Prodigiosin: unveiling the crimson wonder – a comprehensive journey from diverse bioactivity to synthesis and yield enhancement

Prodigiosin (PG) is a red tripyrrole pigment from the prodiginine family that has attracted widespread attention due to its excellent biological activities, including anticancer, antibacterial and anti-algal activities. The synthesis and production of PG is of particular significance, as it has the potential to be utilized in a number of applications, including those pertaining to clinical drug development, food safety, and environmental management. This paper provides a systematic review of recent research on PG, covering aspects like chemical structure, bioactivity, biosynthesis, gene composition and regulation, and optimization of production conditions, with a particular focus on the biosynthesis and regulation of PG in Serratia marcescens. This provides a solid theoretical basis for the drug development and production of PG, and is expected to promote the further development of PG in medicine and other applications

Genes Associated with 2-Methylisoborneol Biosynthesis in Cyanobacteria: Isolation, Characterization, and Expression in Response to Light

The volatile microbial metabolite 2-methylisoborneol (2-MIB) is a root cause of taste and odor issues in freshwater. Although current evidence suggests that 2-MIB is not toxic, this compound degrades water quality and presents problems for water treatment. To address these issues, cyanobacteria and actinomycetes, the major producers of 2-MIB, have been investigated extensively. In this study, two 2-MIB producing strains, coded as Pseudanabaena sp. and Planktothricoids raciborskii, were used in order to elucidate the genetic background, light regulation, and biochemical mechanisms of 2-MIB biosynthesis in cyanobacteria. Genome walking and PCR methods revealed that two adjacent genes, SAM-dependent methyltransferanse gene and monoterpene cyclase gene, are responsible for GPP methylation and subsequent cyclization to 2-MIB in cyanobacteria. These two genes are located in between two homologous cyclic nucleotide-binding protein genes that may be members of the Crp-Fnr regulator family. Together, this sequence of genes forms a putative operon. The synthesis of 2-MIB is similar in cyanobacteria and actinomycetes. Comparison of the gene arrangement and functional sites between cyanobacteria and other organisms revealed that gene recombination and gene transfer probably occurred during the evolution of 2-MIB-associated genes. All the microorganisms examined have a common origin of 2-MIB biosynthesis capacity, but cyanobacteria represent a unique evolutionary lineage. Gene expression analysis suggested that light is a crucial, but not the only, active regulatory factor for the transcription of 2-MIB synthesis genes. This light-regulated process is immediate and transient. This study is the first to identify the genetic background and evolution of 2-MIB biosynthesis in cyanobacteria, thus enhancing current knowledge on 2-MIB contamination of freshwater

Phylogenetic relationships and genetic divergence of paralytic shellfish toxin- and cylindrospermopsin- producing Cylindrospermopsis and raphidiopsis

Cylindrospermopsis and Raphidiopsis (C/R group) are closely related species responsible for cyanobacterial blooms worldwide. Paralytic shellfish toxins (PSTs) and cylindrospermopsins (CYNs) have been identified in different C/R group strains. However, the evolutionary relationship between PST- and CYN-producing strains has not been systematically evaluated. In this study, C/R group strains and their toxin biosynthesis genes were evaluated by phylogenetic analysis and sequence comparison. None of the tested strains are able to produce PSTs and CYNs simultaneously. The C/R group strains were clustered into five clades, including two non-toxic, two CYN-producing and one PST-producing clades. A high degree of similarity was observed for rpoC1 (> 96%) and ITS-L (> 97%) sequences within each clade with the exception of the ITS-L (87% to 100%) region in CYN-producing R. curvata, which has been shown to contain variable sequence insertions. Genomic analysis revealed that sxtY and sxtZ could be found in both toxic and non-toxic strains. The transposase gene IS4 was only observed in strains from the PST-producing clade. The sxt and cyr gene clusters share five gene families with similar functions. The amino acid sequences of the adenylyl-sulfate kinase genes, sxtO and cyrN, are more similar (45% to 81%) than other pairs of genes (8.0% to 40%). SxtO and CyrN proteins from C/R group strains forms an independent clade on the phylogenetic tree with a high degree of sequence similarity (78% to 100%). In conclusion, PST- and CYN-producing C/R group species can be classified into different clades based on their phylogenetic profile. The sxtO and cyrN genes have probably diverged from a single ancestral adenylyl-sulfate kinase gene, and may be specifically used for toxin biosynthesis in C/R group species

Genotypes of ITS region of rRNA in Microcystis (Cyanobacteria) populations in Erhai Lake (China) and their correlation with eutrophication level

Previous studies on spatiotemporal changes of Microcystis genotypes have shown that the existence and succession of dominant genotypes always occur in eutrophicated freshwater bodies. However, few studies have focused on the correlation between genotype composition and eutrophication level. In the present study, clone libraries of the internal transcribed spacer (ITS) of rrn operon were sequenced from Microcystis populations in Erhai Lake, a subtropical plateau lake in the preliminary eutrophication stage. The genotype composition of the Microcystis populations was highly variable at spatiotemporal scales, and 473 ITS genotypes were identified from the 800 ITS sequences obtained. However, no significantly dominant ITS genotypes existed in the lake. Comparison of Erhai Lake with four major lakes in China, namely, Taihu, Chaohu, Gucheng, and Shijiu Lakes, showed that the Microcystis ITS genotypes and genetic diversity were negatively correlated with eutrophication level. Extensive comparison of the Microcystis ITS genotypes from waters worldwide revealed that 440 ITS genotypes were unique to Erhai Lake, and no obvious phylogenetic correlations can be detected among the dominant genotypes from different water bodies. The high genetic diversity of the Microcystis populations in Erhai Lake may have resulted from the effect of the early stage of eutrophication

Revealing Cryptic Changes of Cyanobacterial Community Structure in Two Eutrophic Lakes Using eDNA Sequencing

Harmful cyanobacterial blooms pose a risk to human health worldwide. To enhance understanding on the bloom-forming mechanism, the spatiotemporal changes in cyanobacterial diversity and composition in two eutrophic lakes (Erhai Lake and Lushui Reservoir) of China were investigated from 2010 to 2011 by high-throughput sequencing of environmental DNA. For each sample, 118 to 260cpcBA-IGS operational taxonomic units (OTUs) were obtained. Fifty-two abundant OTUs were identified, which made up 95.2% of the total sequences and were clustered into nine cyanobacterial groups. Although the cyanobacterial communities of both lakes were mainly dominated byMicrocystis, Erhai Lake had a higher cyanobacterial diversity. The abundance of mixed Nostocales species was lower than that ofMicrocystis, whereasPhormidiumandSynechococcuswere opportunistically dominant. The correlation between the occurrence frequency and relative abundance of OTUs was poorly fitted by the Sloan neutral model. Deterministic processes such as phosphorus availability were shown to have significant effects on the cyanobacterial community structure in Erhai Lake. In summary, theMicrocystis-dominated cyanobacterial community was mainly affected by the deterministic process. Opportunistically dominant species have the potential to replaceMicrocystisand form blooms in eutrophic lakes, indicating the necessity to monitor these species for drinking water safety

Targeted deep sequencing reveals high diversity and variable dominance of bloom-forming cyanobacteria in eutrophic lakes

Cyanobacterial blooms in eutrophic lakes are severe environmental problems worldwide. To characterize the spatiotemporal heterogeneity of cyanobacterial blooms, a high-throughput method is necessary for the specific detection of cyanobacteria. In this study, the cyanobacterial composition of three eutrophic waters in China (Taihu Lake, Dongqian Lake, and Dongzhen Reservoir) was determined by pyrosequencing the cpcBA intergenic spacer (cpcBA-IGS) of cyanobacteria. A total of 2585 OTUs were obtained from the normalized cpcBA-IGS sequence dataset at a distance of 0.05. The 238 most abundant OTUs contained 92% of the total sequences and were classified into six cyanobacterial groups. The water samples of Taihu Lake were dominated by Microcystis, mixed Nostocales species, Synechococcus, and unclassified cyanobacteria. Besides, all the samples from Taihu Lake were clustered together in the dendrograrn based on shared abundant OTUs. The cyanobacterial diversity in Dongqian Lake was dramatically decreased after sediment dredging and Synechococcus became exclusively dominant in this lake. The genus Synechococcus was also dominant in the surface water of Dongzhen Reservoir, while phylogenetically diverse cyanobacteria coexisted at a depth of 10 m in this reservoir. In summary, targeted deep sequencing based on cpcBA-IGS revealed a large diversity of bloom-forming cyanobacteria in eutrophic lakes and spatiotemporal changes in the composition of cyanobacterial communities. The genus Microcystis was the most abundant bloom-forming cyanobacteria in eutrophic lakes, while Synechococcus could be exclusively dominant under appropriate environmental conditions. (C) 2017 Elsevier B.V. All rights reserved

Parkin enhances sensitivity of paclitaxel to nasopharyngeal carcinoma by activating BNIP3/NIX-mediated mitochondrial autophagy

As a malignant head and neck cancer, nasopharyngeal carcinoma (NPC) has high morbidity. Parkin expression has been reported to be reduced in NPC tissues and its upregulation could enhance paclitaxel-resistant cell cycle arrest. This study was performed to explore the possible mechanism of Parkin related to B-cell lymphoma-2 (Bcl-2)/adenovirus E1B 19 kDa interacting protein 3 (BNIP3)/BNIP3-like (NIX)-mediated mitochondrial autophagy in NPC cells. Initially, after Parkin overexpression or silencing, cell viability and proliferation were evaluated by lactate dehydrogenase and colony formation assays. JC-1 staining was used to assess the mitochondrial membrane potential. In addition, the levels of cellular reactive oxygen species (ROS) and mitochondrial ROS were detected using DCFH-DA staining and mitochondrial ROS (MitoSOX) red staining. The expression of proteins was measured using Western blot. Results showed that Parkin overexpression inhibited, whereas Parkin knockdown promoted the proliferation of paclitaxel-treated NPC cells. Besides, Parkin overexpression induced, whereas Parkin knockdown inhibited mitochondrial apoptosis in paclitaxel-treated NPC cells, as evidenced by the changes of Cytochrome C (mitochondria), Cytochrome C (cytoplasm), BAK, and Bcl-2 expression. Moreover, the levels of ROS, mitochondrial membrane potential, and LC3II/LC3I in paclitaxel-treated C666-1 cells were hugely elevated by Parkin overexpression and were all declined by Parkin knockdown in CNE-3 cells. Furthermore, Parkin upregulation activated, whereas Parkin downregulation inactivated BNIP3/NIX signaling. Further, BNIP3 silencing or overexpression reversed the impacts of Parkin upregulation or downregulation on the proliferation and mitochondrial apoptosis of paclitaxel-treated NPC cells. Particularly, Mdivi-1 (mitophagy inhibitor) or rapamycin (an activator of autophagy) exerted the same effects on NPC cells as BNIP3 silencing or overexpression, respectively. Collectively, Parkin overexpression activated BNIP3/NIX-mediated mitochondrial autophagy to enhance sensitivity to paclitaxel in NPC

Recent Advances in the Ecology of Bloom-Forming Raphidiopsis (Cylindrospermopsis) raciborskii: Expansion in China, Intraspecific Heterogeneity and Critical Factors for Invasion

Water blooms caused by the invasive cyanobacterium Raphidiopsis raciborskii occur in many reservoirs in the tropical and subtropical regions of China. In recent decades, this species has spread rapidly to temperate regions. Phenotypic plasticity and climate warming are thought to promote the worldwide dispersion of R. raciborskii. However, investigations into the genetic and phenotypic diversities of this species have revealed significant intraspecific heterogeneity. In particular, competition between R. raciborskii and Microcystis aeruginosa was highly strain dependent. Although the concept of an ecotype was proposed to explain the heterogeneity of R. raciborskii strains with different geographic origins, microevolution is more reasonable for understanding the coexistence of different phenotypes and genotypes in the same environment. It has been suggested that intraspecific heterogeneity derived from microevolution is a strong driving force for the expansion of R. raciborskii. Additionally, temperature, nutrient fluctuations, and grazer disturbance are critical environmental factors that affect the population establishment of R. raciborskii in new environments. The present review provides new insights into the ecological mechanisms underlying the invasion of R. raciborskii in Chinese freshwater ecosystems