Characterizing A21: Natural Cyanobacteria-Based Consortium with Potential for Steroid Bioremediation in Wastewater Treatment.

Microalga-bacteria consortia are increasingly recognized for their effectiveness in wastewater treatment, leveraging the metabolic synergy between microalgae and bacteria to enhance nutrient removal and overall treatment efficiency. These systems offer a sustainable approach to addressing pollutants such as nitrogen and phosphorus. However, their potential in removing specific contaminants like steroid hormones is less explored.

Isolation and assessment of highly sucrose-tolerant yeast strains for honey processing factory's effluent treatment.

Wastewater from many food and beverage manufacturers is enriched in organic content, and it must therefore be treated before being discharged to comply with the strict environmental regulations to protect the final water quality. Concretely, the honey processing wastewater, that remains in holding tanks until is disposal, is a rich source of sugars and this high level of organic material will degrade the water quality if not treated properly provoking an imbalance in the ecosystem. There are different strategies for an adequate treatment of this wastewater effluent to obtain a sustainable usage.

Characterization of Limnospira platensis PCC 9108 R-M and CRISPR-Cas systems.

The filamentous cyanobacterium Limnospira platensis, formerly known as Arthrospira platensis or spirulina, is one of the most commercially important species of microalgae. Due to its high nutritional value, pharmacological and industrial applications it is extensively cultivated on a large commercial scale. Despite its widespread use, its precise manipulation is still under development due to the lack of effective genetic protocols.

First characterization of cultivable extremophile isolates from a solar panel.

Introduction: Microorganisms colonize a wide range of natural and artificial environments. Even though most of them are unculturable in laboratory conditions, some ecosystems are ideal niches for bioprospecting extremophiles with unique properties. Up today, there are few reports concerning microbial communities found on solar panels, a widespread, artificial, extreme habitat.

SEVA-Cpf1, a CRISPR-Cas12a vector for genome editing in cyanobacteria.

Background: Cyanobacteria are photosynthetic autotrophs that have tremendous potential for fundamental research and industrial applications due to their high metabolic plasticity and ability to grow using CO and sunlight. CRISPR technology using Cas9 and Cpf1 has been applied to different cyanobacteria for genome manipulations and metabolic engineering. Despite significant advances with genome editing in several cyanobacteria strains, the lack of proper genetic toolboxes is still a limiting factor compared to other model laboratory species.

Xerotolerance: A New Property in Genus.

The highly xerotolerant bacterium classified as sp. Helios isolated from a solar panel in Spain showed a close relationship to 255-15 isolated from Siberian permafrost. Xerotolerance has not been previously described as a characteristic of the extremely diverse genus, but both strains Helios and 255-15 showed higher xerotolerance than that described in the reference xerotolerant model strain  .

Further Studies on the 3-Ketosteroid 9α-Hydroxylase of Chol-4, a Rieske Oxygenase of the Steroid Degradation Pathway.

The biochemistry and genetics of the bacterial steroid catabolism have been extensively studied during the last years and their findings have been essential to the development of biotechnological applications. For instance, metabolic engineering of the steroid-eater strains has allowed to obtain intermediaries of industrial value. However, there are still some drawbacks that must be overcome, such as the redundancy of the steroid catabolism genes in the genome and a better knowledge of its genetic regulation.

Metabolic engineering of Rhodococcus ruber Chol-4: A cell factory for testosterone production.

Rhodococcus ruber Chol-4 is a potent steroid degrader that has a great potential as a biotechnological tool. As proof of concept, this work presents testosterone production from 4-androstene-3,17-dione by tailoring innate catabolic enzymes of the steroid catabolism inside the strain. A R.

New insights into the genome of Rhodococcus ruber strain Chol-4.

Background: Rhodococcus ruber strain Chol-4, a strain isolated from a sewage sludge sample, is able to grow in minimal medium supplemented with several compounds, showing a broad catabolic capacity. We have previously determined its genome sequence but a more comprehensive study of their metabolic capacities was necessary to fully unravel its potential for biotechnological applications.

Results: In this work, the genome of R.

Analysis of Intermediates of Steroid Transformations in Resting Cells by Thin-Layer Chromatography (TLC).

Thin-layer chromatography (TLC) is a useful and convenient method for the analysis of steroids due to: its simple sample preparation, low time-consuming process, high sensitivity, low equipment investment and capacity to work on many samples simultaneously. Here we describe a TLC easy protocol very useful to analyze steroid molecules derived from a biotransformation carried out in wild-type and mutant resting cells of Rhodococcus ruber strain Chol-4. Following this protocol, we were able to detect the presence or the absence of some well-known intermediates of cholesterol catabolism in Rhodococcus, namely AD, ADD, and 9OHAD.

Functional characterization of 3-ketosteroid 9α-hydroxylases in Rhodococcus ruber strain chol-4.

The 3-Ketosteroid-9α-Hydroxylase, also known as KshAB [androsta-1,4-diene-3,17-dione, NADH:oxygen oxidoreductase (9α-hydroxylating); EC 1.14.13.

Functional differentiation of 3-ketosteroid Δ-dehydrogenase isozymes in Rhodococcus ruber strain Chol-4.

Background: The Rhodococcus ruber strain Chol-4 genome contains at least three putative 3-ketosteroid Δ-dehydrogenase ORFs (kstD1, kstD2 and kstD3) that code for flavoenzymes involved in the steroid ring degradation. The aim of this work is the functional characterization of these enzymes prior to the developing of different biotechnological applications.

Results: The three R.

Cholesterol to cholestenone oxidation by ChoG, the main extracellular cholesterol oxidase of Rhodococcus ruber strain Chol-4.

The choG ORF of Rhodococcus ruber strain Chol-4 (referred from now as Chol-4) encodes a putative extracellular cholesterol oxidase. In the Chol-4 genome this ORF is located in a gene cluster that includes kstD3 and hsd4B, showing the same genomic context as that found in other Rhodococcus species. The putative ChoG protein is grouped into the class II of cholesterol oxidases, close to the Rhodococcus sp.

Draft Genome Sequence of the Steroid Degrader Rhodococcus ruber Strain Chol-4.

The whole-genome shotgun sequence of Rhodococcus ruber strain Chol-4 is presented here. This organism was shown to be able to grow using many steroids as the sole carbon and energy sources. These sequence data will help us to further explore the metabolic abilities of this versatile degrader.

Molecular characterization of three 3-ketosteroid-Δ(1)-dehydrogenase isoenzymes of Rhodococcus ruber strain Chol-4.

Rhodococcus ruber strain Chol-4 isolated from a sewage sludge sample is able to grow on minimal medium supplemented with steroids, showing a broad catabolic capacity. This paper reports the characterization of three different 3-ketosteroid-Δ(1)-dehydrogenases (KstDs) in the genome of R. ruber strain Chol-4.

ChoG is the main inducible extracellular cholesterol oxidase of Rhodococcus sp. strain CECT3014.

Cholesterol catabolism has been reported in different bacteria and particularly in several Rhodococcus species, but the genetic of this complex pathway is not yet very well defined. In this work we report the isolation and sequencing of a 9.8 kb DNA fragment of Rhodococcus sp.

Stationary phase in gram-negative bacteria.

Conditions that sustain constant bacterial growth are seldom found in nature. Oligotrophic environments and competition among microorganisms force bacteria to be able to adapt quickly to rough and changing situations. A particular lifestyle composed of continuous cycles of growth and starvation is commonly referred to as feast and famine.

Genetic analysis of phenylacetic acid catabolism in Arthrobacter oxydans CECT386.

Arthrobacter oxydans CECT386 is a Gram-positive bacterium able to use either phenylacetic acid or phenylacetaldehyde as the sole carbon and energy source for aerobic growth. Genes responsible for the catabolism of these compounds have been located at two chromosomal regions and were organized in one isolated paaN gene and two putative paa operons, one consisting of the paaD, paaF, tetR and prot genes, and one consisting of the paaG, paaH, paaI, paaJ, paaK and paaB genes. The identity of the paaF and paaN genes was supported by functional complementation experiments.

Two interaction sites on mammalian adenylyl cyclase type I and II: modulation by calmodulin and G(betagamma).

Mammalian ACs (adenylyl cyclases) are integrating effector molecules in signal transduction regulated by a plethora of molecules in either an additive, synergistic or antagonistic manner. Out of nine different isoforms, each AC subtype uses an individual set of regulators. In the present study, we have used chimaeric constructs, point mutations and peptide competition studies with ACs to show a common mechanism of multiple contact sites for the regulatory molecules G(betagamma) and calmodulin.

Phenylacetate catabolism in Rhodococcus sp. strain RHA1: a central pathway for degradation of aromatic compounds.

In gram-negative bacteria, a pathway for aerobic degradation of phenylacetic acid (PAA) that proceeds via phenylacetyl-coenzyme A (CoA) and hydrolytic ring fission plays a central role in the degradation of a range of aromatic compounds. In contrast, the PAA pathway and its role are not well characterized in gram-positive bacteria. A cluster including 13 paa genes encoding enzymes orthologous to those of gram-negative bacteria was identified on the chromosome of Rhodococcus sp.

GASP phenotype: presence in enterobacteria and independence of sigmaS in its acquisition.

The appearance of growth advantage in stationary phase or GASP was originally detected in Escherichia coli. The presence of this phenotype in other enterobacteria such as Enterobacter cloacae, Salmonella typhimurium, Providencia stuartii and Shigella dysenteriae is described in this work. E.

Polymorphism in the yclC-rpoS region of enterobacteria.

The nucleotide sequence downstream from the rpoS gene in Enterobacter cloacae and Kluyvera cryocrescens contains the slyA-pad1-yclC genes. The DNA sequence of Enterobacter cloacae CETC960 shows a 2.6-kb insertion of unknown origin between rpoS and slyA.

Construction of a bacterial biosensor for styrene.

A new bacterial biosensor for styrene has been developed and characterized. A translational fusion of the lacZ gene to the sty promoter of Pseudomonas sp. strain Y2 has been inserted into miniTn5.

Identification of an unknown promoter, OUTIIp, within the IS10R element.

A novel promoter in IS10R (OUTIIp) has been found in one of its ends in an inverted position relative to promoter pOUT. OUTIIp shows characteristics similar to those of rpoS-dependent promoters such as a gearbox expression pattern. It is under catabolite repression and positively regulated by ppGpp or conditioned media.

Enterobacter cloacae rpoS promoter and gene organization.

The upstream region of the Enterobacter cloacae strain CECT960 rpoS gene was sequenced. An IS 10R element was found within the nlpD gene, between rpoSp and rpoS. The rpoS promoter, although functional, did not drive transcription of the gene in this strain.