High Pressure Liquid Chromatographic Determination of Bacitracin in Premix Feeds and Finished Feeds: Collaborative Study

A liquid chromatographic technique for the determination of bacitracin in finished feeds and premix feeds consists of an isocratic reverse phase, ion-suppressed technique. The chromatography can be completed in less than 25 min. In a collaborative study involving 9 laboratories and 3 samples of bacitracin methylene disalicylic acid and 3 samples of bacitracin zinc premixes covering the range of 10-50 g/lb, the repeatability standard deviation was 0.55, and the reproducibility standard deviation was 1.35. The average recovery of the bacitracin was 102.0%. The method has been adopted official first action for bacitracin in premix feeds.

A short work-flow to effectively source faecal pollution in recreational waters - A case study

Microbial pollution of recreational waters poses a significant public health risk which, unless mitigated, will continue to increase with population growth. Water managers must implement strategies to accurately discriminate and source human from animal faecal contamination in complex urbanised environments. Our case-study used a new combination of chemical (i.e. ammonia) and microbial (i.e. Escherichia coli, Bacteroides spp.) faecal monitoring tools in a targeted multi-tiered approach to quickly identify pollution hot-spots and track high-risk subterranean stormwater drains in real-time. We successfully located three point sources of human faecal pollution (both episodic and constant pollution streams) within 11 catchments in a total monitoring time of four months. Alternative approaches for obtaining such fine-scale accuracy are typically labour intensive and require expensive equipment.

Detritivores as indicators of landscape stress and soil degradation

Detritivores are small- to medium-sized invertebrates that comminute and break down organic materials such as leaves, twigs and roots, especially within or upon the soil surface, or nearby. Detritivores constitute the majority of the invertebrate biomass pyramid in most environments and provide a key role in organic matter turnover; they also provide alternative food for polyphagous predators that can be active in pest control on crops. Many arthropod taxa are detritivores in soil and litter layers. Here, we focus on the bioindicator potential of three key detritivore groups: slaters, millipedes and oribatid mites. There are possibly 300 species of slaters (terrestrial isopods or Oniscidea) in Australia with 13 of these being introduced, mostly from north-western Europe. These non-native species are the dominant species in disturbed environments such as intensively managed forests and agricultural fields. Slaters are promising indicators of landscape disturbance, soil contamination and tillage. Millipedes are potentially important indicators of stress in agricultural landscapes, given their sensitivity to litter and soil moisture gradients and to physical and chemical perturbations. However, because there is a close association between the millipede fauna and moist plant communities in Australia, they are generally absent from drier landscapes and, therefore, their use as bioindicators in agricultural environments here is problematic. An exception to this association is the increasingly ubiquitous introduced Black Portuguese millipede. This species is tolerant of much drier conditions than most natives, and is likely to change the nature of nutrient cycling processes in pastures and native grasslands in much of southern Australia. Oribatid mites are present in all Australian terrestrial ecosystems. The few studies that have examined their response to disturbance and land use in Australia are consistent with the body of work conducted outside Australia. This consistent response means that the oribatids may be developed as indicators in agricultural, pasture and forested environments. However, the paucity of information on oribatids over appropriate spatial scales in Australia makes the use of this group extremely difficult at this time.