No abstract

No abstract

Bacterial diversity in sediments at UNESCO World Heritage listed Naracoorte Caves was surveyed as part of an investigation carried out in a larger study on assessing microbial communities in caves. Cave selection was based on tourist accessibility; Stick Tomato and Alexandra Cave (> 15000 annual visits) and Strawhaven Cave was used as control (no tourist access). Microbial analysis showed that Bacillus was the most commonly detected microbial genus by culture dependent and independent survey of tourist accessible and inaccessible areas of show (tourist accessible) and control caves. Other detected sediment bacterial groups were assigned to the Firmicutes, Actinobacteria and Proteobacteria. The survey also showed differences in bacterial diversity in caves with human access compared to the control cave with the control cave having unique microbial sequences (Acinetobacter, Agromyces, Micrococcus and Streptomyces). The show caves had higher bacterial counts, different 16S rDNA based DGGE cluster patterns and principal component groupings compared to Strawhaven. Different factors such as human access, cave use and configurations could have been responsible for the differences observed in the bacterial community cluster patterns (tourist accessible and inaccessible areas) of these caves. Cave sediments can therefore act as reservoirs of microorganisms. This might have some implications on cave conservation activities especially if these sediments harbor rock art degrading microorganisms in caves with rock art.Keywords: caves; tourism; 16S rDNA; denaturing gradient gel electrophoresis factors attracting tourists (Russell & MacLean, 2008;Bastian et al., 2009; Stomeo et al., 2009).Cave microorganisms range from bacterial groups such as Proteobacteria, Actinobacteria, and Firmicutes to yeasts and saprophytic fungus such as Penicillium, Fusarium and Trichurus (Barton & Jurado, 2007;Zhou et al., 2007;Bastian et al., 2009;Portillo et al., 2009a; Jurado et al., 2010; Adetutu et al., 2011; Vaughan et al., 2011). These microbial communities are affected by the geological nature of the caves, prevailing environmental conditions, soil or sediment factors and cave factors (configuration and use) (Ikner et al., 2007; Shapiro & Pringle, 2010; Adetutu et al., 2011). Cave microorganisms in nutrient rich or limited environments (high and low energy caves) are metabolically versatile acquiring energy from cave compounds, gases and by oxidizing metals from rocks. Through these activities, these microorganisms play critical roles in caves' biogeochemical cycles and in the formation of cave features such as stalactites and stalagmites (Barton & Jurado, 2007). This delicate microbial balance can however be disrupted by uncontrolled human access with adverse effects on the cave environment (Bastian et al., 2010).Abstract:

The fungal diversity in areas accessible and not accessible to tourists at UNESCO World Heritage-listed Naracoorte Caves was investigated with culture-dependent and culture-independent techniques for assistance in cave management protocol development. The caves were selected based on tourist numbers and configurations: Stick Tomato (open, high numbers), Alexandra (lockable openings, high numbers) and Strawhaven (control; no access). Culture-based survey revealed Ascomycota dominance irrespective of sampling area with Microascales (Trichurus sp.) being most frequently isolated. Some Hypocreales-like sequences belonging to Fusarium sp., Trichoderma sp. and Neonectria sp. (Stick Tomato) were cultured only from areas not accessible to tourists. These orders also were detected by DGGE assay irrespective of sampling area. The predominance of Ascomycota (especially Microascales) suggested their important ecological roles in these caves. Culture-independent analysis showed higher Shannon fungal diversity values (from ITS-based DGGE profiles) in tourist-accessible areas of these caves than in inaccessible areas with the fungal community banding patterns being substantially different in Stick Tomato Cave. Further investigations are needed to determine the cause of the differences in the fungal communities of Stick Tomato Cave, although cave-related factors such as use, configuration and sediment heterogeneity might have contributed to these differences.

Lignocellulosic waste (LCW) is an abundant, low-cost, and inedible substrate for the induction of lignocellulolytic enzymes for cellulosic bioethanol production using an efficient, environmentally friendly, and economical biological approach. In this study, 30 different lignocellulose-degrading bacterial and 18 fungal isolates were quantitatively screened individually for the saccharification of four different ball-milled straw substrates: wheat, rice, sugarcane, and pea straw. Rice and sugarcane straws which had similar Fourier transform-infrared spectroscopy profiles were more degradable, and resulted in more hydrolytic enzyme production than wheat and pea straws. Crude enzyme produced on native straws performed better than those on artificial substrates (such as cellulose and xylan). Four fungal and five bacterial isolates were selected (based on their high strawase activities) for constructing dual and triple microbial combinations to investigate microbial synergistic effects on saccharification. Combinations such as FUNG16-FUNG17 (Neosartorya fischeri-Myceliophthora thermophila) and RMIT10-RMIT11 (Aeromonas hydrophila-Pseudomonas poae) enhanced saccharification (3- and 6.6-folds, respectively) compared with their monocultures indicating the beneficial effects of synergism between those isolates. Dual isolate combinations were more efficient at straw saccharification than triple combinations in both bacterial and fungal assays. Overall, co-culturing can result in significant increases in saccharification which may offer significant commercial potential for the use of microbial consortia.

Aims: To provide an independent assessment of azoxystrobin effects on nontarget soil bacteria and fungi and generate some baseline information on azoxystrobin's persistence in soil. Methods and Results: Plate based assay showed that azoxystrobin exhibited differential toxicity upon cultured fungi at different application rates. While 14C labelled isotopes experiments showed that less than 1 of azoxystrobin was mineralized, degradation studies revealed over 60 azoxystrobin breakdown over 21 days. PCR DGGE analysis of 16S and 18S rRNA genes from different soil microcosms showed that azoxystrobin had some effects on fungal community after 21 days (up to 84 days) of incubation in either light or dark soil microcosms. Light incubations increased fungal diversity while dark incubations reduced fungal diversity. Bacterial diversity was unaffected. Conclusions: Significant biotic breakdown of parent azoxystrobin occurred within 21 days even in the absence of light. Azoxystrobin under certain conditions can reduce fungal soil diversity. Significance and Impact of the Study: One of the few independent assessments of azoxystrobin (a widely used strobilurins fungicide) effects on soil fungi when used at the recommended rate. Azoxystrobin and metabolites may persist after 21 days and affect soil fungi. © 2008 The Authors

No abstract

No abstract