Archiv für Mikrobiologie

Biodegradation is the most promising environmentally sustainable method that offers a significant opportunity with minimal negative environmental consequences while searching for solutions to this global problem of plastic pollution that has now spread to almost everywhere in the entire world. In the present work, HDPE-degrading bacterial strain CGK112 was isolated from the fecal matter of a cow. The bacterial strain was identified as Micrococcus luteus CGK112 by 16S rRNA sequence coding analysis. Significant weight loss, i.e., 3.85% was recorded in the HDPE film treated with strain CGK112 for 90 days. The surface micromorphology was examined using FE-SEM, which revealed spectacular bacterial colonization as well as structural deformation. Furthermore, the EDX study indicated a significant decrease in the atomic percentage of carbon content, whereas FTIR analysis confirmed functional groups alternation as well as an increase in the carbonyl index which can be attributed to the metabolic activity of biofilm. Our findings provide insight into the capacity of our strain CGK112 to colonize and utilize HDPE as a single carbon source, thus promoting its degradation.

Biofilm-mediated multidrug resistance has turned into major challenge for the treatment of C. albicans infections. In the present study, actinomycetes (SS5) isolated from marine crustacean were investigated for their ability to inhibit C. albicans biofilm formation. Cultural, morphological and 16S rRNA analysis revealed that the isolated strain was Streptomyces diastaticus. Ethyl acetate bioactive fractions (6 µg mL−1) from SS5 showed potent antibiofilm activity against C. albicans. Light microscopic and CLSM analysis further substantiated the antibiofilm activity of the bioactive fraction against C. albicans. The bioactive fraction was subjected to FTIR and GC–MS for characterization. From GC–MS analysis, the presence of 31 compounds were revealed, among which the alkanes are predominantly present. Hence, further investigation for the potential of these bioactive compounds against C. albicans biofilm will help in the identification of promising candidate for the prevention of biofilm-mediated infection.

Twin-arginine targeting (Tat) protein secretion systems consist of two protein types, members of the TatA and TatC families. Homologues of these proteins are found in many archaea, bacteria, chloroplasts and mitochondria. Every prokaryotic organism with a fully sequenced genome exhibits either neither family member, or between one and three paralogues of these two family members. The Arabidopsis thaliana genome encodes three of each. Although many mitochondrially encoded TatC homologues have been identified, corresponding TatA homologues have not been found in this organelle. Phylogenetic analyses reveal that most prokaryotic Tat systems consist of one TatC homologue and two sequence-divergent TatA homologues (TatA and TatB). When only one TatA homologue is present, TatB is missing, and when three TatA homologues are present, the third one arose by duplication of TatA, not TatB. Further, homologues most resembling TatB are more sequence-divergent than those more closely resembling TatA. In contrast to the TatA family, the TatC family shows phylogenetic clustering in strict accordance with organismal type. These results are discussed in terms of their probable structural, functional and evolutionary significance.

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Diagnosis of bacterial infections (BI) is becoming an increasingly difficult task in clinical practice due to their high prevalence and frequency, as well as the growth of antibiotic resistance worldwide. World Health Organization (WHO) reported antibiotic resistance is a major public health problem. BI becomes difficult or impossible to treat when the bacteria acquire immunity against antibiotics. Thus, there is a need for a quick and accurate technique to detect infection. Lateral flow immunoassay (LFIA) is an ideal technique for point-of-care testing of a disease or pathological changes inside the human body. In recent years, several LFIA based strips are being used for the detection of BI by targeting specific analytes which may range from the causative bacterium, whole-cell, DNA, or biomarker. Numerous nanoparticles like lipid-based nanoparticles, polymeric nanoparticles, and inorganic nanoparticles such as quantum dots, magnetic, ceramic, and metallic nanoparticles (copper, silver gold, iron) are widely being used in the advanced treatment of BI. Out of these gold nanoparticle (AuNPs), is being used for detection BI more effectively than other nanoparticles due to their surface functionalization, extraordinary chemical stability, biorecognition, and signal amplification properties and help to improve in conjugation with capture antibodies, and act as a color marker with unique optical properties on LFIA strips. Herein, a review that provides an overview of the principle of LFIA, how LFIA based strip is developed, and how it is helpful to detect a specific biomarker for bedside detection of the BI.

Endogenous and maximum respiration rates of nine purple sulfur bacterial strains were determined. Endogenous rates were below 10 nmol O2 · (mg protein · min)-1 for sulfur-free cells and 15–35 nmol O2 · (mg protein · min)-1 for cells containg intracellular sulfur globules. With sulfide as electron-donating substrate respiration rates were considerably higher than with thiosulfate. Maximum respiration rates of Thiocystis violacea 2711 and Thiorhodovibrio winogradskyi SSP1 (254.8 and 264.2 nmol O2 · (mg protein · min)-1, respectively) are similar to those of aerobic bacteria. Biphasic respiration curves were obtained for sulfur-free cells of Thiocystis violacea 2711 and Chromatium vinosum 2811. In Thiocystis violacea the rapid and incomplete oxidation of thiosulfate was five times faster than the oxidation of stored sulfur. A high affinity of the respiratoty system for oxygen (K m =0.3–0.9 μM O2, V max=260 nmol O2 · (mg protein · min)-1 with sulfide as substrate, K m =0.6–2.4 μM O2, V max=14–40 nmol O2 · (mg protein · min)-1 with thiosulfate as substrate), for sulfide (K m =0.47 μM, V max=650 nmol H2S · (mg protein × min)-1, and for thiosulfate (K m =5–6 μM, V max =24–72 nmol S2O 3 2- · (mg protein · min)-1 was obtained for different strains. Respiration of Thiocystis violacea was inhibited by very low concentrations of NaCN (K i =1.7 μM) while CO concentrations of up to 300 μM were not inhibitory. The capacity for chemotrophic growth of six species was studied in continuous culture at oxygen concentrations of 11 to 67 μM. Thiocystis violacea 2711, Amoebobacter roseus 6611, Thiocapsa roseopersicina 6311 and Thiorhodovibrio winogradskyi SSP1 were able to grow chemotrophically with thiosulfate/acetate or sulfide/acetate. Chromatium vinosum 2811 and Amoebobacter purpureus ML1 failed to grow under these conditions. During shift from phototrophic to chemotrophic conditions intracellular sulfur and carbohydrate accumulated transiently inside the cells. During chemotrophic growth bacteriochlorophyll a was below the detection limit.

Cellulosimicrobium strain SE3T was isolated from the San Elijo coastal lagoon near San Diego. A whole genome-based phylogenetic comparison shows great heterogeneity within the Cellulosimicrobium genus. Based on average nucleotide identity, whole genome-based comparison, and the presence of a unique l-fucose metabolic pathway, strain SE3T was shown to belong to a novel species within the genus, together with five other strains. The name Cellulosimicrobium fucosivorans sp. nov. is proposed, with strain SE3T as the type strain. The strain encodes a unique alpha-l-fucosidase and the l-fucose metabolic pathway is homologous to the one recently described in Campylobacter jejuni. C. fucosivorans is able to grow on l-fucose, and interestingly, the biosynthesis of the yellow carotenoid is dependent on the presence of l-fucose in the media. The ability to metabolize fucose and the linked production of carotenoids are expected to provide C. fucosivorans with a competitive advantage in the sunny coastal lagoon area.

Pentachlorophenol (PCP) is a toxic compound, which is widely used as a wood preservative product and general biocide. It is persistent in the environment and has been classified as a persistent organic pollutant to be reclaimed in many countries. Bioremediation is an emerging approach to rehabilitating areas polluted by recalcitrant xenobiotics. In the present study, we evaluated the potential of three strains of Pseudomonas (P. putida S121, P. rhizophila S211, and P. fuscovagiceae S115) as bioremediation agents in depletion and detoxification of PCP in soil microcosms. PCP removal was effectively optimized using a central-composite experimental design and response surface methodology (RSM). The optimum conditions for maximum PCP removal yield (85 ± 5%) were: 500 mg/kg PCP concentration, 108 UFC/g soil inoculum size of each strain and 55 days incubation period. The bacterial strains, P. putida, P. rhizophila, and P. fuscovagiceae, showed good capability to tolerate and degrade PCP so that they could be successfully used in synergistic effect to treat PCP polluted soils.