Amycolatopsis vastitatis sp. nov., an isolate from a high altitude subsurface soil on Cerro Chajnantor, northern Chile.

The taxonomic position of a novel Amycolatopsis strain isolated from a high altitude Atacama Desert subsurface soil was established using a polyphasic approach. The strain, isolate H5T, was shown to have chemical properties typical of members of the genus Amycolatopsis such as meso-diaminopimelic acid as the diamino acid in the cell wall peptidoglycan, arabinose and galactose as diagnostic sugars and MK-9(H4) as the predominant isoprenologue. It also has cultural and morphological properties consistent with its classification in the genus, notably the formation of branching substrate hyphae which fragment into rod-like elements. 16S rRNA gene sequence analyses showed that the strain is closely related to the type strain of Amycolatopsis mediterranei but could be distinguished from this and other related Amycolatopsis strains using a broad range of phenotypic properties. It was separated readily from the type strain of Amycolatopsis balhymycina, its near phylogenetic neighbour, based on multi-locus sequence data, by low average nucleotide identity (92.9%) and in silico DNA/DNA relatedness values (51.3%) calculated from draft genome assemblies. Consequently, the strain is considered to represent a novel species of Amycolatopsis for which the name Amycolatopsis vastitatis sp. nov. is proposed. The type strain is H5T (= NCIMB 14970T = NRRL B-65279T).

Cellulosimicrobium marinum sp. nov., an actinobacterium isolated from sea sediment.

A novel Gram stain positive actinobacterium, designated RS-7-4(T), was isolated from a sea sediment sample collected in Indonesia, and its taxonomic position was investigated using a polyphasic approach. Strain RS-7-4(T) was observed to form vegetative hyphae in the early phase of growth, but the hyphae eventually fragmented into short rods to coccoid cells. Growth occurred at 15-37 °C, pH 6.0-11.0 and in the presence of 0-7 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain RS-7-4(T) was closely related to the members of the genus Cellulosimicrobium, with a similarity range of 98.08-99.10 %. The peptidoglycan type of strain RS-7-4(T) was found to be A4α L-Lys-L-Thr-D-Asp. The predominant menaquinone was MK-9(H4), and the major fatty acids were anteiso-C15:0, iso-C15:0 and anteiso-C17:0. The DNA G+C content was 75.6 mol%. These chemotaxonomic features corresponded to those of the genus Cellulosimicrobium. Meanwhile, the results of DNA-DNA hybridization, and physiological and biochemical tests revealed that strain RS-7-4(T) was different from the recognized species of the genus Cellulosimicrobium. Therefore, strain RS-7-4(T) represents a novel species of the genus Cellulosimicrobium, for which the name Cellulosimicrobium marinum sp. nov. is proposed. The type strain is RS-7-4(T) (=NBRC 110994(T) =InaCC A726(T)).

Aeromicrobium halotolerans sp. nov., isolated from desert soil sample.

A Gram-positive, aerobic, and non-motile, rod-shaped actinomycete strain, designated YIM Y47(T), was isolated from soils collected from Turpan desert, China, and subjected to a polyphasic taxonomic study. Phylogenetic analysis indicated that strain YIM Y47(T) belonged to the genus Aeromicrobium. YIM Y47(T) shared highest 16S rRNA gene sequence similarities with Aeromicrobium massiliense JC14(T) (96.47 %). Growth occurs at 20-45 °C (optimum at 30 °C), pH 6.0-8.0 (optimum at pH 7.0), and salinities of 0-7.0 % NaCl (optimum at 4.0 %). The strain YIM Y47(T) exhibits chemotaxonomic features with menaquinone-7 (MK-7) as the predominant quinone, C16:0, C18:1 ω9c and 10-methyl C18:0 (>10 %) as major fatty acids. The cell-wall peptidoglycan of strain YIM Y47(T) contained LL-diaminopimelic acid as the diagnostic diamino acid. The polar lipids were found to consist of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, and unknown phospholipids. The G+C content of the genomic DNA of strain YIM Y47(T) was found to be 44.7 mol%. On the basis of phylogenetic analyses and phenotypic data, it is proposed that strain YIM Y47(T) should be classified as representing a novel species of the genus Aeromicrobium, with the name Aeromicrobium halotolerans sp. nov. The type strain is YIM Y47(T) (=KCTC 39113(T)=CGMCC 1.15063(T)=DSM 29939(T)=JCM 30627(T)).

Differential immune responses to Segniliparus rotundus and Segniliparus rugosus infection and analysis of their comparative virulence profiles.

Two closely related bacterial species, Segniliparus rotundus and Segniliparus rugosus, have emerged as important human pathogens, but little is known about the immune responses they elicit or their comparative pathophysiologies. To determine the virulence and immune responses of the two species, we compared their abilities to grow in phagocytic and non-phagocytic cells. Both species maintained non-replicating states within A549 epithelial cells. S. rugosus persisted longer and multiplied more rapidly inside murine bone marrow-derived macrophages (BMDMs), induced more pro-inflammatory cytokines, and induced higher levels of macrophage necrosis. Activation of BMDMs by both species was mediated by toll-like receptor 2 (TLR2), followed by mitogen-activated protein kinases (MAPK) and nuclear factor κB (NF-κB) signaling pathways, indicating a critical role for TLR2 in Segniliparus-induced macrophage activation. S. rugosus triggered faster and stronger activation of MAPK signaling and IκB degradation, indicating that S. rugosus induces more pro-inflammatory cytokines than S. rotundus. Multifocal granulomatous inflammations in the liver and lung were observed in mice infected with S. rugosus, but S. rotundus was rapidly cleared from all organs tested within 15 days post-infection. Furthermore, S. rugosus induced faster infiltration of innate immune cells such as neutrophils and macrophages to the lung than S. rotundus. Our results suggest that S. rugosus is more virulent and induces a stronger immune response than S. rotundus.

Actinopolyspora saharensis sp. nov., a novel halophilic actinomycete isolated from a Saharan soil of Algeria.

A novel halophilic actinomycete, strain H32(T), was isolated from a Saharan soil sample collected in El-Oued province, south Algeria. The isolate was characterized by means of polyphasic taxonomy. Optimal growth was determined to occur at 28-32 °C, pH 6.0-7.0 and in the presence of 15-25 % (w/v) NaCl. The strain was observed to produce abundant aerial mycelium, which formed long chains of rod-shaped spores at maturity, and fragmented substrate mycelium. The cell wall was determined to contain meso-diaminopimelic acid and the characteristic whole-cell sugars were arabinose and galactose. The predominant menaquinones were found to be MK-10(H4) and MK-9(H4). The predominant cellular fatty acids were determined to be anteiso C17:0, iso-C15:0 and iso-C16:0. The diagnostic phospholipid detected was phosphatidylcholine. Phylogenetic analyses based on the 16S rRNA gene sequence showed that this strain formed a distinct phyletic line within the radiation of the genus Actinopolyspora. The 16S rRNA gene sequence similarity indicated that strain H32(T) was most closely related to 'Actinopolyspora algeriensis' DSM 45476(T) (98.8 %) and Actinopolyspora halophila DSM 43834(T) (98.5 %). Furthermore, the result of DNA-DNA hybridization between strain H32(T) and the type strains 'A. algeriensis' DSM 45476(T), A. halophila DSM 43834(T) and Actinopolyspora mortivallis DSM 44261(T) demonstrated that this isolate represents a different genomic species in the genus Actinopolyspora. Moreover, the physiological and biochemical data allowed the differentiation of strain H32(T) from its closest phylogenetic neighbours. Therefore, it is proposed that strain H32(T) represents a novel species of the genus Actinopolyspora, for which the name Actinopolyspora saharensis sp. nov. is proposed. The type strain is H32(T) (=DSM 45459(T)=CCUG 62966(T)).

Transcriptional profiling of genes involved in n-hexadecane compounds assimilation in the hydrocarbon degrading Dietzia cinnamea P4 strain

The petroleum-derived degrading Dietzia cinnamea strain P4 recently had its genome sequenced and annotated. This allowed employing the data on genes that are involved in the degradation of n-alkanes. To examine the physiological behavior of strain P4 in the presence of n-alkanes, the strain was grown under varying conditions of pH and temperature. D. cinnamea P4 was able to grow at pH 7.0-9.0 and at temperatures ranging from 35 ºC to 45 ºC. Experiments of gene expression by real-time quantitative RT-PCR throughout the complete growth cycle clearly indicated the induction of the regulatory gene alkU (TetR family) during early growth. During the logarithmic phase, a large increase in transcriptional levels of a lipid transporter gene was noted. Also, the expression of a gene that encodes the protein fused rubredoxin-alkane monooxygenase was enhanced. Both genes are probably under the influence of the AlkU regulator.

Interspecies modulation of bacterial development through iron competition and siderophore piracy.

While soil-dwelling actinomycetes are renowned for secreting natural products, little is known about the roles of these molecules in mediating actinomycete interactions. In a previous co-culture screen, we found that one actinomycete, Amycolatopsis sp. AA4, inhibited aerial hyphae formation in adjacent colonies of Streptomyces coelicolor. A siderophore, amychelin, mediated this developmental arrest. Here we present genetic evidence that confirms the role of the amc locus in the production of amychelin and in the inhibition of S. coelicolor development. We further characterize the Amycolatopsis sp. AA4 - S. coelicolor interaction by examining expression of developmental and iron acquisition genes over time in co-culture. Manipulation of iron availability and/or growth near Amycolatopsis sp. AA4 led to alterations in expression of the critical developmental gene bldN, and other key downstream genes in the S. coelicolor transcriptional cascade. In Amycolatopsis sp. AA4, siderophore genes were downregulated when grown near S. coelicolor, leading us to find that deferrioxamine E, produced by S. coelicolor, could be readily utilized by Amycolatopsis sp. AA4. Collectively these results suggest that competition for iron via siderophore piracy and species-specific siderophores can alter patterns of gene expression and morphological differentiation during actinomycete interactions.

Microbial selection on enhanced biological phosphorus removal systems fed exclusively with glucose.

The microbial selection on an enhanced biological phosphorus removal (EBPR) system was investigated in a laboratory-scale sequencing batch reactor fed exclusively with glucose as the carbon source. Fluorescence In Situ Hybridization analysis was performed to target two polyphosphate accumulating organisms (PAOs) (i.e., Candidatus Accumulibacter phosphatis and Microlunatus phosphovorus) and two glycogen accumulating organisms (GAOs) (i.e., Candidatus Competibacter phosphatis and Micropruina glycogenica). The results show that glucose might not select for Candidatus Accumulibacter phosphatis. However, Microlunatus phosphovorus, Candidatus Competibacter phosphatis, and Micropruina glycogenica might be selected. The highest percent relative abundance (% RA) of Candidatus Accumulibacter phosphatis was about 42%; this occurred at the beginning of the experimental period when phosphorus removal was efficient. However, the % RA of these bacteria decreased, reaching below 4% at the end of the run. The maximum % RA of Microlunatus phosphovorus, Candidatus Competibacter phosphatis, and Micropruina glycogenica was about 21, 37, 17%, respectively. It appears that a higher glucose concentration might be detrimental for Microlunatus phosphovorus and Micropruina glycogenica. Results also indicate a dominance of GAOs over PAOs when EBPR systems are fed with glucose. It is possible that the GAOs outcompete the PAOs at low pH values; it has been reported that at low pH, GAOs use glycogen as the energy source to uptake glucose. As a result, P-removal deteriorated. Therefore, glucose is not a strong candidate as a carbon source to supplement EBPR systems that do not contain sufficient volatile fatty acids.

Insight from the draft genome of Dietzia cinnamea P4 reveals mechanisms of survival in complex tropical soil habitats and biotechnology potential.

The draft genome of Dietzia cinnamea strain P4 was determined using pyrosequencing. In total, 428 supercontigs were obtained and analyzed. We here describe and interpret the main features of the draft genome. The genome contained a total of 3,555,295 bp, arranged in a single replicon with an average G+C percentage of 70.9%. It revealed the presence of complete pathways for basically all central metabolic routes. Also present were complete sets of genes for the glyoxalate and reductive carboxylate cycles. Autotrophic growth was suggested to occur by the presence of genes for aerobic CO oxidation, formate/formaldehyde oxidation, the reverse tricarboxylic acid cycle and the 3-hydropropionate cycle for CO(2) fixation. Secondary metabolism was evidenced by the presence of genes for the biosynthesis of terpene compounds, frenolicin, nanaomycin and avilamycin A antibiotics. Furthermore, a probable role in azinomycin B synthesis, an important product with antitumor activity, was indicated. The complete alk operon for the degradation of n-alkanes was found to be present, as were clusters of genes for biphenyl ring dihydroxylation. This study brings new insights in the genetics and physiology of D. cinnamea P4, which is useful in biotechnology and bioremediation.

Enhanced production of ansamitocin P-3 by addition of Mg2+ in fermentation of Actinosynnema pretiosum.

The effect of divalent metal ions (i.e., Mn(2+), Mg(2+), Zn(2+), Cu(2+), and Co(2+)) on the production of anticancer ansamitocin P-3 (AP-3) by submerged cultures of Actinosynnema pretiosum in medium containing agro-industrial residues was investigated, and Mg(2+) was found to be the most effective. Under the optimal condition of Mg(2+) addition, the maximal AP-3 production titer reached 85 mg/L, which was 3.0-fold that of the control. The activities of methylmalonyl-CoA carboxyltransferase (MCT) and methylmalonyl-CoA mutase (MCM) were enhanced. The content of two precursors, malonyl-CoA and methylmalonyl-CoA, was lower than that of control. This work demonstrates that Mg(2+) addition is a simple and effective strategy for increasing AP-3 production through the regulation of enzyme activity and pools of precursors. The information obtained can be helpful to its efficient production on large scale.

Metabolic engineering of Thermobifida fusca for direct aerobic bioconversion of untreated lignocellulosic biomass to 1-propanol.

Biofuel production from renewable resources can potentially address lots of social, economic and environmental issues but an efficient production method has yet to be established. Combinations of different starting materials, organisms and target fuels have been explored with the conversion of cellulose to higher alcohols (1-propanol, 1-butanol) being one potential target. In this study we demonstrate the direct conversion of untreated plant biomass to 1-propanol in aerobic growth conditions using an engineered strain of the actinobacterium, Thermobifida fusca. Based upon computational predictions, a bifunctional butyraldehyde/alcohol dehydrogenase was added to T. fusca leading to 1-propanol production during growth on glucose, cellobiose, cellulose, switchgrass and corn stover. The highest 1-propanol titer (0.48g/L) was achieved for growth on switchgrass. These results represent the first demonstration of direct conversion of untreated lignocellulosic biomass to 1-propanol in an aerobic organism and illustrate the potential utility of T. fusca as an aerobic, cellulolytic bioprocess organism.

[Influence of microbial-epithelial interactions on biological characteristics of vaginal microflora].

AIM: Evaluation of influence of microbial epithelial interactions on growth properties and antagonistic activity of dominant and associated vaginal microflora. MATERIALS AND METHODS: Growth characteristics and antagonistic activity changes were studied in associated (Staphylococcus aureus, Escherichia coli, Corynebacterium spp.) and dominant (Lactobacilus spp.) microflora during contact with vaginal epitheliocytes and influence of vaginal epitheliocyte secretory products by using the developed technique. RESULTS: Secretory products of vaginal epitheliocytes and vaginal epitheliocytes differentially influence growth factors of vaginal microbiocenosis. Suppression of S. aureus and E. coli biomass growth based predominately on extracellular secretory products of epitheliocytes was observed. Stimulation of growth properties was prevalent for lactobacilli and corynebacteria and was observed in contact interaction as well as during effect of epitheliocyte extracellular secretory products. CONCLUSION: The resulting bacterial-epithelial interaction is a differentiating feature between autochthonous and allochthonous microflora due to the creation of selective advantages for dominant microsymbionts by growth properties and antagonistic activity stimulation, and biomass growth suppression of associated symbionts.

High diversity and abundance of putative polyphosphate-accumulating Tetrasphaera-related bacteria in activated sludge systems.

The diversity of the putative polyphosphate-accumulating genus Tetrasphaera in wastewater treatment systems with enhanced biological phosphorus removal (EBPR) was investigated using the full-cycle rRNA approach combined with microautoradiography and histochemical staining. 16S rRNA actinobacterial gene sequences were retrieved from different full-scale EBPR plants, and the sequences belonging to the genus Tetrasphaera (family Intrasporangiaceae) were found to form three clades. Quantitative FISH analyses of the communities in five full-scale EBPR plants using 10 new oligonucleotide probes were carried out. The results showed that the probe-defined Tetrasphaera displayed different morphologies and constituted up to 30% of the total biomass. It was shown that active uptake of orthophosphate and formation of polyphosphate took place in most of the probe-defined Tetrasphaera populations. However, aerobic uptake of orthophosphate only took place after uptake of certain carbon sources under anaerobic conditions and these were more diverse than hitherto assumed: amino acids, glucose, and for some also acetate. Tetrasphaera seemed to occupy a slightly different ecological niche compared with 'Candidatus Accumulibacter' contributing to a functional redundancy and stability of the EBPR process.

Pentose phosphate pathway flux analysis for glycopeptide antibiotic vancomycin production during glucose-limited cultivation of Amycolatopsis orientalis.

In vivo pentose phosphate pathway (PPP) enzymes such as glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), and transaldolase (TAL) activities as well as ATP- and ADP-level variations of Amycolatopsis orientalis were investigated with respect to glucose concentration and incubation period. G6PDH, 6PGDH, and TAL activities of A. orientalis reached maximum levels at 48 hr for all glucose concentrations used, after which the levels began to decline. G6PDH, 6PGDH, and TAL activities showed positive correlation with the glucose concentration up to 15 g/L, while further increases had an opposite effect. Intracellular ATP level showed a positive correlation with glucose concentrations, while ADP level increased up to 15 g/L. ATP concentration of A. orientalis increased rapidly at 48 hr of incubation, as was the case also for G6PDH, 6PGDH, and TAL activities, although the incubation period corresponding to maximum values of ADP shifted to 60 hr. Production of the glycopeptide antibiotic vancomycin increased with the increases in glucose concentrations up to 15 g/L, by showing coherence in the rates of oxidative and nonoxidative parts of the PPP.

Silencing of host basal defense response-related gene expression increases susceptibility of Nicotiana benthamiana to Clavibacter michiganensis subsp. michiganensis.

Clavibacter michiganensis subsp. michiganensis is an actinomycete, causing bacterial wilt and canker disease of tomato (Solanum lycopersicum). We used virus-induced gene silencing (VIGS) to identify genes playing a role in host basal defense response to C. michiganensis subsp. michiganensis infection using Nicotiana benthamiana as a model plant. A preliminary VIGS screen comprising 160 genes from tomato known to be involved in defense-related signaling identified a set of 14 genes whose suppression led to altered host-pathogen interactions. Expression of each of these genes and three additional targets was then suppressed in larger-scale VIGS experiments and the effect of silencing on development of wilt disease symptoms and bacterial growth during an N. benthamiana-C. michiganensis subsp. michiganensis compatible interaction was determined. Disease susceptibility and in planta bacterial population size were enhanced by silencing genes encoding N. benthamiana homologs of ubiquitin activating enzyme, snakin-2, extensin-like protein, divinyl ether synthase, 3-hydroxy-3-methylglutaryl-coenzyme A reductase 2, and Pto-like kinase. The identification of genes having a role in the host basal defense-response to C. michiganensis subsp. michiganensis advances our understanding of the plant responses activated by C. michiganensis subsp. michiganensis and raises possibilities for devising novel and effective molecular strategies to control bacterial canker and wilt in tomato.

Enhanced production of ansamitocin P-3 by addition of isobutanol in fermentation of Actinosynnema pretiosum.

Supply of isobutanol to enhance the production of anti-tumor agent ansamitocin P-3 (AP-3) in medium containing agro-industrial residues was investigated with analysis of gene transcription, enzyme activity, and intermediate accumulation. Under the optimal addition of isobutanol, about 4-fold improvement of AP-3 production was obtained, and the consumption of isobutanol and accumulation of isobutyrate, malonyl-CoA, and acetyl-CoA were observed. Compared to the control without isobutanol addition, activities of both isobutanol dehydrogenase and valine dehydrogenase were enhanced in isobutanol supplemented culture. Transcription level of genes in AP-3 biosynthetic and isobutyryl-CoA catabolic pathways responded to isobutanol addition in a similar way as AP-3 biosynthesis. It is concluded that isobutanol addition was an effective strategy for increasing AP-3 production via regulation of gene transcription and pools of precursors, and the information obtained might be helpful to the fermentation productivity improvement on large scale.

[Filamentous "contaminants" in the mycobacteriology laboratory; their culture, identification and clinical significance]. / Vlálmoté "kontaminanty" v mykobakteriologické laboratori, jejich kultivace, identifikace a klinický význam.

Frequent "contaminants" detected during mycobacterial culture of decontaminated samples are bacteria of the order Actinomycetales. These are usually bacteria classified as the family Corynebacterineae, genera Corynebacterium, Dietzia, Gordonia, Nocardia, Rhodococcus and Tsukamurella. These bacteria frequently colonize the airways and, under certain circumstances, they may cause life-threatening diseases. In severely immunocompromised patients, they regularly cause life-threatening infections with bacteria of the genus Nocardia. These filamentous bacteria, developing aerial mycelium in the culture, are partly acid-resistant and resistant to lysozyme. They cause nocardiosis, a rare but serious disease in patients with various types of immune deficiency. Differential diagnosis must distinguish between the genera Streptomyces, Actinomadura and Nocardiopsis and other soil saprophytes that are not acid-resistant, sensitive to lysozyme and faster growing. They frequently colonize the airways of patients with lung disease but very rarely cause diseases. The diagnosis of aerobic actinomycetes and determination of their sensitivity to antibiotics are problematic since they grow longer, are difficult to stain and are involved in atypical biochemical reactions. Precise identification of the genera and species requires polyphasic identification of isolates using molecular microbiology methods. If diagnosed early, infections caused by aerobic actinomycetes are easy to treat with targeted antibiotic therapy.

Influence of culture aeration on the cellulase activity of Thermobifida fusca.

Currently, one of the hurdles hindering efficient production of cellulosic biofuel is the recalcitrant nature of cellulose to hydrolysis. A wide variety of cellulase enzymes are found natively in microorganisms that can potentially be used to effectively hydrolyze cellulose to fermentable sugars. In this study, phenomenological and mechanistic parameters affecting cellulase activity were studied using the moderately thermophilic, aerobic, and cellulolytic microorganism Thermobifida fusca. Two major sets of experiments were conducted to (1) study the mechanistic differences in growth in a flask compared to a bioreactor and (2) study the cell culture parameters influencing cellulase activity using a series of bioreactor experiments. Specific cellulase and specific endoglucanase activities were found to be higher in the bioreactor as compared to flask growth. Measurements of messenger RNA transcript levels of 18 cellulase-related genes and intracellular ATP levels indicated that measured enzyme activity was likely more influenced by post-transcriptional energetics rather than transcriptional regulation. By delineating the effects of culture aeration and stir speed using a bioreactor, it was found that cellulase activity increased with increasing aeration and increasing stir speeds (highest K(l)a) with a tradeoff of decreased cellular growth at the highest stir speeds tested (400 rpm). Overall, these results allude to a connection between aeration and oxidative respiration that lead to increased ATP allowing for increased cellulase synthesis as the primary constraint on overall cellulase activity.

Expression of pyrrothine N-acyltransferase activities in Saccharothrix algeriensis NRRL B-24137: new insights into dithiolopyrrolone antibiotic biosynthetic pathway.

AIMS: The hypothetical dithiolopyrrolone biosynthetic pathway includes a final step of pyrrothine nucleus acylation. The presence of an enzymatic activity catalysing this reaction was investigated in Saccharothrix algeriensis NRRL B-24137. To understand the effect exerted by organic acids on the level of dithiolopyrrolone production, their influence on enzymatic expression was studied. METHODS AND RESULTS: The transfer of acetyl-CoA or benzoyl-CoA on pyrrothine was assayed in the cell-free extract of Sa. algeriensis NRRL B-24137. This study reports the presence of an enzymatic activity catalysing this reaction that was identified as either pyrrothine N-acetyltransferase or N-benzoyltransferase. The stimulation of benzoyl-pyrrothine (BEP) production by addition of benzoic acid at 1.25 mmol l(-1) into the culture medium was demonstrated, and results showed that under the same conditions of growth, pyrrothine N-benzoyltransferase specific activity was doubled. CONCLUSIONS: This study shows that BEP production is enhanced in the presence of benzoic acid partly because of an induction of pyrrothine N-benzoyltransferase. SIGNIFICANCE AND IMPACT OF THE STUDY: The antitumor and antibiotic properties of dithiolopyrrolones are related to their variable acyl groups. New insights into regulation of biosynthetic pathway, especially the step of pyrrothine acylation, could lead after further studies to yield improvement and to selective production of dithiolopyrrolones with new biological activities.