Pretreatment of Low-Density Polyethylene(LDPE)with physicochemical methods before biodegradation has been demonstrated as an effective strategy.The pretreatment of LDPE exhibited alterations in molecular structure,red...Pretreatment of Low-Density Polyethylene(LDPE)with physicochemical methods before biodegradation has been demonstrated as an effective strategy.The pretreatment of LDPE exhibited alterations in molecular structure,reducing hydrophobicity and decreasing tensile strength.Additionally,pretreating LDPE enhanced microbial biodegradability to improve biofilm formation and significantly reduced the physical weight of LDPE film.AS3–8 consortia exhibited a maximum weight loss of 8.0%±0.5%after 45 days of incubation.While Bacillus sp.AS3 and Sphingobacterium sp.AS8 demonstrated LDPE weight loss of 5.03%±1.6%and 1.6%±0.5%,respectively.The structure of LDPE was altered after incubation with the bacterial strains,resulting in a reduction in the intensity of functional groups,including C=O,C=C,N–H,and C–N.The carbonyl index(CI)of LDPE also decreased by 7.17%after the consortia AS3–8 degradation.Consortia AS3–8 significantly impacted the physical properties of LDPE by reducing the water contact angle(WCA),decreasing to 64.21°±3.69°,and tensile strength(TS),decreasing to 17.97±0.3 MPa.Moreover,the esterase activity was measured through 45 days of incubation.SDS-PAGE analysis of the AS3–8 consortia revealed bands at 35,48,and 70 kDa molecular weights,similar to known enzymes like laccase and esterase.Furthermore,SEM observations showed rough,cracked surfaces on pretreated LDPE,with biofilms present after incubation with the bacterial strains.GC–MS analysis revealed that AS3–8 consortia produced depolymerized chemicals,including alkanes,aldehydes,and esters.The LDPE biodegradation pathway was elucidated.This study addresses critical knowledge gaps in improving plastic degradation efficiency.展开更多
Three new free-living marine nematodes belong to the order Enoplida from the Yellow Sea,China are described.The first new species,Halanonchus gracilis sp.nov.is characterized by inner labial sensilla papillose,outer l...Three new free-living marine nematodes belong to the order Enoplida from the Yellow Sea,China are described.The first new species,Halanonchus gracilis sp.nov.is characterized by inner labial sensilla papillose,outer labial setae and cephalic setae thick,with thin tips;oval amphideal fovea located posterior to buccal cavity;males possessing midventral row of 10-12 papilliform pharyngeal supplements and 13-15 unequal papilliform precloacal supplements;spicules almost straight,0.85-1.0 cloacal body diameter long;gubernaculum rod-shaped.The main difference between the described species and other known species within the genus is that precloacal supplements are unequal,6-7 posterior supplements smaller and closer,the rest 7-8 proximal supplements larger and far away.The genus Halanonchus is the first record from the Chinese sea area.The second new species,Micoletzkyia oxycephalata sp.nov.is characterized by very sharp-pointed anterior part of body,paired spicules unequal and precloacal supplement situated anterior to proximal end of spicules.This new species can be easily distinguished from all other known species of Micoletzkyia by outstanding body shape,unequal spicules,stick shaped gubernaculum without apophysis,and the position of precloacal supplement.The third new species,Wieseria zhangi sp.nov.is characterized by slender body with a clavate tail;large amphideal fovea oblong,double contour with a manubrium basally,situated posterior to cephalic setae;spicules short,slightly arcuated,not cephalated proximally,without internal stripe and ventral alae;gubernaculum rodlike,without apophysis;a short midventral spine positioned 11-12μm anterior to the cloaca.Updated keys to species of three genera Halanonchus,Micoletzkyia,and Wieseria are also given.展开更多
Microorganisms capable of solubilizing and mineralizing phosphorus （P） pools in soils are considered vital in promoting P bioavallability. The study was conducted to screen and isolate inorganic P-solubilizing bacte...Microorganisms capable of solubilizing and mineralizing phosphorus （P） pools in soils are considered vital in promoting P bioavallability. The study was conducted to screen and isolate inorganic P-solubilizing bacteria （IPSB） and organic P-mineralizing bacteria （OPMB） in soils taken from subtropical flooded and temperate non-flooded soils, and to compare inorganic P-solubilizing and organic P-solubilizing abilities between IPSB and OPMB. Ten OPMB strains were isolated and identified as Bacillus cereus and Bacillus megaterium, and five IPSB strains as B. megaterium, Burkholderia caryophyUi, Pseudomonas cichorii, and Pseudomonas syringae. P-solubilizing and -mineralizing abilities of the strains were measured using the methods taking cellular P into account. The IPSB strains exhibited inorganic P-solubilizing abilities ranging between 25.4-41.7 μg P mL^-1 and organic P-mineralizing abilities between 8.2-17.8μg P mL^-1. Each of the OPMB strains also exhibited both solubilizing and mineralizing abilities varying from 4.4 to 26.5 μg P mL^-1 and from 13.8 to 62.8 μg P mL^-1, respectively. For both IPSB and OPMB strains, most of the P mineralized from the organic P source was incorporated into the bacterial cells as cellular P. A significantly negative linear correlation （P 〈 0.05） was found between culture pH and P solubilized from inorganic P by OPMB strains. The results suggested that P solubilization and mineralization could coexist in the same bacterial strain.展开更多
文摘Pretreatment of Low-Density Polyethylene(LDPE)with physicochemical methods before biodegradation has been demonstrated as an effective strategy.The pretreatment of LDPE exhibited alterations in molecular structure,reducing hydrophobicity and decreasing tensile strength.Additionally,pretreating LDPE enhanced microbial biodegradability to improve biofilm formation and significantly reduced the physical weight of LDPE film.AS3–8 consortia exhibited a maximum weight loss of 8.0%±0.5%after 45 days of incubation.While Bacillus sp.AS3 and Sphingobacterium sp.AS8 demonstrated LDPE weight loss of 5.03%±1.6%and 1.6%±0.5%,respectively.The structure of LDPE was altered after incubation with the bacterial strains,resulting in a reduction in the intensity of functional groups,including C=O,C=C,N–H,and C–N.The carbonyl index(CI)of LDPE also decreased by 7.17%after the consortia AS3–8 degradation.Consortia AS3–8 significantly impacted the physical properties of LDPE by reducing the water contact angle(WCA),decreasing to 64.21°±3.69°,and tensile strength(TS),decreasing to 17.97±0.3 MPa.Moreover,the esterase activity was measured through 45 days of incubation.SDS-PAGE analysis of the AS3–8 consortia revealed bands at 35,48,and 70 kDa molecular weights,similar to known enzymes like laccase and esterase.Furthermore,SEM observations showed rough,cracked surfaces on pretreated LDPE,with biofilms present after incubation with the bacterial strains.GC–MS analysis revealed that AS3–8 consortia produced depolymerized chemicals,including alkanes,aldehydes,and esters.The LDPE biodegradation pathway was elucidated.This study addresses critical knowledge gaps in improving plastic degradation efficiency.
基金Supported by the National Natural Science Foundation of China(No.41676146)。
文摘Three new free-living marine nematodes belong to the order Enoplida from the Yellow Sea,China are described.The first new species,Halanonchus gracilis sp.nov.is characterized by inner labial sensilla papillose,outer labial setae and cephalic setae thick,with thin tips;oval amphideal fovea located posterior to buccal cavity;males possessing midventral row of 10-12 papilliform pharyngeal supplements and 13-15 unequal papilliform precloacal supplements;spicules almost straight,0.85-1.0 cloacal body diameter long;gubernaculum rod-shaped.The main difference between the described species and other known species within the genus is that precloacal supplements are unequal,6-7 posterior supplements smaller and closer,the rest 7-8 proximal supplements larger and far away.The genus Halanonchus is the first record from the Chinese sea area.The second new species,Micoletzkyia oxycephalata sp.nov.is characterized by very sharp-pointed anterior part of body,paired spicules unequal and precloacal supplement situated anterior to proximal end of spicules.This new species can be easily distinguished from all other known species of Micoletzkyia by outstanding body shape,unequal spicules,stick shaped gubernaculum without apophysis,and the position of precloacal supplement.The third new species,Wieseria zhangi sp.nov.is characterized by slender body with a clavate tail;large amphideal fovea oblong,double contour with a manubrium basally,situated posterior to cephalic setae;spicules short,slightly arcuated,not cephalated proximally,without internal stripe and ventral alae;gubernaculum rodlike,without apophysis;a short midventral spine positioned 11-12μm anterior to the cloaca.Updated keys to species of three genera Halanonchus,Micoletzkyia,and Wieseria are also given.
基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars, the Ministry of Education of the P.R. China.
文摘Microorganisms capable of solubilizing and mineralizing phosphorus （P） pools in soils are considered vital in promoting P bioavallability. The study was conducted to screen and isolate inorganic P-solubilizing bacteria （IPSB） and organic P-mineralizing bacteria （OPMB） in soils taken from subtropical flooded and temperate non-flooded soils, and to compare inorganic P-solubilizing and organic P-solubilizing abilities between IPSB and OPMB. Ten OPMB strains were isolated and identified as Bacillus cereus and Bacillus megaterium, and five IPSB strains as B. megaterium, Burkholderia caryophyUi, Pseudomonas cichorii, and Pseudomonas syringae. P-solubilizing and -mineralizing abilities of the strains were measured using the methods taking cellular P into account. The IPSB strains exhibited inorganic P-solubilizing abilities ranging between 25.4-41.7 μg P mL^-1 and organic P-mineralizing abilities between 8.2-17.8μg P mL^-1. Each of the OPMB strains also exhibited both solubilizing and mineralizing abilities varying from 4.4 to 26.5 μg P mL^-1 and from 13.8 to 62.8 μg P mL^-1, respectively. For both IPSB and OPMB strains, most of the P mineralized from the organic P source was incorporated into the bacterial cells as cellular P. A significantly negative linear correlation （P 〈 0.05） was found between culture pH and P solubilized from inorganic P by OPMB strains. The results suggested that P solubilization and mineralization could coexist in the same bacterial strain.
