Purple Colonies Research Articles

Building a baseline for habitat-forming corals by a multi-source approach, including Web Ecological Knowledge

In the Mediterranean, habitat-forming corals often characterize essential fish habitats. While their distribution is sufficiently known for the western basin, few data are available from the Central-Eastern Mediterranean Sea (CEM). This study fills this gap supplying the largest dataset ever built on the geographical and bathymetric distribution of the most relevant habitat-forming corals (Eunicella cavolini, Eunicella verrucosa, Eunicella singularis, Leptogorgia sarmentosa, Paramuricea clavata, Corallium rubrum and Savalia savaglia) of the CEM. Information collected from different sources such as literature, citizen science, and from the World Wide Web (WWW) was combined. Videos published on the WWW provided additional information on the presence of fishing lines and signs of damage, as well as on the distribution of purple and yellow-purple colonies of Paramuricea clavata. The study highlighted the impressive amount of information that the WWW can offer to scientists, termed here as Web Ecological Knowledge (WEK). The WEK is constantly fuelled by internauts, representing a free, refreshable, long-term exploitable reservoir of information. A quick and easy method to retrieve data from the WWW was illustrated. In addition, the distribution of corals was overlapped to marine protected areas and to the distribution of environmental conditions suitable for coralligenous habitats, fragile biogenic Mediterranean structures hosting complex assemblages in need of strict protection. The collected data allowed identifying priority areas with high species diversity and sites that are impacted by fishing activities. Supplied data can correctly address conservation and restoration policies in the CEM, adding an important contribution to ecosystem-based marine spatial planning.

Fatal Cowdriosis (Heartwater) and Trichurosis in a Camel Bull (Camelus dromedarius): a case report

A 5 year old male camel was reported dead in an institutional farm, and a routine postmortem was conducted on it. Adult worms were found in the lumen of the large intestines and segments of all intestines were sent to the parasitology laboratory for helminth identification. Rectal contents were also sent to the laboratory for oocyst screening. Lung and brain samples were also sent to the parasitology laboratory based on history. The result from the parasitology laboratory confirmed a helminth infection known as trichurosis and heartwater infection was also confirmed from presence of purple colonies of Ehrlichia ruminantium on the endothelium of capillaries close to the nuclei. Although it was hard to establish which of the infections caused the death of the animal but it is noteworthy that this case confirms natural susceptibility of the camel to both diseases and is capable of causing mortality in camels.

Phylogenetic assessment and taxonomic revision of Mariannaea

Four new species of Mariannaea were described in this paper, namely M. chlamydospora, M. cinerea, M. fusiformis, and M. lignicola. Mariannaea chlamydospora is characterized by its cream-colored, zonate colonies on PDA, smooth conidiophores, fusiform conidia, and abundant chlamydospores. Mariannaea cinerea forms grey colonies and ellipsoidal to subglobose conidia. Mariannaea fusiformis forms purple colonies and fusiform to subglobose conidia. Mariannaea lignicola has brown conidiophores and broad hyphae. The molecular phylogeny was inferred using ITS, LSU, and TUB-2 loci. The type species of Mariannaea (M. elegans) is epitypified. The variety M. elegans var. punicea is raised to species rank. Mariannaea clavispora is excluded from Mariannaea because of its cylindrical phialides, straight conidial chains and deviating phylogenetic affinity. Mariannaea nipponica did not fit well the generic concept of Mariannaea based on their morphological characters, and its generic placement remains uncertain. A key to the currently accepted 15 species of Mariannaea is provided.

Evaluation of the Usefulness of Selective Chromogenic Agar Medium (ChromID VRE) and Multiplex PCR Method for the Detection of Vancomycin-resistant Enterococci

Accurate and early detection of vancomycin-resistant enterococci (VRE) is critical for controlling nosocomial infection. In this study, we evaluated the usefulness of a selective chromogenic agar medium and of multiplex PCR for detection of VRE, and both these techniques were compared with the conventional culture method for VRE detection. We performed the following 3 methods for detecting VRE infection in stool specimens: the routine culture method, culturing in selective chromogenic agar medium (chromID VRE, bioMérieux, France), and multiplex PCR using the Seeplex® VRE ACE Detection kit (Seegene Inc., Korea) with additional PCR for vanC genes. We isolated 109 VRE strains from 100 stool specimens by the routine culture method. In chromID VRE, all the isolates showed purple colonies, including Enterococcus gallinarum and E. raffinosus, which were later identified using the Vitek card. All VRE isolates were identified by the multiplex PCR method; 100 were vanA-positive E. faecium, 8 were vanA- and vanC-1-positive E. gallinarum, and 1 was vanA-positive E. raffinosus. For VRE surveillance, culturing the isolates in chromID VRE after broth enrichment appears to be an accurate, rapid, and easy method for routine screening test. Multiplex PCR is relatively expensive and needs skilled techniques for detecting VRE, but it can be an auxiliary tool for rapid detection of genotype during a VRE outbreak.

Catheter-related fungemia caused by Candida intermedia

Candida intermedia is rarely reported as a human pathogen. We report two cases of catheter-related fungemia caused by C. intermedia which were treated successfully with intravenous fluconazole and catheter removal. The isolates were identified by commercial biochemical methods, oligonucleotide array, and partial sequencing analysis of rRNA genes.

Compared distribution within a disturbed fishpond ecosystem of breeding ducks and bird species indicators of habitat quality

The distribution of breeding ducks versus three other bird species (Mute Swan Cygnus olor, Black-headed Gull Larus ridibundus and Purple Heron Ardea purpurea) among waterbodies was investigated in the Dombes area, Eastern France, where breeding duck populations have undergone a severe decline following a large-scale transformation of meadow habitat into cropland. Higher Pochard Aythyaferina, Tufted Duck Aythyafuligula, Red-crested Pochard Netta rufina and Gadwall Anas strepera pair densities were recorded in fishponds where Black-headed Gulls were nesting. In these ponds however, nesting success (assessed by the number of broods divided by the number of pairs) was not significantly higher. Similarly, Pochard pair density was higher in ponds with a Purple Heron colony, but brood densities were not. We hypothesise that, in the study region, clutch concentration in the most attractive areas could compensate for the anti-predation effect of gull colonies or overwater nesting in shore vegetation. We could not confirm the expected negative impact of Mute Swan aggressive behaviour on duck distribution. Even though Mallard Anas platyrhynchos pair density was lower in ponds with breeding swans, we did not observe difference for Mallard broods. Moreover, Red-crested Pochard pair density and nesting success were higher in ponds where swans were breeding, probably as a consequence of shared habitat preferences.

The Vacuolar Import and Degradation Pathway Merges with the Endocytic Pathway to Deliver Fructose-1,6-bisphosphatase to the Vacuole for Degradation

The gluconeogenic enzyme fructose-1,6-bisphosphatase (FBPase) is degraded in the vacuole when glucose is added to glucose-starved cells. Before it is delivered to the vacuole, however, FBPase is imported into intermediate carriers called Vid (vacuole import and degradation) vesicles. Here, using biochemical and genetic approaches, we identified a requirement for SEC28 in FBPase degradation. SEC28 encodes the epsilon-COP subunit of COPI (coat protein complex I) coatomer proteins. When SEC28 and other coatomer genes were mutated, FBPase degradation was defective and FBPase association with Vid vesicles was impaired. Coatomer proteins were identified as components of Vid vesicles, and they formed a protein complex with a Vid vesicle-specific protein, Vid24p. Furthermore, Vid24p association with Vid vesicles was impaired when coatomer genes were mutated. Kinetic studies indicated that Sec28p traffics to multiple locations. Sec28p was in Vid vesicles, endocytic compartments, and the vacuolar membrane in various mutants that block the FBPase degradation pathway. Sec28p was also found in vesicles adjacent to the vacuolar membrane in the ret2-1 coatomer mutant. We propose that Sec28p resides in Vid vesicles, and these vesicles converge with the endocytic pathway. After fusion, Sec28p is distributed on the vacuolar membrane, where it concentrates on vesicles that pinch off from this organelle. FBPase also utilizes the endocytic pathway for transport to the vacuole, as demonstrated by its presence in endocytic compartments in the Deltavph1 mutant. Taken together, our results indicate a strong connection between the Vid trafficking pathway and the endocytic pathway.

Distribution and photobiology of Symbiodinium types in different light environments for three colour morphs of the coral Madracis pharensis: is there more to it than total irradiance?

The role of symbiont variation in the photobiology of reef corals was addressed by investigating the links among symbiont genetic diversity, function and ecological distribution in a single host species, Madracis pharensis. Symbiont distribution was studied for two depths (10 and 25 m), two different light habitats (exposed and shaded) and three host colour morphs (brown, purple and green). Two Symbiodinium genotypes were present, as defined by nuclear internal transcribed spacer 2 ribosomal DNA (ITS2-rDNA) variation. Symbiont distribution was depth- and colour morph-dependent. Type B15 occurred predominantly on the deeper reef and in green and purple colonies, while type B7 was present in shallow environments and brown colonies. Different light microhabitats at fixed depths had no effect on symbiont presence. This ecological distribution suggests that symbiont presence is potentially driven by light spectral niches. A reciprocal depth transplantation experiment indicated steady symbiont populations under environment change. Functional parameters such as pigment composition, chlorophyll a fluorescence and cell densities were measured for 25 m and included in multivariate analyses. Most functional variation was explained by two photobiological assemblages that relate to either symbiont identity or light microhabitat, suggesting adaptation and acclimation, respectively. Type B15 occurs with lower cell densities and larger sizes, higher cellular pigment concentrations and higher peridinin to chlorophyll a ratio than type B7. Type B7 relates to a larger xanthophyll-pool size. These unambiguous differences between symbionts can explain their distributional patterns, with type B15 being potentially more adapted to darker or deeper environments than B7. Symbiont cell size may play a central role in the adaptation of coral holobionts to the deeper reef. The existence of functional differences between B-types shows that the clade classification does not necessarily correspond to functional identity. This study supports the use of ITS2 as an ecological and functionally meaningful marker in Symbiodinium.

Evaluation of a Double Layer Agar Plate For Direct Enumeration of Vibrio parahaemolyticus

ABSTRACTA double layer agar plate (DLAP) was developed according to the thin agar layer (TAL) method as a 1‐step procedure for direct enumeration of injured Vibrio parahaemolyticus cells based on the formation of unique purple colonies by V. parahaemolyticus. The DLAP was prepared by overlaying an equal volume (10 mL) of a nonselective medium (tryptic soy agar supplemented with 1.5% NaCl) onto a selective medium (Bio‐Chrome Vibrio medium). The DLAP was capable of detecting V. parahaemolyticus in mixed cultures containing non‐Vibrio bacteria. Production of purple colonies by V. parahaemolyticus on DLAP was not affected by the growth of other bacteria, even when V. parahaemolyticus was only a small fraction (5%) of the entire bacterial population. Direct plating on DLAP was found as effective as the most probable number (MPN) method for recovering heat‐and cold‐injured V. parahaemolyticus cells, which could not be detected by direct plating on Bio‐Chrome Vibrio medium or thiosulfate‐citrate‐bile salts‐sucrose agar. The DLAP offers an alternative to the MPN method for detecting injured V. parahaemolyticus cells and can be used as a simple 1‐step procedure for quick screening of V. parahaemolyticus in foods.

Translation initiation with GUC codon in the archaeon Halobacterium salinarum: implications for translation of leaderless mRNA and strict correlation between translation initiation and presence of mRNA

We have investigated whether anticodon sequence mutant of an archaeal initiator tRNA can initiate protein synthesis using reporter genes carrying mutations in the initiation codon. Halobacterium salinarum was used as the model organism and the bacterio-opsin gene (bop), which encodes the precursor of the protein component of the purple membrane protein bacterio-opsin (Bop), was chosen as the reporter. We demonstrate that a CAU to GAC anticodon sequence mutant of Haloferax volcanii initiator tRNA can initiate Bop protein synthesis using GUC as the initiation codon in H. salinarum. We generated four mutant bop genes, each carrying the AUG to GUC initiation codon mutation, with or without a compensatory mutation to maintain a predicted stem-loop structure at the 5'-end of the bop mRNA, and with or without mutations to test translation initiation at a site corresponding to the amino terminus of mature bacterio-opsin. H. salinarum chromosomal recombinants containing these mutant genes were phenotypically Pum- (purple membrane negative). Upon transformation with a plasmid carrying the mutant initiator tRNA gene, only strains designed to maintain the bop mRNA stem-loop structure produced Bop and were phenotypically Pum+ as indicated by purple colony colour, and immunoblotting and spectral analysis of cell extracts. Thus GUC can serve as an initiation codon in archaea and the stem-loop structure in the bop mRNA is important for translation. Interestingly, for the same mutant mRNA, only transformants that produce Bop protein contain bop mRNA. These results suggest either a strong coupling between translation and mRNA stability or strong transcriptional polarity in H. salinarum.

Characterization of a Forest Soil Metagenome Clone That Confers Indirubin and Indigo Production on Escherichia coli

A microbial community analysis of forest soil from Jindong Valley, Korea, revealed that the most abundant rRNA genes were related to Acidobacteria, a major taxon with few cultured representatives. To access the microbial genetic resources of this forest soil, metagenomic libraries were constructed in fosmids, with an average DNA insert size of more than 35 kb. We constructed 80,500 clones from Yuseong and 33,200 clones from Jindong Valley forest soils. The double-agar-layer method allowed us to select two antibacterial clones by screening the constructed libraries using Bacillus subtilis as a target organism. Several clones produced purple or brown colonies. One of the selected antibacterial clones, pJEC5, produced purple colonies. Structural analysis of the purified pigments demonstrated that the metagenomic clone produced both the pigment indirubin and its isomer, indigo blue, resulting in purple colonies. In vitro mutational and subclonal analyses revealed that two open reading frames (ORFs) are responsible for the pigment production and antibacterial activity. The ORFs encode an oxygenase-like protein and a putative transcriptional regulator. Mutations of the gene encoding the oxygenase canceled both pigment production and antibacterial activity, whereas a subclone carrying the two ORFs retained pigment production and antibacterial activity. This finding suggests that these forest soil microbial genes are responsible for producing the pigment with antibacterial activity.

Selectivity and Specificity of a Chromogenic Medium for Detecting Vibrio parahaemolyticus

The thiosulfate–citrate–bile salts–sucrose agar (TCBS) used in the most-probable-number method for detecting Vibrio parahaemolyticus cannot differentiate growth of V. parahaemolyticus from Vibrio vulnificus or Vibrio mimicus. This study examined the selectivity and specificity of Bio-Chrome Vibrio medium (BCVM), a chromogenic medium that detects V. parahaemolyticus on the basis of the formation of distinct purple colonies on the medium. A panel consisting of 221 strains of bacteria, including 179 Vibrio spp. and 42 non-Vibrio spp., were examined for their ability to grow and produce colored colonies on BCVM. Growth of Salmonella, Shigella, Escherichia coli, Enterobacter cloacae, Yersinia enterocolitica, and Aeromonas was inhibited by both BCVM and TCBS. All 148 strains of V. parahaemolyticus grew on BCVM, and 145 of them produced purple colonies. The remaining 31 Vibrio spp., except one strain of Vibrio fluvialis, were either unable to grow or produced blue-green or white colonies on BCVM. Bio-Chrome Vibrio medium was capable of differentiating V. parahaemolyticus from other species, including V. vulnificus and V. mimicus. Further studies are needed to evaluate the sensitivity and specificity of BCVM for detecting V. parahaemolyticus in foods.

Isolation of Iodide-Oxidizing Bacteria from Iodide-Rich Natural Gas Brines and Seawaters

Iodide-oxidizing bacteria (IOB), which oxidize iodide (I-) to molecular iodine (I2), were isolated from iodide-rich (63 microM to 1.2 mM) natural gas brine waters collected from several locations. Agar media containing iodide and starch were prepared, and brine waters were spread directly on the media. The IOB, which appeared as purple colonies, were obtained from 28 of the 44 brine waters. The population sizes of IOB in the brines were 10(2) to 10(5) colony-forming units (CFU) mL(-1). However, IOB were not detected in natural seawaters and terrestrial soils (fewer than 10 CFU mL(-1) and 10(2) CFU g wet weight of soils(-1), respectively). Interestingly, after the enrichment with 1 mM iodide, IOB were found in 6 of the 8 seawaters with population sizes of 10(3) to 10(5) CFU mL(-1). 16S rDNA sequencing and phylogenetic analyses showed that the IOB strains are divided into two groups within the alpha-subclass of the Proteobacteria. One of the groups was phylogenetically most closely related to Roseovarius tolerans with sequence similarities between 94% and 98%. The other group was most closely related to Rhodothalassium salexigens, although the sequence similarities were relatively low (89% to 91%). The iodide-oxidizing reaction by IOB was mediated by an extracellular enzyme protein that requires oxygen. Radiotracer experiments showed that IOB produce not only I2 but also volatile organic iodine, which were identified as diiodomethane (CH2I2) and chloroiodomethane (CH2ClI). These results indicate that at least two types of IOB are distributed in the environment, and that they are preferentially isolated in environments in which iodide levels are very high. It is possible that IOB oxidize iodide in the natural environment, and they could significantly contribute to the biogeochemical cycling of iodine.

Prevalence of tinea capitis in Ethiopian schoolchildren

The prevalence of dermatophytosis and the spectrum of dermatophyte species were determined in children attending two schools in Addis Ababa, Ethiopia. Demographic and clinico-dermatological data were collected. Specimens were taken for microscopy and culture from all suspected lesions. Dermatophyte species were identified by morphology and biochemical tests, supplemented by sequencing of the rDNA ITS 2 region in selected isolates. From the Biruh Tesfa Elementary School (BTES) 824 students, and from Mount Olive Academy (MOA) all 124 students, were included. In BTES 513 (62.3%) students were clinically diagnosed with dermatophytosis, 463 (90.3 %) of them with tinea capitis. In 200 consecutive samples from BTES, and in 66 from MOA, 75 and 62%, respectively, contained fungal elements at microscopy. From BTES, 163/496 (33%) samples were culture-positive, of which 149 (91.4%) grew with dark purple colonies identified as Trichophyton violaceum, while 244 (49.4%) samples were contaminated. A few strains grew slowly developing white to cream colonies, two were identified as T. verrucosum, and 12 as white T. violaceum. From MOA 44 (66.7%) of samples were culture-positive, 38 (87%) were identified as T. violaceum, and one (2.3%) as T. verrucosum, while 33% showed no growth. Four white isolates of T.violaceum were confirmed by DNA-sequencing. Dermatophytosis was thus diagnosed in 55-62% of children screened at two schools of different socioeconomic standards in the Ethiopian capital. Trichophyton violaceum constituted 87-90% of all isolates. White variants of T. violaceum were diagnosed in 16 cases.

老人ホーム入居者および職員にみられたＴｒｉｃｈｏｐｈｙｔｏｎ ｖｉｏｌａｃｅｕｍ感染症

Six cases of Trichophyton (T.) violaceum infection seen in a nursing home are reported. A 66-year-old female (case 1) was found with tinea corporis on her face, chest and shoulder, associated with black dot ringworm. A KOH examination of hair showed endothrix parasitism. Reddish purple colonies were isolated from the patient on Sabouraud's dextrose agar, and intercalary and terminal chlamydospores were observed on slide culture. PCR-RFLP analysis of the microorganism showed a pattern of T. violaceum type. Therefore, the isolated fungus was identified as T. violaceum, a typical anthropophilic dermatophyte which had spread among residents and staffs easily. Using a mycological method, we examined 59 persons (21 residents and 38 staff members) who had had contact with case 1. The results were as follows. An 85-year-old female (case 2) and an 83-year-old female (case 3) were carriers of T. violaceum. A 23-year-old male (case 4) had tinea corporis on his right forearm due to T. violaceum. A 24-year-old male (case 5) probably had tinea corporis on his right forearm due to T. violaceum. One year after case 1's first visit to our clinic, we observed an 88-year-old female (case 6) of tinea capitis by T. violaceum. It seems that the organism was preserved in surroundings and members of the nursing home. The contagion in our cases could either have been caused by directly touching the person or by sharing their comb. PCR-RFLP analysis was performed within a short time, so that we managed effectively to select a way of treatment and to prevent the infection from spreading.

Trichophyton violaceum infection in three black brothers

Case 1 was a 3-year-old with tinea capitis, while Case 2 was a 5-year-old with kerion celsi. These conditions developed between December 1997 and January 1998 when the patients were living in Canada. Case 3 was a 7-year-old who developed kerion celsi in March 1998 in Japan. For Cases 1 and 2, the referring doctor had detected a fungal infection a few weeks previously, and griseofulvin was administered orally to Case 1 for three weeks and Case 2 for one week prior to consultation at our department. Both Cases 1 and 2 visited our department initially on May 7, 1998 with the causative agent separated from their lesions by the referring doctor respectively. The causative agent was identified as Trycophyton violaceum by our department. KOH-prepared direct microscopy and culture were positive for Case 1, but negative for Case 2. Infected hairs of Case 1 showed a chain of large arthrospores arranged in parallel rows inside the hair. Case 3 visited our department initially on May 21, and T. violaceum was also isolated from this patient's lesion. A reddish purple isolate that was stored for five months after isolation and culture was subcultured using a Sabouraud agar containing thiamin. After two months, brown colonies without red pigment were seen in the reddish purple colonies. Slide culture performed for both colonies showed intercalary and terminal chlamydospores, thus confirming that they were the same fungus. These findings appear to represent the conversion of T. violaceum into T. glabrum.

Root and stem rot of Schefflera arboricola in Brazil, caused by Fusarium solani

Schefflera arboricola (octopus tree; local name cheflerapequena) is an ornamental shrub of the Araliaceae fromTaiwan. In Brazil it is widely used as a pot plant and ingardens. In March 1998, a disease was observedaffecting patches of plants within groups cultivated inthe garden of the Universidade Federal de Vic¸osa inVic¸osa, Minas Gerais. The initial symptoms of leafchlorosis progressed to leaf drop, browning of stemsand death of the above-ground parts. Below-groundobservations showed that a brown necrosis began insecondary roots and advanced to the base of the stems,by which time complete defoliation had occurred. Thebark was shed in plants with advanced necrosis of theroot system.Tissue fragments taken from the internal parts ofdiseased plants at the limit of the necrotic areas weresurface-sterilized and plated on potato dextrose agar(PDA). A Fusarium species was the only fungusobtained, and appeared from most fragments. Single-spore cultures from these colonies were grown oncarnation leaf agar to assist identification (Nelson et al.,1983). The fungus was identified as Fusarium solani,based on its morphology and on the symptoms observedin natural and artificial infections, which are similar tothose of other diseases caused by F. solani. Atypicalcream or purple colonies developed on PDA, althoughcolony colour is influenced by cultural conditions.Conidia from one isolate were produced in a potatodextrose broth shake culture at 278C in the dark. Seven8-month-old S. arboricola plants were inoculated bydipping the roots for 1 min in a suspension containing3 £ 10

Saturation mutagenesis of the TATA box and upstream activator sequence in the haloarchaeal bop gene promoter.

Degenerate oligonucleotides were used to randomize 21 bp of the 53-bp minimal bop promoter in three 7-bp segments, including the putative TATA box and the upstream activator sequence (UAS). The mutagenized bop promoter and the wild-type structural gene and transcriptional terminator were inserted into a shuttle plasmid capable of replication in the halophilic archaeon Halobacterium sp. strain S9. Active promoters were isolated by screening transformants of an orange (Pum- bop) Halobacterium mutant for purple (Pum+ bop+) colonies on agar plates and analyzed for bop mRNA and/or bacteriorhodopsin content. Sequence analysis yielded the consensus sequence 5'-tyT(T/a)Ta-3', corresponding to the promoter TATA box element 30 to 25 bp 5' of the transcription start site. A putative UAS, 5'-ACCcnactagTTnG-3', located 52 to 39 bp 5' of the transcription start site was found to be conserved in active promoters. This study provides direct evidence for the requirement of the TATA box and UAS for bop promoter activity.

Occurrence of Enterococcus spp. in waters.

We studied 630 bacterial strains isolated from surface waters and determined as enterococci on the basis of their growth on Slanetz-Bartley agar in typical colonies. The strains were tested and characterized by several key conventional tests for basic differentiation of enterococci and by commercial test kits. We identified 135 strains of E. foecium (21%), 115 E. faecalis (18%), 30 E. mundtii (5%), 27 E. hirae (4%), 22 E. casseliflavus (3%), 21 E. gallinarum (3%), 17 E. durans-E. hirae complex (3%), 5 E. durans (1%), and 1 strain of E. avium. 150 strains were classified only as Enterococcus sp. (25%) and 107 strains (17%) isolated from Slanetz-Bartley agar were not enterococci. We found that the non-enterococcal group consisted of other Gram-positive cocci and Gram-positive and Gram-negative rods. Based on the identification we tried to find a relation between taxonomic position of isolated strains and their colony morphology on Slanetz-Bartley agar. Our of the total of 523 identified enterococci, 345 strains (66%) formed purple colonies, 136 red colonies (26%), 37 pink colonies (7%) and 5 cream colored colonies (1%). There was no correlation among the color, size or colony morphology and the taxonomic characterization of enterococcal strains.

Expression of the bacterioopsin gene in Halobacterium halobium using a multicopy plasmid.

Bacteriorhodopsin (bR) was expressed in Halobacterium halobium by using a multicopy plasmid containing the bop gene. The plasmid contains pGRB1, a 1.8-kilobase-pair plasmid; a 70-base-pair fragment from ISH11, a recently characterized insertion sequence; and a 1.6-kilobase-pair fragment carrying the bop gene from H. halobium S9. When transformed with this plasmid, a bop- insertion mutant of H. halobium yielded purple (Pum+) colonies. The insertion at the chromosomal bop locus remained intact in transformed cells, indicating that the plasmid bop gene was responsible for the Pum+ phenotype. bR was induced in early stationary phase in both wild-type and transformed cells. The final level of bR in transformed cells was 25-40% of that in wild type. The lower level of expression was presumably due to plasmid instability. Purple membrane purified from transformed strains had absorption and visible CD properties similar to wild type and contained bR in a hexagonal lattice with the same unit-cell dimension as wild type. The structure of bR from wild-type and transformed strains was identical at a resolution of 7.2 A. When reconstituted into vesicles, the purple membrane from wild-type and transformed strains showed similar light-dependent proton-pumping activity.