Intermediate-mass black holes in Green pea galaxies(IMBH-GP)I:A candidate sample from LAMOST and SDSS

The scaling relation of central massive black holes(M_(BH)s)and their host galaxies is well-studied for supermassive BHs(SM_(BH)s,M_(BH)≥10^(6)M_(⊙)).However,this relation has large uncertainties in the mass range of the intermediate-mass BHs(IM_(BH)s,M_(BH)~10^(3)-10^(6)M_(⊙)).Since Green pea(GP)galaxies are luminous compact dwarf galaxies,which may be likely to host less massive SM_(BH)s or even IM_(BH)s,we systematically search for M_(BH)s in a large sample of 2190 GP galaxies at z<0.4,selected from LAMOST and SDSS spectroscopic surveys.Here,we report a newly discovered sample of 59 M_(BH) candidates with broad Hαlines.This sample has a median stellar mass of 108.83±0.11M_(⊙)and hosts M_(BH)s with single-epoch virial masses ranging from M_(BH)~10^(4.7)to 10^(8.5)M_(⊙)(median 105.85±0.64M_(⊙)).Among the 59 M_(BH) candidates,36 have black hole masses M_(BH)≤10^(6)M_(⊙)(IM_(BH) candidates),one of which even has M_(BH)■10^(5)M_(⊙).We find that the M_(BH)-M_(*)relation of our M_(BH) sample is consistent with the M_(BH)-M_(bulge)relation for SM_(BH)s,while is above the M_(BH)-M_(*)relation for M_(BH)s in dwarf galaxies in the same mass range.Furthermore,we show that 25 M_(BH) candidates,including 4 IM_(BH) candidates,have additional evidence of black hole activities,assessed through various methods such as the broad-line width,BPT diagram,mid-infrared color,X-ray luminosity,and radio emission.Our studies show that it is very promising to find IM_(BH)s in GP galaxies,and the BH sample so obtained enables us to probe the connection between the M_(BH)s and compact dwarf galaxies in the low-redshift Universe.

Response of Salmonella enterica serovar Typhimurium to alginate oligosaccharides fermented with fecal inoculum:integrated transcriptomic and metabolomic analyses

Alginate oligosaccharides(AOS),extracted from marine brown algae,are a common functional feed additive;however,it remains unclear whether they modulate the gut microbiota and microbial metabolites.The response of Salmonella enterica serovar Typhimurium,a common poultry pathogen,to AOS fermented with chicken fecal inocula was investigated using metabolomic and transcriptomic analyses.Single-strain cultivation tests showed that AOS did not directly inhibit the growth of S.Typhimurium.However,when AOS were fermented by chicken fecal microbiota,the supernatant of fermented AOS(F-AOS)exhibited remarkable antibacterial activity against S.Typhimurium,decreasing the abundance ratio of S.Typhimurium in the fecal microbiota from 18.94 to 2.94%.Transcriptomic analyses showed that the 855 diferentially expressed genes induced by F-AOS were mainly enriched in porphyrin and chlorophyll metabolism,oxidative phosphorylation,and Salmonella infection-related pathways.RT-qPCR confrmed that F-AOS downregulated key genes involved in fagellar assembly and the type III secretory system of S.Typhimurium,indicating metabolites in F-AOS can infuence the growth and metabolism of S.Typhimurium.Metabolomic analyses showed that 205 microbial metabolites were signifcantly altered in F-AOS.Among them,the increase in indolelactic acid and 3-indolepropionic acid levels were further confrmed using HPLC.This study provides a new perspective for the application of AOS as a feed additive against pathogenic intestinal bacteria.

Bacteriostatic effect of lipopeptides from Bacillus subtilis N-2 on Pseudomonas putida using soybean meal by solid-state fermentation

Bacillus subtilis N-2 which was isolated from natto,produced lipopeptides using soybean meal as a substrate.This work aimed to purify,identify,and determine the antibacterial mechanism of lipopeptides produced by B.subtilis N-2.The fermented product obtained by solid-state fermentation was subjected to water extraction,acid precipitation,and methanol extraction.Fractions were separated and collected using a two-step ultrafiltration method and then identified by LC-MS/MS.Mass spectrometry characterization revealed the presence of four variants of iturin A that differed according to the p-amino fatty acid chain from C14 to C17 as well as the amino acid positions.A new lipopeptide(m/z 1070.3)was identified and its structure was different from the previously reported lipopeptides.The lipopeptides were shown to inhibit the growth of an isolate of Pseudomonas putida,a common pathogen in decaying fish,by changing membrane permeability.These results suggest that the lipopeptides from B.subtilis N-2 could be used as a biocontrol agent in aquaculture.

Eco-friendly preparation of chitooligosaccharides with different degrees of deacetylation from shrimp shell waste and their effects on the germination of wheat seeds

Production of chitosan and its derivatives by traditional methods involves the excessive use of a reaction solution comprisedof sodium hydroxide and hydrochloric acid. Waste water resulting from this process has lim让ed the application of chitosanas a fertilizer as the process causes serious environmental pollution. Specifically, the resulting waste water contains highlevels of dissolved nitrogen and minerals from shrimp shells. In this study, an eco-friendly method was established to produce chitooligosaccharides (COS) with different degrees of deacetylation (DDAs) from shrimp shell waste. At a solid-tosolventratio of 1:6, the degree of demineralization was above 90% with the treatment of 30 g-L_1 H3PO4, and the degree ofdeproteinization was above 80% when treated with 30 g-L_1 KOH at 70 °C. Chitosans with different DDAs were obtainedby microwave-assisted KOH metathesis and the COS with Mw approximately 1500 Da were then prepared by oxidativedegradation. In summary, 33.73 kg H3PO4,12.77 kg, and 241.31 kg KOH were supplied during the processes of demineralization,deproteinization, and deacetylation of 100 kg shrimp shell waste, respectively. The process water was totally recycled,demonstrating that the shrimp shell could be wholly transformed into fertilize The entire process created a product withthe fractions of N:P2O5:K2O:COS = 7.94:24.44:10.72:1 &27. The test on the germination promotion of wheat seeds revealedthat the COS with 72」2% DDA significantly promoted germination. This work demonstrated the use of an eco-friendlypreparation method of COS with a specific degree of deacetylation that can be applied as a fertilizer.