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Cholesterol (CHOL) is one of the risk factors causing the blockage of the arterial wall, atherosclerosis, coronary heart disease, and other serious cardiovascular diseases. Here, a promising bacterial strain for biodegrading CHOL was successfully isolated from the gut of healthy individuals and identified as Enterococcus faecium YY01 with an analysis of the 16S rDNA sequence. An initial CHOL of 1.0 g/L was reduced to 0.5 g/L in 5 days, and glucose and beef extract were found to be optimal carbon and nitrogen sources for the rapid growth of YY01, respectively. To gain further insight into the mechanisms underlying CHOL biodegradation, the draft genome of YY01 was sequenced using Illumina HiSeq. Choloylglycine hydrolase, acyltransferase, and alkyl sulfatase was encoded by gene0586, gene1890, and gene2442, which play crucial roles in converting 3α, 7α, 12α-trihydroxy-5β-choranic acid to choline-CoA and then choline-CoA to bile acid. Notably, choloylglycine hydrolase was closely related to the biosynthesis of both primary and secondary bile acid. The findings of this study provide valuable insights into the metabolism pathway of CHOL biodegradation by YY01 and offer a potential avenue for the development of bacterioactive drugs against hypercholesterolemia. [ABSTRACT FROM AUTHOR]

Both inosine and guanosine are precursors of uric acid that may cause the diseases of hyperuricemia and gout in humans. Here, a promising bacterial strain for efficiently biodegrading both inosine and guanosine was successfully isolated from a healthy human intestine and identified as Bacillus paranthracis YD01 with 16S rRNA analysis. An initial amount of 49.6 mg·L−1 of inosine or 49.9 mg·L−1 of guanosine was completely removed by YD01 within 12 h, which showed that YD01 had a strong ability to biodegrade inosine and guanosine. Furthermore, the initial amount of 49.2 mg·L−1 of inosine or 49.5 mg·L−1 of guanosine was totally catalyzed by the intracellular crude enzymes of YD01 within 6 h, and the initial inosine amount of 49.6 mg·L−1 or guanosine of 49.7 mg·L−1 was biodegraded by the extracellular crude enzymes of YD01 within 9 h. Illumina Hiseq sequencing and database gene annotation were used to elucidate the genomic characteristics of B. paranthracis YD01. Purine nucleoside phosphorylase, encoded by gene 1785, gene 3933, and gene 4403, was found in the KEEG database, which played a crucial role in the biodegradation of inosine and guanosine. The results of this study provide valuable insights into the mechanisms for biodegrading inosine and guanosine using B. paranthracis YD01. [ABSTRACT FROM AUTHOR]

Gossypol, generally found in the roots, stems, leaves, and, especially, the seeds of cotton plants, is highly toxic to animals and humans, which inhibits the use of cotton stalks as a feed resource. Here, a promising fungal strain for biodegrading gossypol was successfully isolated from the soil of cotton stalk piles in Xinjiang Province, China, and identified as Aspergillus terreus-YJ01 with the analysis of ITS. Initial gossypol of 250 mg·L−1 could be removed by 97% within 96 h by YJ01, and initial gossypol of 150 mg·L−1 could also be catalyzed by 98% or 99% within 36 h by the intracellular or extracellular crude enzymes of YJ01. Sucrose and sodium nitrate were found to be the optimal carbon and nitrogen sources for the growth of YJ01, and the optimal initial pH and inoculum size for the growth of YJ01 were 6.0 and 1%, respectively. To further elucidate the mechanisms underlying gossypol biodegradation by YJ01, the draft genome of YJ01 was sequenced using Illumina HiSeq, which is 31,566,870 bp in length with a GC content of 52.27% and a total of 9737 genes. Eight genes and enzymes were predicted to be involved in gossypol biodegradation. Among them, phosphoglycerate kinase, citrate synthase, and other enzymes are related to the energy supply process. With sufficient energy, β-1, 4-endo-xylanase may achieve the purpose of biodegrading gossypol. The findings of this study provide valuable insights into both the basic research and the application of A. terreus-YJ01 in the biodegradation of gossypol in cotton stalks. [ABSTRACT FROM AUTHOR]

Hepatotoxic microcystins (MCs) are produced and released by the harmful bloom-forming cyanobacteria, which severely threaten drinking water safety and human health due to their high toxicity, widespread distribution, and structural stability. The linearized microcystinase (MlrB) further hydrolyses the poisonous linearized MCs produced by the microcystinase-catalysed MCs to form tetrapeptides. Here, the purification and activity of MlrB were investigated. The results showed that the linearized products generated by 12.5 mg/L MC-LR and MC-RR were removed by purified recombinant MlrB at a protein concentration of 1 mg/L within 30 min. The high catalytic activity of MlrB can be obtained via heterologous expression and affinity purification, which lays the foundation for further studies on the properties and mechanism of MCs biodegradation enzymes. [ABSTRACT FROM AUTHOR]

High serum uric acid levels, known as hyperuricemia (HUA), are associated with an increased risk of developing gout, chronic kidney disease, cardiovascular disease, diabetes, and other metabolic syndromes. In this study, a promising bacterial strain capable of biodegrading uric acid (UA) was successfully isolated from Baijiu cellar mud using UA as the sole carbon and energy source. The bacterial strain was identified as Bacillus paramycoides-YC02 through 16S rDNA sequence analysis. Under optimal culture conditions at an initial pH of 7.0 and 38 °C, YC02 completely biodegraded an initial UA concentration of 500 mg/L within 48 h. Furthermore, cell-free extracts of YC02 were found to catalyze and remove UA. These results demonstrate the strong biodegradation ability of YC02 toward UA. To gain further insight into the mechanisms underlying UA biodegradation by YC02, the draft genome of YC02 was sequenced using Illumina HiSeq. Subsequent analysis revealed the presence of gene1779 and gene2008, which encode for riboflavin kinase, flavin mononucleotide adenylyl transferase, and flavin adenine dinucleotide (FAD)-dependent urate hydroxylase. This annotation was based on GO or the KEEG database. These enzymes play a crucial role in the metabolism pathway, converting vitamin B2 to FAD and subsequently converting UA to 5-hydroxyisourate (HIU) with the assistance of FAD. Notably, HIU undergoes a slow non-enzymatic breakdown into 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline (OHCU) and (S)-allantoin. The findings of this study provide valuable insights into the metabolism pathway of UA biodegradation by B. paramycoides-YC02 and offer a potential avenue for the development of bacterioactive drugs against HUA and gout. [ABSTRACT FROM AUTHOR]

Cyanobacterial hepatotoxins, including microcystins (MCs) and nodularins (NODs), are widely produced, distributed and extremely hazardous to human beings and the environment. However, the catalytic mechanism of microcystinase for biodegrading cyanobacterial hepatotoxins is not completely understood yet. The first microcystinase (MlrA) catalyzes the ring opening of cyclic hepatotoxins, while being further hydrolyzed by the third microcystinase (MlrC). Based on the homology modeling, we postulated that MlrC of Sphingopyxis sp. USTB-05 was a Zn2+-dependent metalloprotease including five active sites: Glu56, His150, Asp184, His186 and His208. Here, the active recombinant MlrC and five site-directed mutants were successfully obtained with heterologous expression and then purified for investigating the activity. The results indicated that the purified recombinant MlrC had high activity to catalyze linearized hepatotoxins. Combined with the biodegradation of linearized NOD by MlrC and its mutants, a complete enzymatic mechanism for linearized hepatotoxin biodegradation by MlrC was revealed. [ABSTRACT FROM AUTHOR]

Sphingopyxis sp. USTB-05, which we previously identified and examined, is a well-known bacterial strain for biodegrading cyanobacterial hepatotoxins of both nodularins (NODs) and microcystins (MCs). Although the pathways for biodegrading the different types of [D-Asp1] NOD, MC-YR, MC-LR and MC-RR by Sphingopyxis sp. USTB-05 were suggested, and several biodegradation genes were successfully cloned and expressed, the comprehensive genomic analysis of Sphingopyxis sp. USTB-05 was not reported. Here, based on second and third generation sequencing technology, we analyzed the whole genome of Sphingopyxis sp. USTB-05, which is 4,679,489 bp and contains 4,312 protein coding genes. There are 88 protein-coding genes related to the NODs and MCs biodegradation, of which 16 genes (bioA, hmgL, hypdh, speE, nspC, phy, spuC, murD, glsA, ansA, ocd, crnA, ald, gdhA, murC and murI) are unique. These genes for the transformation of phenylacetic acid CoA (PA-CoA) to CO2 were also found in Sphingopyxis sp. USTB-05. This study expands the understanding of the pathway for complete biodegradation of cyanobacterial hepatotoxins by Sphingopyxis sp. USTB-05. [ABSTRACT FROM AUTHOR]