Unveiling the impact:COVID-19's influence on bacterial resistance in the Kingdom of Bahrain

BACKGROUND Antibiotic resistance is a growing global health threat,and understanding local trends in bacterial isolates and their susceptibility patterns is crucial for effective infection control and antimicrobial stewardship.The coronavirus disease 2019(COVID-19)pandemic has introduced additional complexities,potentially influencing these patterns.AIM To analyze trends in bacterial isolates and their antibiotic susceptibility patterns at Salmaniya Medical Complex from 2018 to 2023,with a specific focus on the impact of the COVID-19 pandemic on these trends.METHODS A retrospective analysis of microbiological data was conducted,covering the period from 2018 to 2023.The study included key bacterial pathogens such as Escherichia coli(E.coli),Klebsiella pneumoniae,Acinetobacter baumannii,Pseudomonas aeruginosa,and Staphylococcus aureus,among others.The antibiotic susceptibility profiles of these isolates were assessed using standard laboratory methods.To contextualize the findings,the findings were compared with similar studies from other regions,including China,India,Romania,Saudi Arabia,the United Arab Emirates,Malaysia,and United States.RESULTS The study revealed fluctuating trends in the prevalence of bacterial isolates,with notable changes during the COVID-19 pandemic.For example,a significant increase in the prevalence of Staphylococcus aureus was observed during the pandemic years,while the prevalence of E.coli showed a more variable pattern.Antibiotic resistance rates varied among the different pathogens,with a concerning rise in resistance to commonly used antibiotics,particularly among Klebsiella pneumoniae and E.coli.Additionally,the study identified an alarming increase in the prevalence of multidrug-resistant(MDR)strains,especially within Klebsiella pneumoniae and E.coli isolates.The impact of the COVID-19 pandemic on these trends was evident,with shifts in the frequency,resistance patterns,and the emergence of MDR bacteria among several key pathogens.CONCLUSION This study highlights the dynamic nature of bacterial isolates and their antibiotic susceptibility patterns at Salmaniya Medical Complex,particularly in the context of the COVID-19 pandemic.The findings underscore the need for continuous monitoring and effective anti-microbial stewardship programs to combat the evolving threat of antibiotic resistance.Further research and policy initiatives are required to address the identified challenges and improve patient outcomes in the face of these ongoing challenges.

Antimicrobial Susceptibility Patterns of the Bacterial Isolates in Post-Operative Wound Infections in a Tertiary Care Hospital, Kathmandu, Nepal

Unrestrained anti-microbial resistance (AMR) among bacterial pathogens has made the management and treatment of post-operative wound infections difficult. This study assessed the current AMR patterns of bacterial isolates in post-operative wound infections in a tertiary care hospital in Kathmandu,Nepal. Pus swabs collected from post-operative wound infections and submitted for culture and sensitivity were included in this study. Isolation and identification of the organism was done by standard microbiological methods. Antibiotic susceptibility test was performed by Kirby Bauer disc diffusion method and result was interpreted as per National Committee for Clinical Laboratory Standards (NCCLS) guide lines. Of the 120 pus swabs processed for culture, 96 showed bacterial growth. Staphylococcus aureus 36 (37.5%) was the predominant gram positive isolate and Escherichia coli 24 (25%) was the major gram negative isolate .The infection was most prevalent in the age group 20-40 years. All S. aureus isolates were sensitive to aminoglycosides and vancomycin. Out of 36 S. aureus, 15 (41.66%) isolates were methicillin resistant S. aureus (MRSA). Staphylococcus epidermidis showed high resistance (50%-100%) to all antibiotics but were sensitive to vancomycin. All gram negative isolates showed high resistance against cephalexin (75%-100%) and ceftriaxone (25%-100%). Overall multi-drug resistant isolates were 66.7%. A high level of AMR was observed in gram negative bacterial isolates. Rational use of antibiotics and a regular monitoring of AMR patterns in post-operative wound infections are essential and mandatory to avert further emergence and spread of anti-microbial resistance among bacterial pathogens.

A comparative study of bacterial isolates from the urine samples of AIDS and non-AIDS patients in Benue,Nigeria

Objective:To determine the common bacterial causes of urinary tract infection and their antibiotic susceptibility pattern in AIDS patients versus non-AIDS patients.Methods:One thousand consecutive AIDS patients with signs and symptoms of AIDS and non-AIDS patients (served as control) each on admission were recruited into the study between January 2005 to January 2008,in Federal Medical Center,Makurdi.Urine samples were collected with sterile universal bottles and analysed with appropriate laboratory methods and antibiotic susceptibility test was carried out by disk diffusion technique in accordance with National Committee for Clinical Laboratory Standards(NCCLS,now CLSI) criteria.The results were analysed using SPSS 11.0 statistical software.Results:Urine samples of AIDS patients with urinary infection had a more spectrum of micro-organisms including Candida organisms,Pseudomonas aeruginosa and Staphylococcus aureus.Ceftriaxone,Ceftazidime or Ciprofloxacin had a remarkably high anti-bacterial activity across the two study groups.A general resistance was recorded in ampicillin.tetracycline and co-trimoxazole.There was no significant difference in antibiotic susceptibility patterns between AIDS and non- AIDS patients(P】0.05).Conclusions:A reduction in unnecessary use of antibiotics as well as infection control should be encouraged in our health facilities.

Growth Responses of Some Bacterial Isolates to Some Environmental Parameters

This study was carried out to investigate the antimicrobial activities of bacterial isolates of maize against plant pathogens as well as their growth responses to some environmental parameters. Twenty four bacterial isolates were obtained from maize plants collected from the Department of Biological Sciences, AfeBabalola University, Ado-Ekiti. The isolates were characterized by their biochemical and physiological characteristics and were identified as Kurthiazopfu, Morganellamorganic, Rhodococcusequi, Bacillus subtilis, Catabaterhongkongensis, Brevibacteriumotitidis, Lactobacillus coleohominis, Staphylococcus aureus, Propionibacterium acnes among others. Their responses to different NaCl concentrations, sugars, temperature as well as antibiotics were determined. Most of the isolates were able to withstand various environmental parameters in which they were subjected to. Also, eight isolates were able to ferment sucrose. The bacterial isolates showed a degree of resistance to the antibiotics tested. There was a high prevalence of multidrug resistant bacteria showing resistance to 3 - 8 drugs. The antagonistic effect of the bacterial isolates against selected fungi was determined. None of the isolates showed antagonistic potential against the fungal pathogens. However, the supposed antagonistic bacterial species can be genetically modified to produce secondary metabolites that will result in biocontrol.

Isolation and Characterization of Nickel Uptake by Nickel Resistant Bacterial Isolate (NiRBI)

Objective Bioremediation technology has gained importance because microbes could be the convenient source of bio-absorption/bioaccumulation of metals from effluent streams. Methods The nickel-resistant bacterial isolates （NiRBI） were selected from various bacterial isolates from industrial effluent and grown in nutrient broth containing different concentrations of nickel sulfate （0.3-3.0 mmol/L） and their capability of accumulating metal from the medium. Results Well-defined growth of NiRBI was observed in the medium containing up to 2.5 mmol/L of nickel. The isolate was identified using 16S rRNA and closely related to Pseudomonas fragi. Maximum accumulation of nickel （0.59 mg/g dry weight of bacterial cells） was observed when NiRBI was grown in media containing 2 mmol/L of nickel. The protein profile of the NiRBI cellular extract by SDS-PAGE showed two metal stress-induced proteins of molecular weight 48 KD and 18 KD with a simultaneous down regulation of four proteins of 46.7 KD, 42.2 KD, 19.7 KD, and 4.0 KD. Conclusion 48 KD and 18 KD proteins play a role in metal resistance mechanism by NiRBI.

Antibacterial activity of plant methanolic extracts on a field isolate of <i>Pseudomonas syringae</i>pvtomato from the Casablanca region (Morocco)

A bacterial field isolate recovered from infected tomato plants in a green-house at Sidi Rehal, a region near Casablanca city (Morocco), was identified as the gammaproteobacterium Pseudomonas syringae pv. tomato DC3000 strain, the causal agent of bacterial speck. The bacterial isolate was characterized by morphological, biochemical and molecular biological tests, its growth curves carried out in various culture media, and its phytopathogenicity verified by infection tests. A screening was performed to evaluate the antibacterial activity of methanolic extracts of 12 selected Moroccan plants against the P. syringae pv. tomato DC3000 isolate, and Agar-well diffusion and Broth microdilution methods were used to determine minimum inhibitory and minimum bactericidal concentrations. Among the methanolic extracts tested, only those of Nigella sativa, Geranuim robertianum, Aizoon canariense and Rubia peregrine showed clear inhibitory and bactericidal activities, although the highest values were achieved with N. sativa, a plant used in Morocco as a spice, condiment and medicinal treatment.

External Bacterial Flora and Antimicrobial Susceptibility Patterns of Staphylococcus spp. and Pseudomonas spp. Isolated from Two Household Cockroaches, Blattella germanica and Blatta orientalis

A study was performed to estimate the prevalence of the external bacterial flora of two domestic cockroaches （Blattella germanica and Blatta orientalis） collected from households in Tebessa （northeast AIgeria）.Three major bacterial groups were cultured （total aerobic, enterobacteria, and staphylococci） from 14 specimens of cockroaches, and antibiotic susceptibility was tested for both Staphylococcus and Pseudomonas isolates. Culturing showed that the total bacterial load of cockroaches from different households were comparable （P〈0.001） and enterobacteria were the predominant colonizers of the insect surface, with a bacterial load of （2.1×10^5 CFU/insect）, whereas the staphylococci group was the minority. Twenty-eight bacterial species were isolated, and susceptibility patterns showed that most of the staphylococci isolates were highly susceptible to chloramphenicol, gentamycin, pristinamycin, ofloxacin, clindamycin, and vancomycin; however, Pseudomonas strains exhibited resistance to amoxicillin/clavulanic acid, imipenem, and the second-generation antibiotic cephalosporin cefuroxime.

Isolation, Identification and Pathogenicity Evaluation of Pathogens of Soybean Bacterial Diseases

In order to research soybean bacterial diseases in Heilongiiang Province, a bacterial strain was isolated from diseased leaves of Suinong 14 collected from Harbin Yanjiagang farm. The pathogen had been carried out antibiotic resistance identification, molecular identification, re-inoculation identification and pathogenicity identification respectively. By Gram staining, pathogen inoculation test, 16S rDNA molecular identification, the pathogen was determined as Pseudomonas syringae and named Psgneau 2. The isolated strain presented resistance to 25, 50 and 100 μg/mL ampicillin and carbenicillin, but susceptible to spectinomycin, rifampicin, kanamycin, gentamicin, tetracycline and chloramphenicol. Ten soybean varieties were inoculated with Psgneau 2, in which Suinong 14 was more susceptible than other varieties and Hefeng 35 presented higher resistance to Psgneau 2.

Antibiotic sensitivity pattern of bacterial pathogens in the intensive care unit of Fatmawati Hospital,Indonesia

Objective:To evaluate the sensitivity pattern of bacterial pathogens in the intensive care unit(ICU) of a tertiary care of Falmawati Hospital Jakarta Indonesia.Methods:A cross sectional retrospective study of bacterial pathogen was carried out on a total of 722 patients that were admitted to the ICU of Fatmawati Hospital Jakarta Indonesia during January 2009 to March 2010. All bacteria were identified by standard microbiologic methods,and(heir antibiotic susceptibility testing was performed using disk diffusion method.Results:Specimens were collected from 385 patients who were given antimicrobial treatment,of which 249(64.68%) were cultured positive and 136(35.32%) were negative.The most predominant isolate was Pseudomonas aeruginosa(P.aeruginosa)(26.5%) followed by Klebsiella pneumoniae(K.pneumoniae)(15.3%) and Staphylococcus epidermidis(14.9%).P.aeruginosa isolates showed high rate of resistance to cephalexin(95.3%),cefotaxime(64.1%),and ceftriaxone(60.9%).Amikacin was the most effective(84.4%) antibiotic against P.aeruginosa followed by imipenem(81.2%),and meropenem(75.0%).K.pneumoniae showed resistance to cephalexin(86.5%),ceftriaxone(75.7%),ceftazidime(73.0%),cefpirome(73.0%) and cefotaxime(67.9%),respectively.Conclusions:Most bacteria isolated from ICU of Fatmawati Hospital Jakarta Indonesia were resistant to the third generation of cephalosporins,and quinolone antibiotics.Regular surveillance of antibiotic susceptibility pallerns is very important for setting orders to guide the clinician in choosing empirical or directed therapy of infected patients.

Antibacterial activity of Lawsonia inermis Linn(Henna) against Pseudomonas aeruginosa

Objective:To investigate the antibacterial activity of henna(Lawsonia inermis Linn) obtained from different regions of Oman against a wide array of micro-organisms.Methods:fresh henna samples were obtained from different regions of Oman as leaves and seeds,100 g fresh and dry leaves and SO g of fresh and dry seeds were separately soaked in 500 mL of ethanol for three days,respectively,with frequent agitation.The mixture was filtered,and the crude extract was collected.The crude extract was then heated,at 48 ℃ in a water bath to evaporate its liquid content.The dry crude henna extract was then tested for its antibacterial activity using well-diffusion antibiotic susceptibility technique.Henna extracts were investigated for their antibacterial activity at different concentrations against a wide array of different micro-organisms including a laboratory standard bacterial strain of Pseudomonas aeruginosa(NCTC 10662)(A aeruginosa) and eleven fresh clinical isolates of P.aeruginosa obtained from patients attending the Sultan Qaboos University Hospital(SQUH).2-Hydroxy-p-Nathoqinone-Tech(2-HPNT, MW=174.16,C_(10)H_40_3) was included as control(at 50%concentration) along with the henna samples tested.Results:Henna samples demonstrated antibacterial activity against all isolates but the highest susceptibility was against P.aeruginosa with henna samples obtained from Al-sharqyia region.Conclusions:Omani henna from Al-sharqyia region demonstrates high in vitro anti-P. aeruginosa activity compared with many henna samples from different regions of Oman.

Evaluation of the new OxyPlate^(TM) Anaerobic System for the isolation of ocular anaerobic bacteria

AIM: Anaerobic bacteria can cause ocular infections. We tested the OxyPlateTM Anaerobic System (OXY) to isolate pertinent anaerobic bacteria that can cause ocular disease.METHODS: OXY, which does not require direct anaerobic conditions (i.e. bags, jars), was compared to conventional isolation of incubating culture media in anaerobic bags. Standard colonies counts were performed on anaerobic ocular bacterial isolates under aerobic and anaerobic conditions (anaerobic bags) using agar media: 1) OXY (aerobic only), 2) 5% sheep blood (SB), 3) Chocolate, and 4) Schaedler. The bacteria tested were de-identified ocular isolates cultured from endophthalmitis and dacryocystitis that include 10 Propionibacterium acnes and 3 Actinomyces species. The colony counts for each bacteria isolate, on each culturing condition, were ranked from largest to smallest, and non-parametrically compared to determine the best culturing condition.RESULTS: All anaerobic conditions were positive for all of the anaerobic isolates. SB and Schaedler’s agar under aerobic conditions did not support the growth of anaerobic bacteria. Sparse growth was noted on chocolate agar with Propionibacterium acnes . As an anaerobic system, SB in an anaerobic bag isolated higher colony counts than OXY (P=0.0028) and chocolate agar (P=0.0028).CONCLUSION: Although OXY did not test to be more efficient than other anaerobic systems, it appears to be a reasonable alternative for isolating anaerobic bacteria from ocular sites. The use of an agar medium in a specially designed plate, without the requirement of an anaerobic bag, rendered OXY as an advantage over other anaerobic systems.

Ultrastable graphene isolated Au Ag nanoalloy for SERS biosensing and photothermal therapy of bacterial infection

Plasmonic metal nanomaterials with intrinsic surface–enhanced Raman scattering(SERS)and photothermal properties,especially AuAg nanoalloys with both the outstanding merits of Au and Ag nanocrystals,show huge application prospects in bacterial theranostics.However,the direct exposure of AuAg nanoalloys in external conditions probably cause undesirable reactions and poisonous metal ion leakage during SERS detection and photothermal antibacterial therapy process,which severely hinder bacterial theranostics applications.Herein,we report an ultrastable graphene–isolated AuAg nanoalloy(GAA)with AuAg core confined in few–layer graphitic shell as a versatile platform for bacterial detection and therapy.The encapsulation of graphene ensures the good stability of AuAg core,that its superior SERS and photothermal properties are therefore further guaranteed.GAA is used for SERS detection of two vital bacterial biomarkers(including corrosive cyanide and pyocyanin),exhibiting good SERS quantitative and multiplexing ability.GAA is further used for photothermal antibacterial therapy application,and ultrahigh antibacterial efficacies for both Gram–negative Escherichia coli and Gram–positive Staphylococcus aureus are achieved under 808 nm laser irradiation.This work proposes a valuable method to develop robust bacterial theranostic platform.

Isolation and Identification of Burkholderia glumae from Symptomless Rice Seeds

A survey on isolation and detection of the casual organism of bacterial grain rot of rice was conducted during 1997-2006. In 2006, six pathogenic bacterial strains were isolated from two symptomless seed samples of rice （Oryza sativa L.） originally produced in Hainan Province and then planted in Zhejiang Province, China. They were identified as Burkholderia glumae which is the causal organism of bacterial grain rot of rice by physiological characteristics, colony morphology, pathogenicity test, Biolog, fatty acid methyl ester （FAME） analysis and RAPD-PCR compared with the four standard reference strains. It is confirmed that there is the infection of B. glumae in so-called ＇health looking seeds＇.

Serum-Derived Bovine Immunoglobulin/Protein Isolate Therapy for Patients with Refractory Irritable Bowel Syndrome

Background: A small double-blind study showed benefits of serum-derived bovine immunoglobulin/protein isolate (SBI), for diarrhea-predominant irritable bowel syndrome (IBS-D) [1]. The purpose of this chart review was to assess safety and clinical outcomes of SBI in refractory irritable bowel syndrome (IBS) patients. Methods: A retrospective review of 35 IBS patients with diarrhea or mixed diarrhea/constipation pattern (IBS-M) who were administered SBI 5 grams twice daily was performed. Clinical response (“good response” or “no response”) and adverse events were determined by follow-up after four weeks of therapy. Patients were included for evaluation if a lactulose breath test (LBT) had been performed prior to SBI. All patients were refractory to common IBS therapies. The response rate to the inclusion of SBI was calculated in three separate groups: dividing patients based on their LBT results (positive or negative), dividing patients by their IBS diagnosis (IBS-D or IBS-M) and grouping all patients together. Results: Analysis was carried out on 26 IBS-D/-M patients with LBT results. Two patients were lost to follow-up and were excluded from data analysis. The positive LBT group (N = 11) had a 73% (p = 0.117) positive response rate to SBI. The negative LBT group (N = 13) had a significant response rate of 77% (p = 0.040). If patients were divided by IBS diagnosis or grouped together, the response rate to SBI was similarly ranging from 69% - 88%. Adverse events leading to cessation of SBI occurred in 3 of 24 patients. Conclusion: SBI appeared to be a safe and effective nutritional moiety in refractory IBS-D and IBS-M patients. Larger, double-blind studies are needed.

Antibiotic Resistant Bacteria from Treated and Untreated Hospital Wastewater at Ayder Referral Hospital, Mekelle, North Ethiopia

The widespread emergence of antibiotic resistance among bacterial pathogens has become one of the most serious challenges in Ethiopia. This study determined the prevalence and drug resistance patterns of bacterial pathogens isolated from treated and untreated wastewater released from Ayder Referral Hospital in Northern Ethiopia. A cross sectional study design was conducted from September-December, 2015 in wastewater released from Ayder referral hospital. A total of 40 composite samples were aseptically collected, transported and processed for enumeration of indicator organisms, bacteriological identification and susceptibility testing following standard procedure. Data obtained were entered and analyzed using SPSS version 20. Mean heterotrophic plate count, total coliform count, fecal coliform count and E. coli count were found to be 1.6 × 106 CFU/mL, 2.2 × 106 CFU/100 mL, 2.0 × 105 CFU/100 mL and 1.1 × 104 CFU/100 mL from treated wastewater respectively. Among the total samples 134 bacterial isolates were detected and [84 (62.7%)] were from untreated wastewater and [50 (37.3%)] were from treated wastewater. The most frequently isolated bacteria from untreated wastewater samples was Klebsiella spp [14 (16.7%)] followed by S. aureus [13 (15.5%)] and P. aeruginosa [12 (14.3%)], similarly in treated wastewater samples Klebsiella spp [10 (20%)], P. aeruginosa [8 (16%)] and S. aureus [8 (16%)] were frequently detected. The overall multi-drug resistance (MDR) in this study was [79/134 (79.1%)]. MDR from untreated wastewater sample was [64/84 (76.2%)] while from treated wastewater sample was [42/50 (84%)] and shows significant difference with (COR: 1.64, 95% CI: 1.15 - 3.29, P: 0.001). It is concluded that treated hospital wastewater contains large numbers of antibiotic resistant bacteria. Therefore, there should be continuous monitoring and evaluation of the effluent quality of the ponds and chlorination of the final effluent should be developed.

Soil bacterial and fungal community successions under the stress of chlorpyrifos application and molecular characterization of chlorpyrifos-degrading isolates using ERIC-PCR

Chlorpyrifos is a widely used insecticide in recent years,and it will produce adverse effects on soil when applied on crops or mixed with soil.In this study,nested polymerase chain reaction（PCR） and denaturing gradient gel electrophoresis（DGGE） were combined to explore the bacterial and fungal community successions in soil treated with 5 and 20 mg/kg of chlorpyrifos.Furthermore,isolates capable of efficiently decomposing chlorpyrifos were molecular-typed using enterobacterial repetitive intergenic consensus-PCR（ERIC-PCR）.Under the experimental conditions,degradation of chlorpyrifos in soil was interpreted with the first-order kinetics,and the half-lives of chlorpyrifos at 5 and 20 mg/kg doses were calculated to be 8.25 and 8.29 d,respectively.DGGE fingerprint and principal component analysis（PCA） indicated that the composition of the fungal community was obviously changed with the chlorpyrifos treatment,and that samples of chlorpyrifos treatment were significantly separated from those of the control from the beginning to the end.While for the bacterial community,chlorpyrifos-treated soil samples were apparently different in the first 30 d and recovered to a similar level of the control up until 60 d,and the distance in the PCA between the chlorpyrifos-treated samples and the control was getting shorter through time and was finally clustered into one group.Together,our results demonstrated that the application of chlorpyrifos could affect the fungal community structure in a quick and lasting way,while only affecting the bacterial community in a temporary way.Finally,nine typical ERIC types of chlorpyrifos-degrading isolates were screened.

Bacterial Resistance in Clinical Isolates of Klebsiella Pneumoniae

Ninety-four percent of 336 strains Klebsiellapneumoniae were resistant to ampicillin，while less than 10％were resistant to cefotaxine and ceftazidine.Among all theaminoglycosides tested,amikacin had the strongest activity on K.

Detection of Gram-Negative Bacteria Carrying the blaKPC-2 Gene from Mangrove Sediments

Mangroves are environments that have fast cycles associated with high concentration of bacterial decomposers.These are impacted by anthropogenic pollution due to contamination of bacterial species carrying resistance genes.This study aims to evaluate the metabolic profile of the microbiota in mangrove sediments,and verify the presence of Gram-negative bacteria resistant to meropenem.The samples were obtained from location along the Anil river and were seeded in medium supplemented with the antibiotic meropenem in increasing concentrations.The DNA was analyzed by multiplex PCR for detecting resistance genes forβ-lactam antibiotics.The bacteria were identified by Matrix-assisted laser desorption ionization–time of flight mass spectrometry(MALDI-TOF MS).The genes were sequenced by ABI PRISM 3100,analyzed by MEGA 6.0 program,and the sequence identified was assessed by GenBank using the BLAST algorithm.Ecoplate■the kit was used to determine the metabolic profile of the microbiota.The results of the six bacterial isolates showed the blaKPC-2 gene and were identified as Stenotrophomonas maltophilia and Pseudomonas putida.The samples showed a greater diversity Shannon index,a rich substrate consumption and high equity.There was a metabolic richness such as carbon consumption profiles,being a factor of adaptation of pathogenic bacteria carrying resistance genes toβ-lactamics antibiotics.

邯郸地区不同类型高温大曲细菌群落与理化特性差异性分析

该研究采用高通量测序技术对不同类型高温大曲细菌群落进行了解析,继而对其理化指标进行测定,同时对2者的相关性进行分析,最后使用纯培养技术对细菌资源进行挖掘。测序结果表明,黄色高温大曲中Thermoactinomyces、Limosilactobacillus和Weissella的平均相对含量显著偏高(P<0.05),分别为21.04%、14.30%和3.15%,Lentibacillus和Kroppenstedtia的平均相对含量显著偏低(P<0.05),分别为3.30%和2.81%,而其在黑色高温大曲中分别为1.93%、0.036%、0.027%、34.45%和20.75%。此外,LEfSe分析发现Thermoactinomyces和Lentibacillus可分别作为黄色和黑色高温大曲的生物标志物。理化指标测定显示,黄色高温大曲的水分含量、液化力、糖化力、酯化力和酒化力显著偏高(P<0.05),而酸度显著偏低(P<0.05)。相关性分析发现,优势细菌属与理化指标之间存在显著相关性(P<0.05)。采用纯培养技术从高温大曲样品中共分离得到33株细菌菌株,鉴定为5个属的10个种,主要以Bacillus为主,且B.licheniformis为优势分离株,占分离株总数的30.30%。由此可见,2种类型高温大曲细菌群落与理化指标间均存在明显差异,且微生物与理化指标之间具有一定相关性。

粤东上升流区不同水层可培养细菌多样性

上升流通过增强扩散和独特的环境驱动着近海生态系统中的物质循环和能量流动,直接影响环境中生物的生长、繁殖和分布,蕴藏了大量尚未培养和难培养的微生物和新基因资源。本研究从粤东上升流区表层、中层和底层共采集27份海水样品,探究细菌多样性和分布模式及其与深度的相关性。采用纯培养方法共分离获得1928株细菌,通过16S rRNA基因序列分析,结果显示这些细菌分布在5门、9纲、32目、54科、121属中的262种。其中,变形菌门(Proteobacteria)为优势门,占46.9%;放线菌纲(Actinomycetia)为优势纲,占44.8%;Microbacteriales为优势目级类群,占21.2%。总体来说,中层海水分离得到的菌株多样性明显低于表层和底层海水环境,但三个层级环境分离获得的优势种群基本相同,最优类群均为Microbacteriales目。从不同水层海水中分离得到的潜在新菌数排序为:底层>表层>中层。从不同培养基分离得到的潜在新菌率排序为2216E培养基>R2A培养基>ISP2培养基>MSM培养基>IMK培养基。通过细菌多样性与环境因子的典范对应分析(canonical correspondence analysis,CCA)表明,能显著影响细菌多样性变化的环境因子是叶绿素含量(chlorophyll content,Chl)、活性硅酸盐(active silicate salts,ASS)、活性磷酸盐(active phosphate,AP)、氨及部分氨基酸(ammonia,Amm)和生化需氧量(biochemical oxygen demand,BOD)。本研究系统调查了粤东上升流区可培养海洋细菌多样性及其分布情况,其结果为近海上升流区不同水层可培养细菌多样性研究积累了关键的资料和数据,也为近海典型上升流环境生物物种和基因资源的发掘和利用提供了重要参考。