flavor directions, and based on the flavor profile, be used in different food applications.

Influence of Lactose Supplementation on Regulation of Streptococcus thermophilus on Gut Microbiota.

It has been found that Streptococcus thermophilus (S. thermophilus) influenced the gut microbiota and host metabolism with strain specificity in C57BL/6J mice in the previous study, though it remains unclear whether lactose as a dietary factor associated with dairy consumption is involved as the mediator in the interaction. In the present study, integrated analysis of 16S rRNA gene sequencing and untargeted metabolomics by liquid chromatography-mass spectrometry of fecal samples in C57BL/6J mice was applied to evaluate the effect of lactose on the regulation of gut microbiota by two S. thermophilus strains (4M6 and DYNDL13-4). The results showed that the influence of lactose supplementation on gut microbiota induced by S. thermophilus ingestion was strain-specific. Although two S. thermophilus strains ingestion introduced similar perturbations in the fecal microbiota and gut microbial metabolism, the regulation of DYNDL13-4 on the gut microbiota and metabolism was more affected by lactose than 4M6. More specifically, lactose and 4M6 supplementation mainly enriched pathways of d-glutamine and d-glutamate metabolism, alanine, aspartate, and glutamate metabolism, and tryptophan and phenylalanine metabolism in the gut, whereas 4M6 only enriched tryptophan and phenylalanine metabolism. DYNDL13-4-L (DYNDL13-4 with lactose) had significant effects on sulfur, taurine, and hypotaurine metabolism in the gut and on phenylalanine, tyrosine, tryptophan biosynthesis, and linoleic acid metabolism in serum relative to the DYNDL13-4. Our study demonstrated the strain-specific effect of lactose and S. thermophilus supplementation on gut microbiota and host metabolism. However, considering the complexity of the gut microbiota, further research is necessary to provide insights to facilitate the design of personalized fermented milk products as a dietary therapeutic strategy for improving host health.

ERp29 induces breast cancer cell growth arrest and survival through modulation of activation of p38 and upregulation of ER stress protein p58IPK.

Endoplasmic reticulum protein 29 (ERp29) is an ER luminal protein that has a role in protein unfolding and secretion, but its role in cancer is unclear. Recently, we reported that overexpression of ERp29 significantly inhibited cell proliferation and prevented tumorigenesis in highly proliferative MDA-MB-231 breast cancer cells. Here, we show that ERp29-induced cancer cell growth arrest is modulated by the interplay between the concomitant phosphorylation of p38 and upregulation of the inhibitor of the interferon-induced, double-stranded RNA-activated protein kinase, p58(IPK). In this cell model, ERp29 overexpression significantly downregulates modulators of cell proliferation, namely urokinase plasminogen activator receptor, ß(1)-integrin and epidermal growth factor receptor. Furthermore, ERp29 significantly (P<0.001) increases phosphorylation of p38 (p-p38) and reduces matrix metalloproteinase-9 secretion. The role of ERp29 in upregulating cyclin-dependent kinase inhibitors (p15 and p21) and in downregulating cyclin D(2) is demonstrated in slowly proliferating ERp29-overexpressing MDA-MB-231 cells, whereas the opposite response was observed in ERp29-knockdown MCF-7 cells. Pharmacological inhibition of p-p38 downregulates p15 and p21 and inhibits eIF2α phosphorylation, indicating a role for p-p38 in this process. Furthermore, p58(IPK) expression was increased in ERp29-overexpressing MDA-MB-231 cells and highly decreased in ERp29-knockdown MCF-7 cells. This upregulation of p58(IPK) by ERp29 suppresses the activation of p-p38/p-PERK/p-eIF2α by repressing eIF2α phosphorylation. In fact, reduction of p58(IPK) expression by RNA interference stimulated eIF2α phosphorylation. The repression of eIF2α phosphorylation by p58(IPK) prevents ERp29-transfected cells from undergoing ER-dependent apoptosis driven by the activation of ATF4/CHOP/caspase-3. Hence, the interplay between p38 phosphorylation and p58(IPK) upregulation has key roles in modulating ERp29-induced cell-growth arrest and survival.

Expression of the Chlamydomonas reinhardtii sedoheptulose-1,7-bisphosphatase in Dunaliella bardawil leads to enhanced photosynthesis and increased glycerol production.

Bioengineering of photoautotrophic microalgae into CO(2) scrubbers and producers of value-added metabolites is an appealing approach in low-carbon economy. A strategy for microalgal bioengineering is to enhance the photosynthetic carbon assimilation through genetically modifying the photosynthetic pathways. The halotolerant microalgae Dunaliella possess a unique osmoregulatory mechanism, which accumulates intracellular glycerol in response to extracellular hyperosmotic stresses. In our study, the Calvin cycle enzyme sedoheptulose 1,7-bisphosphatase from Chlamydomonas reinhardtii (CrSBPase) was transformed into Dunaliella bardawil, and the transformant CrSBP showed improved photosynthetic performance along with increased total organic carbon content and the osmoticum glycerol production. The results demonstrate that the potential of photosynthetic microalgae as CO(2) removers could be enhanced through modifying the photosynthetic carbon reduction cycle, with glycerol as the carbon sink.