Isolation Of Heterotrophic Bacteria Research Articles

Fungicidal and Bactericidal Activity of the Alkyl-Substituted Guanidine-Containing Oligomers

Biocides are widely used in medicine and various industries to protect against a number of harmful microorganisms. Organic quaternary ammonium and guanidine-containing compounds, the biological action of which is based on membrane-toxic properties, are used as bactericidal preparations. The aim of this work was to study the bactericidal and fungicidal activities of the synthesized oligomeric alkylsubstituted guanidinium bromides with different radicals -C3H7, -C7H15, -C10H21, against different isolates of heterotrophic bacteria and microscopic fungi. Methods. The synthesis of alkyl-substituted guanidiniumcontaining oligomers was performed in two stages. In the first stage, alkyl-substituted guanidine was obtained by the reaction of guanidine, previously converted by alkali from the salt form to the base form by the base and alkyl bromides (Alk=-C3H7 (propyl), -C7H15 (heptyl), -C10H21 (decyl)) in methanol at a temperature of 50°C and a molar ratio of 1:1. The second carried out the reaction between aromatic oligoepoxide DER-331 and alkyl-substituted guanidine in methanol at a temperature of 50°C for 2–3 hours and a molar ratio of 1:2. Bacteria were grown on meat-peptone agar for 48 hours at a temperature of 28±2°С. Test cultures of micromycetes were cultured on agar beer wort (6°B), incubated for 14 days in a thermostat at a temperature of 28±2°C. Antimicrobial activity of newly synthesized alkyl-substituted guanidinium-containing oligomers was determined by standard disco-diffusion method (method of disks on agar) and fungicidal activity was determined by the method of holes in agar. Results. Oligomeric alkylsubstituted guanidinium bromides with different radicals composed -C3H7, -C7H15, -C10H21- synthesized by the reaction of guanidine alkyl bromides with aromatic oligoepoxydes. It was found that alkyl-substituted guanidinium-containing oligomers at a concentration of 1–3% inhibited the growth of Escherichia coli 475, Pseudomonas aeruginosa 465, Klebsiella pneumonia 479, Pseudomonas pseudoalcaligenes 109, Staphylococcus aureus 451, E. faecalis 422, Rhodococcus erythropolis 102, Bacillus subtilis 138 and most of the studied micromycetes – Aureobasidium pullulans F-41430, Paecilomyces variotii F-41432, Penicillium funiculosum F-41435, Penicillium ochrochloron F-41431, Scopulariopsis brevicaulis F-41434, Trichoderma viride F-41437, Candida albicans F-41441, Aspergillus flavus F-41442, Aspergillus niger F-41448, Penicillium sp. F-41447. Conclusions. Antimicrobial and fungicidal properties significantly depend on the length of the alkyl radical, with increasing of its length the diameter of the zone of bacterial and micromycetes growth retardation increases.10.15407/microbiolj82.06.054

Isolation of heterotrophic bacteria from Palk Bay sediments showing heavy metal tolerance and antibiotic production

Analysis of culturable and unculturable bacteria and their potential bioactive compounds from Palk Bay is yet to be explored. The present study for the first time characterizes the culturable bacteria from Palk Bay sediment using 16S rRNA gene sequencing. The characterized bacteria were also screened for antibacterial activity against human and aquaculture pathogens. In the 16S rRNA gene sequence analysis characterized that most of the bacteria were affiliated to members of Firmicutes and less with Gammaproteobacteria, Actinobacteria and Alphaproteobacteria. A high portion of (39%) of the bacteria showed antibacterial activity against both Gram positive and Gram negative test strains. The antibiotics from the strain S6-05 were partially purified using solvent extraction followed by TLC and silica column and further characterized by IR analysis. Two active principles A and B showed difference in the activity against Gram positive and Gram negative pathogens. But in the synergistic application they showed excellent activity against all the test pathogens. This study provides the first evidence on the existence of certain Bacillus species in the marine environment, namely Bacillus arsenicus, Bacillus indicus, Bacillus boroniphilus, Bacillus cibi and Bacillus niabensis which also had antibacterial activity. Several of the isolates exhibited tolerance to arsenic and boron to a new level of 25 and 100 mM, respectively. The current study reveals the fact that a great deal remains in the bacterial diversity of Palk Bay region.

Comparison of a novel MPN method against the yeast extract agar (YEA) pour plate method for the enumeration of heterotrophic bacteria from drinking water

This study compared the Quanti-Disc ™ most probable number (MPN) test for heterotrophic bacteria from drinking water with the widely used yeast extract agar (YEA) pour plate method. The Quanti-Disc ™ test module contains 50 reaction wells in which a medium has been pre-deposited. The medium contains a suite of three fluorogenic enzyme substrates selected for the detection of enzymes expressed widely by heterotrophic bacteria. The MPN of heterotrophic bacteria is calculated from the number of fluorescing reaction wells after incubation of a sample. Quanti-Disc ™ and the YEA pour plate method were compared according to guidance on comparing methods given in United Kingdom national guidance and ISO 17994:2004. The two methods were also challenged with reference strains and isolates of heterotrophic bacteria from drinking water. This indicated that heterotrophic bacteria commonly encountered in drinking water are detected by both the YEA pour plate method and Quanti-Disc ™. Analysis of data from split water samples (723 for 37 °C tests and 872 for 22 °C tests) from nine geographically diverse laboratories in England and Wales demonstrated that the Quanti-Disc ™ method is equivalent to the YEA pour plate method for the analysis of heterotrophic bacteria from drinking and similar waters at 37 °C, and superior to YEA for the analysis at 22 °C. The Quanti-Disc ™ method is a simple and efficient alternative method for the enumeration of heterotrophic bacteria from drinking water.

Identity and Potential Functions of Heterotrophic Bacterial Isolates from a Continuous-Upflow Fixed-Bed Reactor for Denitrification of Drinking Water with Bacterial Polyester as Source of Carbon and Electron Donor

A collection of 186 heterotrophic bacteria, isolated directly from a continuous-upflow fixed-bed reactor for the denitrification of drinking water, in which poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) granules acted as biofilm carrier, carbon source and electron donor, was studied with regard to taxonomic affiliation and degradation and denitrification characteristics. Two granule samples were taken from a fully operating reactor for enumeration and isolation of heterotrophic bacteria. One sample was drawn from the lower part of the reactor, near the oxic zone, and the other sample from the upper, anoxic part of the fixed bed. Dominant colonies were isolated and the cultures were identified using fatty acid analysis and 16S rDNA sequencing. Their ability to degrade the polymer and 3-hydroxybutyrate and to denitrify in pure culture was assessed. The results show that high numbers of heterotrophic bacteria were present in the biofilms on the polymer granules, with marked differences in taxonomic composition and potential functions between the lower and upper part of the fixed bed. The majority of the isolates were Gram negative bacteria, and most of them were able to reduce nitrate to nitrite or to denitrify, and to utilize 3-hydroxybutyrate as sole source of carbon. Only two groups, one identified as Acidovorax facilis and the other phylogenetically related to Brevundimonas intermedia, could combine denitrification and utilization of poly(3-hydroxybutyrate) (PHB), and were found only in the upper sample. The other groups occurred either in the lower or upper part, or in both samples. They were assigned to Brevundimonas, Pseudomonas, Agrobacterium, Achromobacter, or Phyllobacterium, or were phylogenetically related to Afipia or Stenotrophomonas.

Assessment of microbiological quality for swimming pools in South America

Concerning the great importance of the safety of bathing water, and due to the dispute about the better microbiological indicator to assess the water quality of swimming pools, 1345 samples of water collected from 60 swimming pools in a period of four years were analyzed for total (TC) and fecal coliforms (FC), fecal streptococci (FS), heterotrophic bacteria (HPC), S. aureus (Sa), C. albicans (Ca) and P. aeruginosa (Pa). The frequency of positive results for these indicators ranged up to 70.4% (HPC), 13.3% (TC), 9.1% (Sa), 7.7% (FS), 5.6% (FC) and 2.0% (Pa and Ca). A correlation matrix (Spearman rank correlation) showed strong positive relationship among the levels of these microorganisms and between their densities and bather load and water temperature. As expected, all the microbiological variables presented a negative correlation with chlorine, C. albicans showing to be the more resistant to this disinfectant. Considering the good correlation among all these microbiological parameters, the highest rates of isolation of heterotrophic bacteria and total coliforms and the costs for microbiological analysis, it is possible to achieve an effective monitoring of swimming pool water quality by using only these two indicators, with no need of applying the other ones on a routine basis. P. aeruginosa and C. albicans, besides their high resistance to chlorine, presented a very low incidence and its use for evaluating swimming pool waters quality in routine is not indicated.

Soil heterotrophic bacteria in transformations of inorganic sulphur

The occurrence of biochemical activities of the sulphur cycle was followed in isolates of heterotrophic bacteria from the fermentative horizon of a spruce stand, a grass-covered withered spruce stand and of mountain ash and birch stand in the area strongly influenced by sulphur immissions. The occurrence of bacteria capable of reducing S0 to S2−, oxidizing S0 and S2O3 2− to SO4 2− and solubilizing S0 increased in the above order. The occurrence of producers of thiosulphate sulphurtransferase (rhodanese), thiosulphate oxidase and sulphite oxidase increased and the level of the production of these enzymes increased as well. Heterotrophic bacteria (mostly pseudomonads) from the grass-covered stands exhibit more activities of the sulphur cycle than bacteria from the spruce stand without ground vegetation.