Development Of Bacterial Colonies Research Articles

ISOLATION OF METHANOTROPHIC BACTERIA FROM NATURAL BIOCENOSES AND SELECTION OF NUTRIENT MEDIA OPTIMAL FOR CULTIVATION IN LABORATORY CONDITIONS

Background. One of the most pressing problems in the world is the production of food protein. The global protein deficit is estimated at 30 million tons per year, for the Russian Federation it is estimated at 2-2.5 million tons of protein per year.
 The problem of protein deficit can be partially solved with the help of methanotrophic bacteria. Under optimal conditions, methanotrophic bacteria are able to oxidise actively natural gas – methane and increase their biomass, rich in valuable protein, vitamins and other biologically active substances. The feed product from methanotrophic bacteria is comparable to fish meal and soybean meal, the concentration of pure protein in it is more than 80%.
 Purpose. Isolation of methanotrophic bacteria from natural biocenoses and their cultivation on various nutrient media in laboratory conditions.
 Materials and Methods. The study was conducted from 2019 to 2022 in the microbiological laboratory of the Center for Technological Excellence “Advanced Chemical and Biotechnology” of the Tolstoy Tula State Pedagogical University. The object of the study was methanotrophic bacteria isolated from various natural and artificial ecosystems, collection strains of Methylococcus capsulatus B-2990 and Methylomonas methanica B-2110. To isolate methanotrophic bacteria, the method of seeding a accumulative culture on a solid agiarized sterile nutrient medium in Petri dishes was used. For the cultivation of methanotrophs, nutrient media of various compositions containing all the necessary macro- and microelements for the normal growth of bacterial colonies were used.
 Results. Colonies of methanotrophic bacteria were found in one sample of bottom sediments taken from the sphagnum swamp of the village of Kochaki in the Tula region and in samples from a methane reactor. As a result of comparison of nutrient media for isolation and cultivation of methanotrophs, it was found that the most suitable medium for isolation of methanotrophic bacteria is the standard nitrate mineral medium NMS. For the cultivation of methanotrophic bacteria, the best media were: the nutrient medium with the addition of anaerobic sludge, the ammonium mineral nutrient medium (AMS), and AMS with addition of methanol, the nutrient medium No.221 with addition of methanol.
 Conclusions. The use of various nutrient media for the cultivation of methanotrophic bacteria makes it possible to assess the effect of various organic substances on the growth and development of bacterial colonies. The study of various natural and artificial ecosystems makes it possible to expand taxonomic knowledge about this group of microorganisms, as well as to increase the potential of using methanotrophs in solving various problems of ecology and biotechnology.

Evaluation of the antibacterial and antibiofilm activities of sodium benzoate against the soft rot disease of tomato in Iraq

Pectobacterium carotovorum is one of the most serious pectolytic bacterial pathogens causing significant pre- and postharvest soft rot diseases on a variety of agroeconomic fruits and vegetables worldwide. Application of chemical pesticides for controlling the postharvest diseases is still insufficient and unacceptable by consumers. The effect of sodium benzoate (C6H5COONa) (SBN) was evaluated against the growth of P. carotovorum utilizing the highly pathogenic strain BR03, confirmed molecularly using dnaA primers. The inhibition zone was the greatest when P. carotovorum was treated with 600 mM SBN both at pH 7.5 and 7.0. Flow cytometry (distinguishing live and dead bacterial cells) and the development of bacterial colonies on Petri plates confirmed the bactericidal action of SBN. In addition, these results validated that bacterial cells were killed when treated with 600 mM SBN. The biofilm formation was completely inhibited and destroyed following exposure to 600 mM SBN after a 24-h incubation period and the absorbance readings were reduced as the concentration of SBN increased. Disease severity on inoculated tomato fruits decreased in comparison with the control fruit at either 4 or 25 °C. SBN is safe for human health and commonly used in industries as a food preservative. SBN can be an effective alternative method for controlling soft rot diseases on tomato fruits.

Controlling Geometry and Flow Through Bacterial Bridges on Patterned Lubricant-Infused Surfaces (pLIS).

Spatial control of bacteria and biofilms on surfaces is necessary to understand the biofilm formation and the social interactions between bacterial communities, which could provide useful hints to study the biofilm-involved diseases. Here patterned lubricant-infused surfaces (pLIS) are utilized to fabricate connective structures named "bacterial bridges" between bacterial colonies of Pseudomonas aeruginosa by a simple dewetting method. It is demonstrated that the bacteria attached to hydrophilic areas and bacteria precipitated on lubricant infused borders both contribute to the formation of bacterial bridges. The geometry and distribution of bridges can be controlled using predesigned superhydrophobic-hydrophilic patterns. It is demonstrated that bacterial bridges connecting bacteria colonies act as bio-microfluidic channels and can transport liquids, nutrients, and antibacterial substances between neighboring bacteria clusters. Thus, bacterial bridges can be used to study formation, spreading, and development of bacterial colonies, and communication within and between isolated biofilms.

Physico-chemical characterization and antimicrobial activity of an essential oil from the flowering umbels of wild Daucus carota L. subsp. carota growing in Algeria

ABSTRACT Aromatic and medicinal plants are an important source of molecules with antimicrobial effects, particularly in their volatile extracts. Species of the genus Daucus are considered among the richest plants in secondary metabolites, such as essential oils, which have an inhibitory effect on the development of bacterial colonies and harmful strains of fungi. Aiming at enhancing use of native plants in Algeria, we investigated essential oil from the flowering umbels of Daucus carota subsp. carota harvested in the region of Aith Laaziz (Algeria). Hydro-distillates were tested for their antimicrobial activities on bacteria and yeasts pathogenic to humans. The extraction produced a high yield of 3.65% essential oil. Analysis of the essential oil by GC (FID) and GC/MS allowed the identification of 47 compounds, four of which were predominant, represented by 53.4% of sesquiterpenes, carotol (10.38%), germacene D (9%). These secondary metabolites were shown to have moderate antimicrobial activity against B. subtilis and S. aureus , and yeast strains ( C. albicans and S. cerevisiae) . However, it should be noted that the MIC values are quite low (0.125-0.5%) but MBC and MFC values are average (0.5-1%).The essential oil is not very active against Gram - bacteria E.coli, P. aeruginosa and P. fluoresces where the MIC values are low (0.5 to 1%).

MODELING THE POPULATION DYNAMICS OF ANTIBIOTIC-RESISTANT BACTERIA: AN AGENT-BASED APPROACH

The response of bacterial populations to antibiotic treatment is often a function of a diverse range of interacting factors. In order to develop strategies to minimize the spread of antibiotic resistance in pathogenic bacteria, a sound theoretical understanding of the systems of interactions taking place within a colony must be developed. The agent-based approach to modeling bacterial populations is a useful tool for relating data obtained at the molecular and cellular level with the overall population dynamics. Here we demonstrate an agent-based model, called Micro-Gen, which has been developed to simulate the growth and development of bacterial colonies in culture. The model also incorporates biochemical rules and parameters describing the kinetic interactions of bacterial cells with antibiotic molecules.Simulations were carried out to replicate the development of methicillin-resistant S. aureus (MRSA) colonies growing in the presence of antibiotics. The model was explored to see how the properties of the system emerge from the interactions of the individual bacterial agents in order to achieve a better mechanistic understanding of the population dynamics taking place. Micro-Gen provides a good theoretical framework for investigating the effects of local environmental conditions and cellular properties on the response of bacterial populations to antibiotic exposure in the context of a simulated environment.

Distribution and development of bacterial colonies in fermented sausages

For fermented sausages the growth of microorganisms is essential for stable and safe products. It is important to note that the natural flora as well as added starter cultures are not evenly distributed in the interior of fermented sausages, but are immobilised in cavities or nests within the sausage matrix. A fact which must be taken into account when investigating growth kinetics and metabolism of, and interactions between, microorganisms during sausage fermentation. The distance between these nests of ripening flora varies from 100 to 5000 μm. If the properties of a sausage are changing during the ripening process in the desired direction (nitrate reduction, lactic acid production, catalase activity, etc.), then “large void areas”; of the sausage matrix between these cavities must be influenced by the bacteria growing in the nests. The latter are in keen competition. Therefore, after some time, due to accumulation of metabolic products and depletion of nutrients, bacterial growth ceases and cell divisi...

Allelopathic effects of Aristida adscensionis.

Investigations were carried out to study the allelopathic potentialities of Aristida adscensionis Linn.Bacterial culture experiments conducted have revealed that extracts of root, shoot and litter bring about a significant inhibition on the development of bacterial colonies of Azotobacter. When soil samples have been treated with these extracts, the soil nitrogen level has been diminished significantly in the soil samples treated with root extract, whereas with shoot extract the reduction in the soil nitrogen level was not significant. With litter leachate the depletion is found to be statistically significant at the 5% level.Thus it is concluded that Aristida adscensionis inhibits nitrogen fixing bacteria and thus creates a depleted nitrogen content in the soil. It is fairly probable that this may be a mechanism by which the species avoids competition from other species requiring good amounts of soil nitrogen for their metabolism. These results provide a possible explanation for the dominance of this grass species in the abandoned fields at Rajkot.