The four effective antagonistic Bacillus strains, isolated from the rhizosphere soil of cucumber in a greenhouse, produced antifungal volatiles. These volatiles strongly inhibited the growth of the most tested pathoge...The four effective antagonistic Bacillus strains, isolated from the rhizosphere soil of cucumber in a greenhouse, produced antifungal volatiles. These volatiles strongly inhibited the growth of the most tested pathogenic fungi with wide host plants, induced the mycelial morphological abnormalities, and decreased the sclerotoid production of Sclerotinia sclerotiorum in sealed plates. Spores of Botrytis cinerea exposed to these volatiles for 24-48 h in cavity slides cracked and the sporaceous inclusion became brown and effused to the suspension. An interesting phenomenon observed was that all the bacterial volatiles exhibited intense inhibitory activities against the pigment formation of tested pathogenic fungi, including Ascochyta citrullina, Alternaria solani, Alternaria brassicae, and so on. Interactions mediated by microbial volatiles could be widespread in soils, and volatiles may play an important role in reducing disease levels. A phylogenetic analysis based on 16S rDNA sequence placed the four bacteria in three species Paenibacillus polymyxa （BMP-11）, Bacillus subtilis （BL02）, and Bacillus pumilus （BSH-4 and ZB 13）. Through headspace sampling and GC-MS analysis, a rich profile was found from B. subtilis and overlapping volatile patterns could be found among the different species. Studies are under the way to find the possible action mechanisms and to seek the effective application of bacterial volatiles in greenhouse.展开更多
Two indigenous microorganisms, Bacillus sp. SB02 and Mucor sp. SF06, capable of degrading polycyclic aromatic hydrocarbons （PAHs） were co-immobilized on vermiculite by physical adsorption and used to degrade benzo[a...Two indigenous microorganisms, Bacillus sp. SB02 and Mucor sp. SF06, capable of degrading polycyclic aromatic hydrocarbons （PAHs） were co-immobilized on vermiculite by physical adsorption and used to degrade benzo[a] pyrene （BaP）. The characteristics of BaP degradation by both free and co-immobilized microorganism were then investigated and compared. The removal rate using the immobilized bacterial-fungal mixed consortium was higher than that of the freely mobile mixed consortium. 95.3% of BaP was degraded using the co-immobilized system within 42 d, which was remarkably higher than the removal rate of that by the free strains. The optimal amount of inoculated co-immobilized system for BaP degradation was 2%. The immobilized bacterial-fungal mixed consortium also showed better water stability than the free strains. Kinetics of BaP biodegradation by co-immobilized SF06 and SB02 were also studied. The results demonstrated that BaP degradation could be well described by a zero-order reaction rate equation when the initial BaP concentration was in the range of 10--200 mg/kg. The scanning electronic microscope （SEM） analysis showed that the co-immobilized microstructure was suitable for the growth of SF06 and SB02. The mass transmission process of co-immobilized system in soil is discussed. The results demonstrate the potential for employing the bacterial-fungal mixed consortium, co-immobilized on vermiculite, for in situ bioremediation of BaP.展开更多
A pilot survey on a microbial mineral exploration method based on so il Bacillus cereus spore counts was carried out across three different gold mi ning regions, which vary in soil type, climate condition and geologi...A pilot survey on a microbial mineral exploration method based on so il Bacillus cereus spore counts was carried out across three different gold mi ning regions, which vary in soil type, climate condition and geological setting in northwestern Sichuan, China. B horizon soils from these sites were analyzed for B. cereus spores, Au, Ag, Cu, Pb and Zn. The results show that the numbe rs of B. cereus spores generally increased in soils overlying gold mineraliz ation. Specifically, elevated spore counts were found in samples slightly offset from the outcrops of orebodies, whereas soils directly above the outcrops of or ebodies usually contained low spore counts. However, the background counts of B. cereus spores varied from place to place and were complicated by environmen tal and pedological factors, but the relative ratios of spore counts still were indicative of the underlying gold mineralization.展开更多
Bacillus thuringiensis Bt185 and its insecticidal spectrum-expanded engineering strains are considered as potential biocontrol agents to soil insect Holotrichia parallela,Holotrichia oblita or Anomala corpulenta.Here ...Bacillus thuringiensis Bt185 and its insecticidal spectrum-expanded engineering strains are considered as potential biocontrol agents to soil insect Holotrichia parallela,Holotrichia oblita or Anomala corpulenta.Here we reported the complete genome of strain Bt185,it harbors eight plasmids,and plasmid p BT1850294 carries three cry8 genes.展开更多
Background:Previous research has shown that dietary supplementation of Bacillus spp.probiotics exerts beneficial effects on animals’growth.However,limited studies have evaluated the efficacy of Bacillus spp.on weaned...Background:Previous research has shown that dietary supplementation of Bacillus spp.probiotics exerts beneficial effects on animals’growth.However,limited studies have evaluated the efficacy of Bacillus spp.on weaned pigs and their effects on host gut health and microbiome,and systemic immunity using a disease challenge model.The objective of this experiment was to investigate the effects of two Bacillus spp.strains(Bacillus subtilis DSM 32540 and Bacillus pumilus DSM 32539)on growth performance,diarrhea,intestinal health,microbiome,and systemic immunity of weaned pigs experimentally infected with an enterotoxigenic Escherichia coli(ETEC).Results:Pigs in PRO1(Bacillus subtilis DSM 32540)had greater(P<0.05)body weight on d 7 and 14 PI,greater(P<0.05)ADG from d 0 to 7 and d 7 to 14 PI,compared with pigs in CON(Control).Pigs in PRO1 had milder(P<0.05)diarrhea on d 2 and 3 PI compared with pigs in CON.However,no differences were observed in growth performance and diarrhea score between PRO2(Bacillus pumilus DSM 32539)and CON groups.Supplementation of PRO1 decreased(P<0.05)lymphocyte counts on d 7 and 14 PI,compared with CON.Supplementation of PRO1 and PRO2 both reduced(P<0.05)total coliforms in mesenteric lymph nodes on d 21 PI.Pigs in PRO2 had greater(P<0.05)goblet cell number and sulfomucin percentage in duodenal villi and greater(P<0.05)sialomucin percentage in jejunal villi than pigs in CON.Supplementation of PRO1 up-regulated(P<0.05)MUC2 gene expression in jejunal mucosa and reduced(P<0.05)PTGS-2 and IL1B gene expression in ileal mucosa on d 21 PI,compared with CON.Pigs in PRO1 had reduced(P<0.05)relative abundance of families Lachnospiraceae,Peptostreptococcaceae and Pasteurellaceae in the ileum.Conclusions:Supplementation of Bacillus subtilis DSM 32540 improved growth performance,alleviated diarrhea severity,enhanced gut health,and reduced systemic inflammation of weaned pigs infected with ETEC F18.Although Bacillus pumilus DSM 32539 was able to alleviate systemic inflammation,it had limited impacts on growth performance and severity of diarrhea of ETEC F18 challenged weaned pigs.展开更多
Endophytes are hypothesized to be transferred across the soil-plant continuum, suggesting both the transfers of endophytes from environment to plant and from plant to soil. To verify this hypothesis and to assess the ...Endophytes are hypothesized to be transferred across the soil-plant continuum, suggesting both the transfers of endophytes from environment to plant and from plant to soil. To verify this hypothesis and to assess the role of locality, we evaluated the similarity of microbial communities commonly found both in soils and endophytic communities in three arid regions, i.e. the Jornada LTER （Long Term Ecological Research） site in New Mexico, USA, and the research station of Jordan University of Science and Technology （JUST） and Khanasd research station in Badia region of Jordan. Rhizosphere and non-rhizosphere soils, leaves and seeds of Atriplex spp. were sampled. Diversity and distribution of bacteria and fungi across the soil-plant continuums were assessed by tag-encoded FLX amplicon pyrosequencing and sequence alignment. Of the total bacterial OTUs （operational taxonomic units）, 0.17% in Khanasri research station, 0.16% in research station of JUST, and 0.42% in Jornada LTER site were commonly found across all the plant and soil compartments. The same was true for fungi in two regions, i.e. 1.56% in research station of JUST and 0.86% in Jornada LTER site. However, in Khanasri research station, 12.08% of total fungi OTUs were found in at least one soil compartment and one plant compartment. Putative Arthrobacter, Sporosarcina, Cladosporium and members of Proteobacteria and Actinobacteria were found across all the soil-plant continuums. Ascomycota, mainly including Didymellaceae, Pleosporaceae and Davidiellaceae were present across all the soil-plant continuums. Microbial communities in two regions of Jordan were similar to each other, but both of them were different from the Jornada LTER site of USA. SIMPER （similarity percentage） analysis of bacterial and fungal taxa for both soil and endophyte communities revealed that dissimilarities of two bacterial genera （Arthrobacter and Sporosarcina） and two fungal genera （Cladosporium and Alternaria） are very high, so they play key roles in the soil-plant continuums. A weighed Pearson correlation analysis for the specific bacterial OTUs in the soil-plant continuums only showed high similarity between the two regions of Jordan. However, fungal groups showed higher similarities among all regions. This research supports the hypothesis of continuity of certain bacterial and fungal communities across the soil-plant continuums, and also explores the influences of plant species and geographic specificity on diversity and distribution of bacteria and fungi.展开更多
Four isolates of Bacillus subtilis coded,B4,B7,B8 and B10 were examined as biocontrol agents for their abilities and antagonistic effect on the in vitro growth of certain phytopathogenic fungi of peanut,Rhizoctonia so...Four isolates of Bacillus subtilis coded,B4,B7,B8 and B10 were examined as biocontrol agents for their abilities and antagonistic effect on the in vitro growth of certain phytopathogenic fungi of peanut,Rhizoctonia solani and Sclerotium rolfsii.Bacillus subtilis isolate B4(GenBank accession no.EF150884)was the highly effective one for inhibiting the fungal mycelial growth.Batch fermentation of B.subtilis isolate B4 was carried out and the maximum biomass achieved was 4.53 g L-1 at 11 h.Bacillus subtilis isolate B4 was formulated and evaluated as a biofungicide to reduce peanut soil-borne diseases under greenhouse and field conditions at the side of Rizolex-T(fungicide)as standard.Treatments by formulated plant growth-promoting rhizobacteria(PGPR)B.subtilis B4 and Rizolex-T in a soil infested with R.solani,S.rolfsii and mixture of them were more effective in decreasing percentage of damping-off,root and pod rot disease incidence(%)in greenhouse and open field environment during the two seasons 2015 and 2016.Treatments by PGPR gave highly dry weight and number of healthy pods compared to control of fungi treatment which was nearby to dry weights of healthy pods achieved by treatments by Rizolex-T in a soil infested with S.rolfsii,R.solani and mixture of them.Formulated PGPR B.subtilis B4 gave higher increasing of yield percentage than treatment by Rizolex-T in the two evaluated seasons 2015 and 2016.It can conclude that the produced bioforumlated agent was more efficient as fungicide when compared with the other chemical synthesized fungicides,safe for human and the environment and economy.展开更多
[ Objective] The paper was to screen the antagonistic Bacillus spp. strains against Phytophthora infestans （Mont.） de Bary and analyze its lipepeptide substances. [ Methods] Using flat isolation and culture method, ...[ Objective] The paper was to screen the antagonistic Bacillus spp. strains against Phytophthora infestans （Mont.） de Bary and analyze its lipepeptide substances. [ Methods] Using flat isolation and culture method, the bacteria that could produce Bacillus spp. were isolated from rhizosphere soil, and carried out primary and secondary screening by confrontation culture. The lipopeptide substances of Y-3 strain with better antifungal effect were carried out I-IPLC analysis. [Result] Nine strains of bacteria had certain antagonistic effects against P. infestans in primary screening, Y-1 and Y-3 strains had significant inhibition effect against the growth of P. infestans in secondary screening, with inhibition rate higher than 80% ; the crude extract of lipepeptide produced by Y-3 strain had better antagonistic effect against P. infestans, with inhibition rate higher than 90%. HPLC analysis showed that the crude extract of lipepeptide mainly contained 8 components. [ Conclusion] The lipopeptide substances produced by Y-3 strain had significant inhibition effect, which had potential application value for biological control of potato late blight.展开更多
In order to improve the spore yield of compound Bacillus spp. (B. amyloliquefaciens, B. laterosporus and B. megaterium), the effects of nutrient conditions including carbon source, nitrogen source, mineral salt and fe...In order to improve the spore yield of compound Bacillus spp. (B. amyloliquefaciens, B. laterosporus and B. megaterium), the effects of nutrient conditions including carbon source, nitrogen source, mineral salt and fermentation conditions including the inoculum age, inoculation amount, loading volume of liquid and initial pH on the spore yield were studied. The results indicated that the optimized medium was glucoses 20 g/L, soybean meal 30.0 g/L, K2HPO4 1.0 g/L;fermentation temperature is 37℃, the inoculum age 12 h, initial pH 7.0, 2% inoculation amount, loading volume of liquid 20 mL/250 mL. Under the optimized conditions of culture medium and fermentation for compound Bacillus spp., spore yield was 10.24 times more than the initial medium, and the spore formation rate reached more than 90%.展开更多
Introduction: Bacillus cereus and spores produced in various ecological niches are responsible for toxic infections in humans. This study is conducted to determine the antibiotics resistance profile of B. cereus strai...Introduction: Bacillus cereus and spores produced in various ecological niches are responsible for toxic infections in humans. This study is conducted to determine the antibiotics resistance profile of B. cereus strains isolated from soil and pepper consummated in Brazzaville. Methodology: An antimicrobial susceptibility test of 16 B. cereus strains from soil and peppers was performed using 11 antibiotics by the Kirby-Bauer’s diffusion on disc method. Results: Results revealed 100% (16/16) of resistance in penicillin G, amoxicillin, ceftazidime, rifampicin, and colistin, also 18.75% (3/16), 11.76% (2/16), and 18.75% (3/16) of resistance in doripenem, vancomycin and chloramphenicol respectively. In addition, we have observed 100% (16/16), 81.25% (13/16), 76.47% (13/16), 35.29% (5/16), 35.50% (6/16), and 12.5% (2/16) of sensitivity to line-zolid, tigecycline, ciprofloxacin, vancomycin, doripenem and chloram-phenicol respectively. However, all strains have been multidrug resistant (MDR) to betalactams, polypeptides, and ansamycins. Moreover, 7 strains (43.75%) have been variably multiresistant. One strain, Ri10 has been resistant to beta-lactams, polypeptides, ansamycins, cyclins and glycopeptides. No strain was ultraresistant (XDR) or largely insensitive (PDR) to different antibiotics. Conclusion: This study reveals that 51% of strains have been resistant to antibiotics, 32% are sensitive, and 17% have intermediate resistance. These results partly explain the high rate of gastroenteritis observed in Brazzaville due to food poisoning.展开更多
The present study was taken up with a view to ascertain the possibility of introduction of alcohol resistant bacteria in vitro through the aseptically raised watermelon (Citrullus lanatus) seedlings in the backdrop of...The present study was taken up with a view to ascertain the possibility of introduction of alcohol resistant bacteria in vitro through the aseptically raised watermelon (Citrullus lanatus) seedlings in the backdrop of isolating such organisms from micropropagated watermelon stocks. Watermelon cv. Arka Manik seedlings grown in vitro from surface-sterilized seeds with the intact seed coat on MS medium appeared visibly clean largely, but upon subjecting them to tissue-indexing, the segments from the collar or root tissue showed bacterial colony growth on Nutrient Agar (NA) from 72% of such healthy seedlings and the cotyledon and hypocotyl tissue of 44% seedlings. The pooled colony growth from NA upon challenge with 90% alcohol yielded 10 distinct colony types, identified as B. pumilus (4×), B. subtilis (4×), B. cereus (1×) or B. safensis (1×) based on partial 16S rRNA sequence analysis. The shoot-tip tissue from the healthy index-negative seedlings cultured on watermelon proliferation medium partly turned index-positive within 2 - 4 sub-culture cycles while being apparently clean. On the other hand, those from the previously index-positive cultures tended to show obvious bacterial growth during subsequent in vitro culturing. The observations suggested the possibility of introduction of spore-forming Bacillus spp. through surface-sterilized seeds, their gradual emergence in vitro in visibly clean seedlings, possible transmittal of spores to the alcohol through tissue-culturing tools and the survival therein with the chances of unsuspected lateral spread. Seed coat removal followed by surface sterilization with sodium hypochlorite facilitated the raising of clean seedlings with no detectable bacterial association.展开更多
基金the National Key Technology R&D Program of China (2006BAD08A03)the Shandong Agricultural University Postdoctoral Foundation (200603065)
文摘The four effective antagonistic Bacillus strains, isolated from the rhizosphere soil of cucumber in a greenhouse, produced antifungal volatiles. These volatiles strongly inhibited the growth of the most tested pathogenic fungi with wide host plants, induced the mycelial morphological abnormalities, and decreased the sclerotoid production of Sclerotinia sclerotiorum in sealed plates. Spores of Botrytis cinerea exposed to these volatiles for 24-48 h in cavity slides cracked and the sporaceous inclusion became brown and effused to the suspension. An interesting phenomenon observed was that all the bacterial volatiles exhibited intense inhibitory activities against the pigment formation of tested pathogenic fungi, including Ascochyta citrullina, Alternaria solani, Alternaria brassicae, and so on. Interactions mediated by microbial volatiles could be widespread in soils, and volatiles may play an important role in reducing disease levels. A phylogenetic analysis based on 16S rDNA sequence placed the four bacteria in three species Paenibacillus polymyxa （BMP-11）, Bacillus subtilis （BL02）, and Bacillus pumilus （BSH-4 and ZB 13）. Through headspace sampling and GC-MS analysis, a rich profile was found from B. subtilis and overlapping volatile patterns could be found among the different species. Studies are under the way to find the possible action mechanisms and to seek the effective application of bacterial volatiles in greenhouse.
基金The National Basic Research Program (973) of China (No. 2004CB418506)the National Natural Science Foundation of China (No.20337010) the Hi-Tech Research and Development Program (863) of China (No. 2004AA649060)
文摘Two indigenous microorganisms, Bacillus sp. SB02 and Mucor sp. SF06, capable of degrading polycyclic aromatic hydrocarbons （PAHs） were co-immobilized on vermiculite by physical adsorption and used to degrade benzo[a] pyrene （BaP）. The characteristics of BaP degradation by both free and co-immobilized microorganism were then investigated and compared. The removal rate using the immobilized bacterial-fungal mixed consortium was higher than that of the freely mobile mixed consortium. 95.3% of BaP was degraded using the co-immobilized system within 42 d, which was remarkably higher than the removal rate of that by the free strains. The optimal amount of inoculated co-immobilized system for BaP degradation was 2%. The immobilized bacterial-fungal mixed consortium also showed better water stability than the free strains. Kinetics of BaP biodegradation by co-immobilized SF06 and SB02 were also studied. The results demonstrated that BaP degradation could be well described by a zero-order reaction rate equation when the initial BaP concentration was in the range of 10--200 mg/kg. The scanning electronic microscope （SEM） analysis showed that the co-immobilized microstructure was suitable for the growth of SF06 and SB02. The mass transmission process of co-immobilized system in soil is discussed. The results demonstrate the potential for employing the bacterial-fungal mixed consortium, co-immobilized on vermiculite, for in situ bioremediation of BaP.
文摘A pilot survey on a microbial mineral exploration method based on so il Bacillus cereus spore counts was carried out across three different gold mi ning regions, which vary in soil type, climate condition and geological setting in northwestern Sichuan, China. B horizon soils from these sites were analyzed for B. cereus spores, Au, Ag, Cu, Pb and Zn. The results show that the numbe rs of B. cereus spores generally increased in soils overlying gold mineraliz ation. Specifically, elevated spore counts were found in samples slightly offset from the outcrops of orebodies, whereas soils directly above the outcrops of or ebodies usually contained low spore counts. However, the background counts of B. cereus spores varied from place to place and were complicated by environmen tal and pedological factors, but the relative ratios of spore counts still were indicative of the underlying gold mineralization.
基金supported by the National Natural Science Foundation of China (31301731, 31428020)the National Science and Technology Major Project (2014ZX08009013B)
文摘Bacillus thuringiensis Bt185 and its insecticidal spectrum-expanded engineering strains are considered as potential biocontrol agents to soil insect Holotrichia parallela,Holotrichia oblita or Anomala corpulenta.Here we reported the complete genome of strain Bt185,it harbors eight plasmids,and plasmid p BT1850294 carries three cry8 genes.
基金supported by Evonik Nutrition&Care GmbH,Germany and the United States Department of Agriculture(USDA)National Institute of Food and Agriculture,multistate project W400。
文摘Background:Previous research has shown that dietary supplementation of Bacillus spp.probiotics exerts beneficial effects on animals’growth.However,limited studies have evaluated the efficacy of Bacillus spp.on weaned pigs and their effects on host gut health and microbiome,and systemic immunity using a disease challenge model.The objective of this experiment was to investigate the effects of two Bacillus spp.strains(Bacillus subtilis DSM 32540 and Bacillus pumilus DSM 32539)on growth performance,diarrhea,intestinal health,microbiome,and systemic immunity of weaned pigs experimentally infected with an enterotoxigenic Escherichia coli(ETEC).Results:Pigs in PRO1(Bacillus subtilis DSM 32540)had greater(P<0.05)body weight on d 7 and 14 PI,greater(P<0.05)ADG from d 0 to 7 and d 7 to 14 PI,compared with pigs in CON(Control).Pigs in PRO1 had milder(P<0.05)diarrhea on d 2 and 3 PI compared with pigs in CON.However,no differences were observed in growth performance and diarrhea score between PRO2(Bacillus pumilus DSM 32539)and CON groups.Supplementation of PRO1 decreased(P<0.05)lymphocyte counts on d 7 and 14 PI,compared with CON.Supplementation of PRO1 and PRO2 both reduced(P<0.05)total coliforms in mesenteric lymph nodes on d 21 PI.Pigs in PRO2 had greater(P<0.05)goblet cell number and sulfomucin percentage in duodenal villi and greater(P<0.05)sialomucin percentage in jejunal villi than pigs in CON.Supplementation of PRO1 up-regulated(P<0.05)MUC2 gene expression in jejunal mucosa and reduced(P<0.05)PTGS-2 and IL1B gene expression in ileal mucosa on d 21 PI,compared with CON.Pigs in PRO1 had reduced(P<0.05)relative abundance of families Lachnospiraceae,Peptostreptococcaceae and Pasteurellaceae in the ileum.Conclusions:Supplementation of Bacillus subtilis DSM 32540 improved growth performance,alleviated diarrhea severity,enhanced gut health,and reduced systemic inflammation of weaned pigs infected with ETEC F18.Although Bacillus pumilus DSM 32539 was able to alleviate systemic inflammation,it had limited impacts on growth performance and severity of diarrhea of ETEC F18 challenged weaned pigs.
文摘Endophytes are hypothesized to be transferred across the soil-plant continuum, suggesting both the transfers of endophytes from environment to plant and from plant to soil. To verify this hypothesis and to assess the role of locality, we evaluated the similarity of microbial communities commonly found both in soils and endophytic communities in three arid regions, i.e. the Jornada LTER （Long Term Ecological Research） site in New Mexico, USA, and the research station of Jordan University of Science and Technology （JUST） and Khanasd research station in Badia region of Jordan. Rhizosphere and non-rhizosphere soils, leaves and seeds of Atriplex spp. were sampled. Diversity and distribution of bacteria and fungi across the soil-plant continuums were assessed by tag-encoded FLX amplicon pyrosequencing and sequence alignment. Of the total bacterial OTUs （operational taxonomic units）, 0.17% in Khanasri research station, 0.16% in research station of JUST, and 0.42% in Jornada LTER site were commonly found across all the plant and soil compartments. The same was true for fungi in two regions, i.e. 1.56% in research station of JUST and 0.86% in Jornada LTER site. However, in Khanasri research station, 12.08% of total fungi OTUs were found in at least one soil compartment and one plant compartment. Putative Arthrobacter, Sporosarcina, Cladosporium and members of Proteobacteria and Actinobacteria were found across all the soil-plant continuums. Ascomycota, mainly including Didymellaceae, Pleosporaceae and Davidiellaceae were present across all the soil-plant continuums. Microbial communities in two regions of Jordan were similar to each other, but both of them were different from the Jornada LTER site of USA. SIMPER （similarity percentage） analysis of bacterial and fungal taxa for both soil and endophyte communities revealed that dissimilarities of two bacterial genera （Arthrobacter and Sporosarcina） and two fungal genera （Cladosporium and Alternaria） are very high, so they play key roles in the soil-plant continuums. A weighed Pearson correlation analysis for the specific bacterial OTUs in the soil-plant continuums only showed high similarity between the two regions of Jordan. However, fungal groups showed higher similarities among all regions. This research supports the hypothesis of continuity of certain bacterial and fungal communities across the soil-plant continuums, and also explores the influences of plant species and geographic specificity on diversity and distribution of bacteria and fungi.
文摘Four isolates of Bacillus subtilis coded,B4,B7,B8 and B10 were examined as biocontrol agents for their abilities and antagonistic effect on the in vitro growth of certain phytopathogenic fungi of peanut,Rhizoctonia solani and Sclerotium rolfsii.Bacillus subtilis isolate B4(GenBank accession no.EF150884)was the highly effective one for inhibiting the fungal mycelial growth.Batch fermentation of B.subtilis isolate B4 was carried out and the maximum biomass achieved was 4.53 g L-1 at 11 h.Bacillus subtilis isolate B4 was formulated and evaluated as a biofungicide to reduce peanut soil-borne diseases under greenhouse and field conditions at the side of Rizolex-T(fungicide)as standard.Treatments by formulated plant growth-promoting rhizobacteria(PGPR)B.subtilis B4 and Rizolex-T in a soil infested with R.solani,S.rolfsii and mixture of them were more effective in decreasing percentage of damping-off,root and pod rot disease incidence(%)in greenhouse and open field environment during the two seasons 2015 and 2016.Treatments by PGPR gave highly dry weight and number of healthy pods compared to control of fungi treatment which was nearby to dry weights of healthy pods achieved by treatments by Rizolex-T in a soil infested with S.rolfsii,R.solani and mixture of them.Formulated PGPR B.subtilis B4 gave higher increasing of yield percentage than treatment by Rizolex-T in the two evaluated seasons 2015 and 2016.It can conclude that the produced bioforumlated agent was more efficient as fungicide when compared with the other chemical synthesized fungicides,safe for human and the environment and economy.
基金Supported by Natural Science Foundation of Hebei Province( C2011201003)
文摘[ Objective] The paper was to screen the antagonistic Bacillus spp. strains against Phytophthora infestans （Mont.） de Bary and analyze its lipepeptide substances. [ Methods] Using flat isolation and culture method, the bacteria that could produce Bacillus spp. were isolated from rhizosphere soil, and carried out primary and secondary screening by confrontation culture. The lipopeptide substances of Y-3 strain with better antifungal effect were carried out I-IPLC analysis. [Result] Nine strains of bacteria had certain antagonistic effects against P. infestans in primary screening, Y-1 and Y-3 strains had significant inhibition effect against the growth of P. infestans in secondary screening, with inhibition rate higher than 80% ; the crude extract of lipepeptide produced by Y-3 strain had better antagonistic effect against P. infestans, with inhibition rate higher than 90%. HPLC analysis showed that the crude extract of lipepeptide mainly contained 8 components. [ Conclusion] The lipopeptide substances produced by Y-3 strain had significant inhibition effect, which had potential application value for biological control of potato late blight.
文摘In order to improve the spore yield of compound Bacillus spp. (B. amyloliquefaciens, B. laterosporus and B. megaterium), the effects of nutrient conditions including carbon source, nitrogen source, mineral salt and fermentation conditions including the inoculum age, inoculation amount, loading volume of liquid and initial pH on the spore yield were studied. The results indicated that the optimized medium was glucoses 20 g/L, soybean meal 30.0 g/L, K2HPO4 1.0 g/L;fermentation temperature is 37℃, the inoculum age 12 h, initial pH 7.0, 2% inoculation amount, loading volume of liquid 20 mL/250 mL. Under the optimized conditions of culture medium and fermentation for compound Bacillus spp., spore yield was 10.24 times more than the initial medium, and the spore formation rate reached more than 90%.
文摘Introduction: Bacillus cereus and spores produced in various ecological niches are responsible for toxic infections in humans. This study is conducted to determine the antibiotics resistance profile of B. cereus strains isolated from soil and pepper consummated in Brazzaville. Methodology: An antimicrobial susceptibility test of 16 B. cereus strains from soil and peppers was performed using 11 antibiotics by the Kirby-Bauer’s diffusion on disc method. Results: Results revealed 100% (16/16) of resistance in penicillin G, amoxicillin, ceftazidime, rifampicin, and colistin, also 18.75% (3/16), 11.76% (2/16), and 18.75% (3/16) of resistance in doripenem, vancomycin and chloramphenicol respectively. In addition, we have observed 100% (16/16), 81.25% (13/16), 76.47% (13/16), 35.29% (5/16), 35.50% (6/16), and 12.5% (2/16) of sensitivity to line-zolid, tigecycline, ciprofloxacin, vancomycin, doripenem and chloram-phenicol respectively. However, all strains have been multidrug resistant (MDR) to betalactams, polypeptides, and ansamycins. Moreover, 7 strains (43.75%) have been variably multiresistant. One strain, Ri10 has been resistant to beta-lactams, polypeptides, ansamycins, cyclins and glycopeptides. No strain was ultraresistant (XDR) or largely insensitive (PDR) to different antibiotics. Conclusion: This study reveals that 51% of strains have been resistant to antibiotics, 32% are sensitive, and 17% have intermediate resistance. These results partly explain the high rate of gastroenteritis observed in Brazzaville due to food poisoning.
文摘The present study was taken up with a view to ascertain the possibility of introduction of alcohol resistant bacteria in vitro through the aseptically raised watermelon (Citrullus lanatus) seedlings in the backdrop of isolating such organisms from micropropagated watermelon stocks. Watermelon cv. Arka Manik seedlings grown in vitro from surface-sterilized seeds with the intact seed coat on MS medium appeared visibly clean largely, but upon subjecting them to tissue-indexing, the segments from the collar or root tissue showed bacterial colony growth on Nutrient Agar (NA) from 72% of such healthy seedlings and the cotyledon and hypocotyl tissue of 44% seedlings. The pooled colony growth from NA upon challenge with 90% alcohol yielded 10 distinct colony types, identified as B. pumilus (4×), B. subtilis (4×), B. cereus (1×) or B. safensis (1×) based on partial 16S rRNA sequence analysis. The shoot-tip tissue from the healthy index-negative seedlings cultured on watermelon proliferation medium partly turned index-positive within 2 - 4 sub-culture cycles while being apparently clean. On the other hand, those from the previously index-positive cultures tended to show obvious bacterial growth during subsequent in vitro culturing. The observations suggested the possibility of introduction of spore-forming Bacillus spp. through surface-sterilized seeds, their gradual emergence in vitro in visibly clean seedlings, possible transmittal of spores to the alcohol through tissue-culturing tools and the survival therein with the chances of unsuspected lateral spread. Seed coat removal followed by surface sterilization with sodium hypochlorite facilitated the raising of clean seedlings with no detectable bacterial association.
