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Designing of new antimicrobial drugs is always needed to solve the problem of continue resistance emerging among microorganisms against antibiotics already in use. Microorganisms from unusual environments, such as reported from the surface and inside of rocks are a repository of certain metabolites that might be able to solve the problem of increasing resistance against antibiotics. The present study was designed to isolate endolithic and epilithic bacterial strains from the rapidly weathering rocks collected from Nathiagali, Pakistan to characterize and screen them for antimicrobial activity. The isolates were identified based on 16S rRNA sequence analysis. Antibacterial activity of the isolates was checked against ATCC strains E. coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Seven different types of antibiotic discs were used to check the intrinsic resistance of all the isolates to various antibiotics. Interestingly, most of the isolates were found resistant while only a few were susceptible, however, the isolates Lysinibacillus spp. N40 and Brevundomonas spp. P20 showed no activity at all. Increased levels of resistance to heavy metals such as; iron, arsenic, cadmium, chromium, and nickel were shown by strains like; Alcaligenes spp. N14 and N21, Bordetella spp. N30 and Streptomyces spp. N28. Alcaligenes spp. N27 and Lysinibacillus spp. P17 showed strong activity against all the three ATCC strains. The study concludes that the bacteria isolated from the rocks having substantial resistance to heavy metals are also showing good antibacterial activity as well as, and they are also potential candidates for the applications in pharmaceutical as well as environmental research. [ABSTRACT FROM AUTHOR]

Cultureable bacterial diversity of previously unexplored Siachen glacier, Pakistan, was studied. Out of 50 isolates 33 (66%) were Gram negative and 17 (34%) Gram positive. About half of the isolates were pigment producers and were able to grow at 4–37°C. 16S rRNA gene sequences revealed Gram negative bacteria dominated by Proteobacteria (especially γ-proteobacteria and β-proteobacteria) and Flavobacteria. The genus Pseudomonas (51.51%, 17) was dominant among γ- proteobacteria. β-proteobacteria constituted 4 (12.12%) Alcaligenes and 4 (12.12%) Janthinobacterium strains. Among Gram positive bacteria, phylum Actinobacteria, Rhodococcus (23.52%, 4) and Arthrobacter (23.52%, 4) were the dominating genra. Other bacteria belonged to Phylum Firmicutes with representative genus Carnobacterium (11.76%, 2) and 4 isolates represented 4 genera Bacillus, Lysinibacillus, Staphylococcus and Planomicrobium. Most of the Gram negative bacteria were moderate halophiles, while most of the Gram positives were extreme halophiles and were able to grow up to 6.12 M of NaCl. More than 2/3 of the isolates showed antimicrobial activity against multidrug resistant S. aureus, E. coli, Klebsiella pneumonia, Enterococcus faecium, Candida albicans, Aspergillus flavus and Aspergillus fumigatus and ATCC strains. Gram positive bacteria (94.11%) were more resistant to heavy metals as compared to Gram negative (78.79%) and showed maximum tolerance against iron and least tolerance against mercury. [ABSTRACT FROM AUTHOR]

Bacterial strains having the ability to inhibit the growth of other bacteria were isolated from soil samples collected from Kashmir Smast (smast is Pushto for cave), Khyber Pakhtunkhwa, Pakistan. The study includes mineralogical and geochemical analyses of soil sample collected from the cave, so as to describe the habitat from which the microorganisms have been isolated. Total bacterial count of the soil sample was 5.25 × 104 CFU mL-1. Four bacterial isolates having activity against test organisms Micrococcus luteus, Klebsiella sp., Pseudomonas sp., and Staphylococcus aureus were screened out for further study. Two of the isolates were found to be Gram-positive and the other two Gram-negative. The four isolates showing antibacterial activity were identified as Serratia sp. KC1-MRL, Bacillus licheniformis KC2-MRL, Bacillus sp. KC3-MRL, and Stenotrophomonas sp. KC4-MRL on the basis of 16S rRNA sequence analysis. Although all isolates showed antibacterial activity, only Bacillus licheniformis KC2-MRL was selected for further study due to its large zone of inhibition. Antibacterial activity of B. licheniformis KC2-MRL was optimum when grown in nutrient broth adjusted to pH 5 and after 24 hours of incubation at 35 uC. The extracted antibacterial compound was stable at pH 5-7 and 40 uC when incubated for 1 hour. The strain was found resistant against cefotaxime (ctx). Atomic-absorption analysis of the soil sample collected from the cave showed high concentrations of calcium (332.938 mg kg-1) and magnesium (1.2576 mg kg-1) compared to the control soil collected outside the cave. FTIR spectrum of the concentrated protein showed similarity to bacitracin. The antibacterial compound showed activity against both Gram-negative and positive test strains. Mineralogy of Kashmir Smast is diverse and noteworthy. Different geochemical classes identified by X-ray diffraction were nitrates, oxides, phosphates, silicates, and sulfates. Weathered cave limestone contributes notably to the formation of these minerals or compounds. FTIR spectroscopic analysis helped to identify minerals such as quartz, clinochlore, vermiculite, illite, calcite, and biotite. [ABSTRACT FROM AUTHOR]

β-Lactam antimicrobial agents represent the most common treatment for bacterial infections and continue to be the leading cause of resistance to β-lactam antibiotics among Gram-negative bacteria worldwide. The persistent exposure of bacterial strains to a multitude of β-lactams has induced dynamic and continuous production and mutation of β-lactamases in these bacteria, expanding their activity even against the newly developed β-lactam antibiotics. These enzymes are known as extended-spectrum β-lactamases (ESBLs). The majority of ESBLs are derived from the widespread broad-spectrum β-lactamases TEM-1 and SHV-1. There are also new families of ESBLs, including the CTX-M and OXA-type enzymes as well as novel unrelated β-lactamases. In recent years, there has been an increased incidence and prevalence of ESBLs. ESBLs are mainly found in strains of Escherichia coli and Klebsiella pneumoniae but have also been reported in other Enterobacteriaceae strains and Pseudomonas aeruginosa. Infections with ESBL-producing bacterial strains are encountered singly or in outbreaks, especially in critical care units in hospitals, resulting in increasing cost of treatment and prolonged hospital stays. Not only may nursing home patients be an important reservoir of ESBL-containing multiple antibiotic-resistant organisms, but ambulatory patients with chronic conditions may also harbor ESBL-producing organisms. [Copyright &y& Elsevier]