Non-agricultural sources of pesticides in urban areas are responsible for their presence in domestic wastewater. Therefore, pesticides are typically found in sewage treatment plants in developed and ...developing countries as micro-pollutant. The presence of pesticides in the wastewater can impart stress on the aerobic sludge biomass and disrupt the functioning of the plant. However, there exists a knowledge gap regarding the resilience of aerobic sludge biomass towards stress due to the presence of pesticides in the wastewater. This study investigated the impact of chlorpyrifos (CPS) – a widely used pesticide, on sludge biomass and explored its recovery capability when CPS is discontinued in the influent. Four duplicate reactors were operated with different CPS concentrations ranging from 50 to 200 mg/L. Chemical oxygen demand (COD) removal for reactors has ranged within 18–73 % at the steady state of the stressed phase, whereas COD removal for the control reactor was 91 %. CPS stress slightly inhibited filamentous biomass growth. Biomass activity and cell viability have decreased significantly, whereas biochemical contents have varied slightly under CPS stress. The activities of the enzymes dehydrogenase and urease were significantly inhibited when compared to catalase and protease. Amplified ribosomal DNA restriction analysis reflected changes in the microbial community. The discontinuation of CPS has allowed aerobic sludge biomass to recover in its organic degradation capability (COD removal of more than 88 % at steady-state conditions of recovery phase operation), biomass growth, and cell viability. In addition, enzyme activities have retrieved to their original levels, and 78–93 % similarity of microbial community structure has been displayed between CPS-exposed and control reactor biomasses. Overall, the present study has indicated the orderly changes in the quality of aerobic sludge biomass under CPS stress through physico-chemical and biological characteristics. The study also has highlighted the self-recovery of sludge biomass characteristics stressed with different concentrations of CPS.
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•CPS impacts on sludge biomass were assessed.•Organics removal efficiency was reduced drastically under CPS stress.•Biomass activity and cell viability were decreased significantly.•Enzymes activities viz. dehydrogenase and urease exhibited significant inhibition.•Sludge biomasses have completely recovered from CPS stress.
The increasing interest in the use of rhizobia as biofertilizers in smallholder agricultural farming systems of the Sub-Saharan Africa has prompted the identification of a large number of tropical ...rhizobia strains and led to studies on their diversity. Inoculants containing diverse strains of rhizobia have been developed for use as biofertilizers to promote soil fertility and symbiotic nitrogen fixation in legumes. In spite of this success, there is paucity of data on rhizobia diversity and genetic variation associated with the newly released and improved mid-altitude climbing (MAC) bean lines (
L.). In this study, 41 rhizobia isolates were obtained from the root nodules of MAC 13 and MAC 64 climbing beans grown in upper and lower midland agro-ecological zones of Eastern Kenya. Eastern Kenya was chosen because of its high production potential of diverse common bean cultivars. The rhizobia isolates were characterized phenotypically on the basis of colony morphology, growth and biochemical features. Rhizobia diversity from the different regions of Eastern Kenya was determined based on the amplified ribosomal DNA restriction analysis (ARDRA) of PCR amplified 16S rRNA genes using
I,
I, and
III restriction enzymes. Notably, native rhizobia isolates were morphologically diverse and grouped into nine different morphotypes. Correspondingly, the analysis of molecular variance based on restriction digestion of 16S rRNA genes showed that the largest proportion of significant (
< 0.05) genetic variation was distributed within the rhizobia population (97.5%) than among rhizobia populations (1.5%) in the four agro-ecological zones. The high degree of morphological and genotypic diversity of rhizobia within Eastern Kenya shows that the region harbors novel rhizobia strains worth exploiting to obtain strains efficient in biological nitrogen fixation with
L. Genetic sequence analysis of the isolates and testing for their symbiotic properties should be carried out to ascertain their identity and functionality in diverse environments.
Background: Molecular identification of a wide range of organisms capable of carrying out biological nitrogen fixation (BNF) are diverse in nature and significantly improves plant growth. Biological ...N2 fixation reflects the activity of a phylogenetically diverse list of microorganisms. Molecular characterization provides efficient means to identify organisms with the potential of N2 fixation. Applying these techniques in an array of environments has considerably broadened our understanding of the suite of organisms that can carry out BNF.
Methods: Thirty-four strains of free living N2 fixing bacterial strains were isolated from diverse plants cultivated in North Gujarat, including wheat, cotton, castor and pearl millet, using a nitrogen-free selective medium. Acetylene reduction assay was used to check the ability of all bacteria to fix nitrogen. Hybridization with nifH probe derived from Azotobacter vinelandii with isolated free-living nitrogen-fixing bacteria showed a positive result. The selected strains were characterized by molecular analysis like; ARDRA and 16S rDNA sequencing. Result: Based on molecular characterization 17 strains to known groups of nitrogen-fixing bacteria, including organisms from the genus Azotobacter, Pseudomonas, Enterobacter, Arthrobacter, Bacillus, Variovorax, Nocardiodies, Rhodococcus, Mycobacterium, Planococcus, Microbacterium have been identified. One of the strains was identified as unknown bacteria. The potential strains were identified by 16srDNA analysis and also corroborated by morphological and biochemical characterization.
•Lactic acid bacteria isolates were screened on the human gastrointestinal system.•Antibiotic susceptibility of potentially probiotic isolates was tested.•Lactic acid bacteria isolates were analyzed ...for the 16S rDNA by ARDRA and RAPD.•Lactobacillus acidophilus, Lactobacillus planetarum and Lactobacillus fermentum were found.
Lactobacillus species are beneficial for the functional food industry and preventive medicine. The complex microflora of traditional cheese depends on the cheese types (e.g., homemade rennets). Here, the abomasum driven rennet was assessed for the existence of lactobacilli. For differentiating lactobacilli, the bacterial suspension was screened for the acid and bile resistance. The isolated bacteria were evaluated for antibiotic susceptibility and antagonistic impacts on other pathogenic bacteria. The 16S rDNA gene was evaluated by the amplified ribosomal DNA restriction analysis (ARDRA) recruiting the restriction enzyme Taq I and compared to the virtually digested patterns of previous reports on lactobacilli. The isolates were examined by random amplified polymorphic DNA (RAPD) and distinctive lactobacilli were sequenced. ARDRA and RAPD data showed three distinct lactobacilli strains, including L. acidophilus, L. planetarum, and L. fermentum. The homemade rennet is proposed as the novel source of probiotic strains as an alternative to the traditional cheeses.
Carbapenem-resistant determinants and their surrounding genetic structure were studied in Acinetobacter spp. from neonatal sepsis cases collected over 7 years at a tertiary care hospital. ...Acinetobacter spp. (n = 68) were identified by ARDRA followed by susceptibility tests. Oxacillinases, metallo-β-lactamases (MBLs), extended-spectrum β-lactamases and AmpCs, were detected phenotypically and/or by PCR followed by DNA sequencing. Transconjugants possessing the bla NDM-1(New Delhi metallo-β-lactamase) underwent further analysis for plasmids, integrons and associated genes. Genetic environment of the carbapenemases were studied by PCR mapping and DNA sequencing. Multivariate logistic regression was used to identify risk factors for sepsis caused by NDM-1-harboring organisms. A. baumannii (72%) was the predominant species followed by A. calcoaceticus (10%), A. lwoffii (6%), A. nosocomialis (3%), A. junni (3%), A. variabilis (3%), A. haemolyticus (2%), and 14TU (2%). Fifty six percent of the isolates were meropenem-resistant. Oxacillinases present were OXA-23-like, OXA-58-like and OXA-51-like, predominately in A. baumannii. NDM-1 was the dominant MBL (22%) across different Acinetobacter spp. Isolates harboring NDM-1 also possessed bla (VIM-2, PER-1, VEB-2, CTX-M-15), armA, aac(6')Ib, aac(6')Ib-cr genes. bla NDM-1was organized in a composite transposon between two copies of ISAba125 in the isolates irrespective of the species. Further, OXA-23-like gene and OXA-58-like genes were linked with ISAba1 and ISAba3 respectively. Isolates were clonally diverse. Integrons were variable in sequence but not associated with carbapenem resistance. Most commonly found genes in the 5' and 3'conserved segment were aminoglycoside resistance genes (aadB, aadA2, aac4'), non-enzymatic chloramphenicol resistance gene (cmlA1g) and ADP-ribosylation genes (arr2, arr3). Outborn neonates had a significantly higher incidence of sepsis due to NDM-1 harboring isolates than their inborn counterparts. This study demonstrates the significance of both A. baumannii and other species of Acinetobacter in cases of neonatal sepsis over an extended period. Oxacillinases and bla NDM-1 are the major contributors to carbapenem resistance. The dissemination of the bla NDM-1 is likely linked to Tn125 in diverse clones of the isolates.
Many species or strains of the genus Pseudomonas have been characterized as plant growth promoting rhizobacteria (PGPR). We used a combination of phenotypic and genotypic techniques to analyze the ...community of fluorescent Pseudomonas strains in the rhizosphere of commercially grown Mentha piperita (peppermint). Biochemical techniques, Amplified rDNA Restriction Analysis (ARDRA), and 16S rRNA gene sequence analysis revealed that the majority of the isolated native fluorescent strains were P. putida. Use of two Repetitive Sequence-based PCR (rep-PCR) techniques, BOX-PCR and ERIC-PCR, allowed us to evaluate diversity among the native strains and to more effectively distinguish among them. PGPR activity was tested for the native strains and reference strain P. fluorescens WCS417r. Micropropagated M. piperita plantlets were exposed to microbial volatile organic compounds (mVOCs) emitted by the bacterial strains, and plant biomass parameters and production of essential oils (EOs) were measured. mVOCs from 11 of the native strains caused an increase in shoot fresh weight. mVOCs from three native strains (SJ04, SJ25, SJ48) induced changes in M. pierita EO composition. The mVOCs caused a reduction of metabolites in the monoterpene pathway, for example menthofuran, and an increase in menthol production. Menthol production is the primary indicator of EO quality. The mVOCs produced by native strains SJ04, SJ25, SJ48, and strain WCS417r were analyzed. The obtained mVOC chromatographic profiles were unique for each of the three native strains analyzed, containing varying hydrocarbon, aromatic, and alogenic compounds. The differential effects of the strains were most likely due to the specific mixtures of mVOCs emitted by each strain, suggesting a synergistic effect occurs among the compounds present.
Piggery wastewater (PWW) contains a variety of pollutants, and lack of treatment infrastructure in piggery farms often results in the discharge of PWW into nearby drains, eventually reaching sewage ...treatment plants. It may adversely affect the sludge biomass of the treatment plants. This study investigated the effects of prolonged exposure to PWW and copper-laden (40 and 80 mg/L) PWW on the quality of sludge biomass. The results revealed that PWW-exposed reactors experienced a significant decrease in COD removal (65–76% compared to 95% in the control reactor). Additionally, there were changes in sludge characteristics, including a decreased sludge volume index (SVI) and an increased interface settling velocity (ISV). Further addition of PWW+Cu(II) stress significantly reduced COD removal (8–29%), the filamentous index and also lowered cell viability and enzyme activity. However, partial recovery was observed after discontinuing PWW+Cu(II) exposure, particularly at 40 mg/L of Cu(II) concentration. The study is significant for practical wastewater treatment, as it deals with multi-stress conditions caused due to Cu(II) metal laden piggery wastewater. The investigation recommends preliminary tests (microscopic examination and aerobic sludge biomass activity test) and confirmatory tests (cell viability tests and amplified ribosomal DNA restriction analysis) to be used for the evaluation of aerobic sludge biomass quality.
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•Study evaluates the influence of Cu(II) laden Piggery Wastewater (PWW) on sludge biomass and potential recovery.•Only PWW exposure affected COD removal, disintegrated floc structure, and lowers enzyme activities.•PWW+Cu(II) exposure led to decrease COD removal, cell viability, and enzyme activity inhibition.•Sludge biomasses partially recovered upon removal of PWW+Cu(II), especially at higher Cu(II) doses.
Bacteria may adhere to and develop biofilm structures onto dairy surfaces trying to protect themselves from adverse conditions such as pasteurization and CIP processes. Thus, biofilms are considered ...common sources of food contamination with undesirable bacteria. The purpose of this study was to evaluate the diversity of the microbiota attached to stainless steel surfaces in pre- and post-pasteurization pipe lines of a milk-processing plant. Seventy Gram-positive isolates were identified as
Enterococcus faecalis
(33),
Bacillus cereus
(26),
Staphylococcus hominis
(8),
Staphylococcus saprophyticus
(2), and
Staphylococcus epidermidis-Staphylococcus aureus
(1) species. Fifty-five Gram-negative isolates were identified to the species
Escherichia coli
(18),
Klebsiella pneumoniae
(13),
Acinetobacter calcoaceticus
(6),
Serratia marcescens
(6),
Enterobacter
spp. (5),
Pseudomonas aeruginosa
(4),
Escherichia vulneris
(2), and
Proteus mirabilis
(1). Fifty-five different strains were detected by the RAPD technique. These were subjected to an
in vitro
assay to evaluate their biofilm-forming capability.
E. faecalis
(7),
A. calcoaceticus
(4),
K. pneumoniae
(3),
S. hominis
(3), and
P. aeruginosa
(2) were the species in which more biofilm producer strains were encountered. The adhered microbiota was also assessed by the PCR-DGGE culture-independent technique. This analysis revealed a greater bacterial diversity than that revealed by culturing methods. In this way, in addition to the bacteria detected by culturing, DNA bands belonging to the genera
Chrysobacterium
and
Streptomyces
were also identified. This study emphasizes that knowledge of attached microorganisms to dairy surfaces may help develop strategies to improve optimal operational parameters for pasteurization and CIP processes in dairy plants.
Abstract
Kiwifruit bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) is a severe global disease. However, effective biological control agents for controlling Psa are currently ...unavailable. This study aimed to screen potential biological control agents against Psa from the kiwifruit rhizosphere. In this study, a total of 722 isolates of bacteria were isolated from the rhizosphere of kiwifruit orchards in five regions of China. A total of 82 strains of rhizosphere bacteria showed antagonistic effects against Psa on plates. Based on amplified ribosomal DNA restriction analysis (ARDRA), these antagonistic rhizosphere bacteria were grouped into 17 clusters. BLAST analyses based on 16S rRNA gene sequence revealed 95.44%–100% sequence identity to recognized species. The isolated strains belonged to genus Acinetobacter, Bacillus, Chryseobacterium, Flavobacterium, Glutamicibacter, Lysinibacillus, Lysobacter, Pseudomonas, Pseudarthrobacter, and Streptomyces, respectively. A total of four representative strains were selected to determine their extracellular metabolites and cell-free supernatant activity against Psa in vitro. They all produce protease and none of them produce glucanase. One strain of Pseudomonas sp. produces siderophore. Strains of Bacillus spp. and Flavobacteria sp. produce cellulase, and Flavobacteria sp. also produce chitinase. Our results suggested that the kiwifruit rhizosphere soils contain a variety of antagonistic bacteria that effectively inhibit the growth of Psa.
Kiwifruit rhizosphere contains a variety of antagonistic bacteria that effectively inhibit the growth of Psa.
Aim: The aim of this study was to use Ascophyllum nodosum for potentially increasing the growth and rhizobial diversity in nodulating rhizobia in Vigna aconitifolia. Methodology: Different ...concentrations of Ascophyllum nodosum extracts (0.01%, 0.02%, 0.05%, 0.10% and 0.50%) were applied via foliar spray and on roots of Vigna aconitifolia. Growth characteristics and Amplified Ribosomal DNA Restriction Analysis were conducted to detect the morphological and molecular changes in rhizobial diversity. The restriction profiles thus obtained were used to study the rhizobial communities via Cluster analysis and Dendrogram using NTSYS-PC program and UPGMA constructed. Results: Roots treated with 0.05% Ascophyllum nodosum extract showed best growth of plants. This concentration not only proved best for the aggregation of nodules but also for obtaining enormous rhizobial diversity. Interpretation: Ascophyllum nodosum is a modern, cheap, non-toxic natural biofertilizer and Amplified Ribosomal DNA Restriction Analysis represents a favorable alternative to culture dependent method for assessing rhizobial diversity in nodulating bacteria.
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