Analysis of Salt-Containing Biofilms on Limestone Buildings of the Mayan Culture at Edzna,Mexico

Biofilms on the salted ceiling of a limestone tunnel at the Mayan site of Edzna, Mexico, were characterised using SEM, EDS, chemical analysis, light microscopy, culture and pigment analysis. Major superficial biomass was pigmented, scytonemin-rich Subsection II cyanobacteria. Main endolithic phototrophs were Subsection I and II cyanobacteria and the alga Nanochlorum. Bacteria and actinomycetes of the Geodermatophilus, nocardioform, and streptomycete groups were present at all levels. Salt crystals, mainly sulfates, were found throughout the stone. Microbial ion transport, metabolite production, chelation, and water retention caused degradation and salt deposits. Exfoliation is the major erosion process.     

Occurrence and significance of precipitating antibodies against thermophilic actinomycetes in the sera of dairy herd workers,Nangali, Delhi

The study was prompted by the lack of information on the role of thermophilic actinomycetes in hypersensitivity pneumonitis in India. It reports the occurrence of precipitating antibodies against clinically important thermophilic actinomycetes in the sera of a population sample of dairy herd workers, Nangali, Delhi. Of 112 workers investigated, 28 (25%) showed precipitins againstFaenia rectivirgula, 4 (3.2%) againstSaccharomonospora viridis, 2 againstThermoactinomyces thalpophilus and one each againstT. vulgaris andT. sacchari. The results of enzyme-linked immunosorbent assay (ELISA) indicated that IgG antibody activity againstF. rectivirgula was significantly higher in the symptomatic group than in the asymptomatic group (p<0.05) of workers and the controls (p<0.01). Significant difference inF. rectivirgula IgG activity was also obtained between the precipitin-positive symptomatic group and the precipitin-positive asymptomatic group (p< 0.05). In strong contrast, the IgG antibody activity againstT. thalpophilus was found to be uniformly low. A limited aeromicrobiological sampling of the dairy farm revealedS. viridis (55.8%) to be the commonest species followed byT. vulgaris (19.2%),T. thalpophilus (18.5%),F. rectivirgula (5%) andT. sacchari (15%). On the basis of suggestive clinical and laboratory findings, farmer's lung disease was suspected in four dairy herd workers. A comprehensive clinical evaluation including pulmonary function studies on the dairy herd workers and their long-term follow-up is indicated to determine the extent of respiratory morbidity caused byF. rectivirgula, S. viridis, T. thalpophilus, T. sacchari andT. vulgaris in India.     

Colonization of plant rhizosphere by actinomycetes of different genera

The survival of environmental isolates of actinomycetes introduced with the seeds of agricultural plants in root-free soil and in the rhizosphere and rhizoplane was studied. Different strategies of colonization of the rhizosphere were revealed for the representatives of the genera Streptomyces, Micromonospora, and Streptosporangium, organisms typical for the moderate climate rhizosphere. The plants of winter rye (Secale cereale L.) inoculated with actinomycetes were shown to have growth advantages, while the cow clover plants (Trifolium pratense L.) had no growth advantages compared to uninoculated plants. The role of the plant component in the interaction with mycelial prokaryotes is discussed.     

Jiangchuanmycin,a New Pyrrolizidine Analog from Streptomyces sp. YIM S01863

Jiangchuanmycin ( 1 ), a new indole containing pyrrolizidine, and six known peptides ( 2–7 ) were obtained from the fermentation broth of a Streptomyces isolate collected from a sediment sample of Xingyun Lake, Jiangchuan, China. Their structures were elucidated on the detailed analysis of the HR-ESI-MS, 1D and 2D NMR, ECD, and X-ray crystallographic data. Jiangchuanmycin ( 1 ) presented weak inhibitory effects on cell lines of H1299, MHCC97H, HCT116 with the IC₅₀ values of 97.6 μM, 98.6 μM and 40.6 μM, respectively.     

Diversity in aminoglycoside antibiotic resistance of actinomycetes and its exploitation in the search for novel antibiotics

Wide varieties of multiple aminoglycoside antibiotic (AG) resistance that are not found in knownStreptomyces cultures were found among actinomycetes isolated as AG-resistant. Screening of about 170 AG-resistant isolates demonstrated their high probability (63%) of antibiotic production including the production of eight different AGs. We found specific AG-resistance patterns correlating to the productivity of specific AGs and established an AG-targeted assay system using AG producers as test organisms. Consequently, AG-directed screening totally on the basis of multiple AG-resistance was established. Necessity of biochemical and genetic studies on primary metabolism in order to find a new basis to search for novel metabolites is also discussed.     

Bioleaching of Uranium From Egyptian Rocks Using Native Actinomycete Strains

Bioleaching is an economic, novel practice for extraction of metals from their sources by microorganisms. The current study aimed to extract uranium from Egyptian ores using native strains of actinomycetes. Two types of rocks and one ore sample were collected from west-central Sinai, Egypt. Major oxides of the samples and fourteen heavy metals, including uranium, were determined. X-ray diffraction analysis proved that uranium was present in the samples in various structures. Uranium was present in different concentrations, 220, 770, and 550 mg/kg in sandstone, granite, and manganese ore, respectively. Thirty-four actinomycete isolates were recovered from the studied samples using four different isolation media. Acid production capabilities were employed to select isolates for further leaching experiments. Bioleaching experiments were carried out using sterile and non-sterile ore samples. Using sterile ore samples, the highest solubilization percentages of U₃O₈ were 44.5, 38.55, and 16.76% from sandstone, manganese ore, and granite sample, achieved by isolates UA12, UA5, and U7, respectively. Lower solubilization percentages of U₃O₈ were recorded by using non-sterile ore samples. Investigating the factors affecting the bioleaching abilities of the tested organisms revealed that 10 days of incubation with 4% pulp density were the best conditions for U₃O₈ solubilization. The most efficient isolates were identified using 16S rRNA gene sequence analysis. UA12 identified to be Streptomyces bacillaris, while UA5 could not be identified, and U7 was assigned as uncultured bacterium clone. Scanning electron microscope examination of the bioleaching experiment showed different growth intensity within the active isolates. For larger-scale extraction purposes, a kilogram of sandstone, containing 220 mg of U₃O₈, was used in the form of a truncated cone in a heap leaching experiment. After 20 cycles, 14.72 mg/l (6.7%) of U₃O₈ was leached by S. bacillaris, while 19.36 mg/l (8.8%) of U₃O₈ was leached by chemical leaching using sulfuric acid. The results of this study prove that the extraction of uranium using actinomycetes could be exploited as less polluting, more economical, and more effective than traditional chemical extraction especially from low-grade ores or mining wastes.     

Production of bioactive metabolites by Nocardia levis MK-VL_113

Aims: To isolate and identify the bioactive compounds produced by Nocardia levis MK‐VL_113. Methods and Results: Cultural characteristics of Noc. levis isolated from laterite soils of Guntur region were recorded on International Streptomyces Project media. Morphological studies of the strain through scanning electron microscopy revealed the clear pattern of its hyphal fragmentation into rod‐shaped bacilli. Chemical examination of the secondary metabolites of the strain grown on sucrose–tryptone broth led to the isolation of three fractions active against Bacillus cereus. Further analysis of second fraction resulted in the isolation of two active subfractions. Two different phthalate esters, namely, bis‐(2‐ethylhexyl) phthalate and bis‐(5‐ethylheptyl) phthalate, were purified from the first active subfraction, and the structural elucidation of these compounds was confirmed on the basis of FT‐IR, mass and NMR spectroscopy. The partially purified second subfraction subjected to Gas Chromatography–Mass spectroscopy contained nine components: decanedioic acid; 2,6‐piperdione monooxime; 1‐eicosanol; beta‐1‐arabinopyranoside, methyl; cyclopentaneundecanoic acid; hexadecanoic acid; silane, trichloro eicosyl; 1‐hexacosanol; and 1,2‐dodecanediol. The antimicrobial activity of the bioactive compounds produced by Noc. levis was expressed in terms of minimum inhibitory concentration. Conclusions: The present study clearly revealed that the metabolites of Noc. levis act as bioactive compounds against Gram‐positive and Gram‐negative bacteria, yeast and filamentous fungi. It also supports the idea that there are a number of rare actinomycetes remained to be explored for new bioactive compounds. Significance and Impact of the Study: Metabolites of Noc. levis exhibited antibacterial and antifungal activities. This is the first report of bis‐(5‐ethylheptyl) phthalate as well as the nine partially purified compounds from actinomycetes. In addition, this is also the first report of bis‐(2‐ethylhexyl) phthalate from the genus Nocardia.     

A survey of soil microorganisms,with particular reference to the actinomycetes as sources of substances toxic to Heliothis virescens

Cultures of microorganisms isolated from cultivated soils were grown in submerged fermentation in test tubes kept on a rotary shaker at 28°C for 5 days using a fermentation medium composed primarily of soybean flour and dextrose. The beers were harvested and centrifuged, and the supernatants were incorporated at a dilution of 1:10 into artificial diets on which neonate larvae of Heliothis virescens were allowed to feed ad libitum for 7 days. If the beer killed or markedly retarded the development of at least 50% of the test larvae, the culture was regrown in shaken cultures in 500-ml Erlenmeyer flasks and assayed again. If a culture produced toxic beers in both fermentations, it was considered active. Over 2100 soil isolates were tested, of which an estimated 95% were actinomycetes. Slightly over 0.4% of the isolates were active, all of which, probably due to our selection procedure, were actinomycetes.