A s the notion that some bacteria live in structurally complex, multicellular communities gains momentum, let us pause to collect our thoughts. Many microbiologists consign organisms with complex structures or behaviors as "weird" and outside the mainstream. Thus, microbiologists who focus on Escherichia coli K-12 acknowledge the complexities of Myxobacteria and Beggiatoa but may not spend much time thinking about them! When we see a particular structure or behavior in one organism, we really should look for this structure or behavior throughout the domain. Woody Hastings and Ken Nealson described signal-controlled luminescence in marine vibrios in 1977. However, another two decades elapsed before Peter Greenberg, now at the University of Washington in Seattle, and Barbara Iglewski at the University of Rochester in Rochester, N.Y., established that cell-cell signaling is critical throughout the bacterial domain, and even longer for our group to recognize that such signals help to control bacterial community development. Now we can search for genetic homologies "in silico," enabling us to search more efficiently for common molecular mechanisms anywhere within microbiology. Structured Microbial Communities Come in Many Forms When individual cells of a single species such as Myxobacteria aggregate, they may produce macroscopic communities (Microbe, January 2007, p. 18). However, many natural biofilms typically are featureless until viewed with light microscopes. These magnified views reveal microcolonies in an English garden of topiary Summary • Microbial species reproducibly form regular structures, including "honeycombs" and "veils" that can grow to macroscopic sizes.

The phenolic antioxidants, gallic acid, vanillic acid, protocatechuic acid, 4-hydroxybenzoic acid, catechin, caffeic acid, and chlorogenic acid were studied for their effects on ochratoxin A (OTA) production and fungal growth of ochratoxigenic Aspergilli. Of the 12 strains tested, which included A. alliaceus, A. lanosus, A. ochraceus, A. albertensis, A. melleus, A. sulphureus, A. carbonarius, A. elegans, and A. sclerotiorum, the greatest inhibition of OTA production was seen in A. sulphureus, A. elegans, and A. lanosus. Vanillic acid and 4-hydroxybenzoic acid were the most inhibitory to both OTA production and growth of most of the strains tested. However, A. ochraceus was not inhibited by either compound, and A. carbonarius was not inhibited by vanillic acid. The effect of each compound on OTA production and growth differed among strains and generally was variable, suggesting that species-specific OTA production and response to phenolic compounds may be influenced by different ecological and developmental factors. In addition, inhibition of OTA production by antioxidant compounds may be useful in determining biosynthetic and regulatory genes involved in both OTA production and stress response in ochratoxigenic Aspergilli.

BackgroundMicrobial biofilms represent an incompletely understood, but fundamental mode of bacterial growth. These sessile communities typically consist of stratified, morphologically-distinct layers of extracellular material, where numerous metabolic processes occur simultaneously in close proximity. Limited reports on environmental isolates have revealed highly ordered, three-dimensional organization of the extracellular matrix, which may hold important implications for biofilm physiology in vivo.ResultsA Pseudomonas spp. isolated from a natural soil environment produced flocculent, nonmucoidal biofilms in vitro with unique structural features. These mature biofilms were made up of numerous viable bacteria, even after extended culture, and contained up to 50% of proteins and accumulated 3% (by dry weight) calcium, suggesting an important role for the divalent metal in biofilm formation. Ultrastructurally, the mature biofilms contained structural motifs consisting of dense, fibrillary clusters, nanofibers, and ordered, honeycomb-like chambers enveloped in thin sheets.ConclusionMature biofilms contained living bacteria and were structurally, chemically, and physiologically heterogeneous. The principal architectural elements observed by electron microscopy may represent useful morphological clues for identifying bacterial biofilms in vivo. The complexity and reproducibility of the structural motifs observed in bacterial biofilms appear to be the result of organized assembly, suggesting that this environmental isolate may possess ecological advantages in its natural habitat.

Aims:  To determine incidence and levels of ochratoxin A (OTA) in California raisins and to isolate and characterize OTA‐producing fungi from California raisin vineyard populations. Methods and Results:  Forty raisin clusters sampled from four California vineyards in the San Joaquin Valley were analysed for OTA content using immunoaffinity and HPLC methods. OTA was detected in 93% of the samples, at levels from 0·06 to 11·4 ng g−1. From these raisin samples, a total of 400 strains of Aspergillus were isolated and analysed for OTA production. Twelve isolates (3%), from five raisin samples, produced OTA. These isolates were identified as Aspergillus carbonarius, based on morphological characteristics and multilocus sequence analysis. Levels of OTA produced by these isolates on raisin agar ranged from 0·9 to 15 μg g−1. Conclusions:  OTA is a common contaminant of raisin vineyards, but average levels are much lower than EU regulatory limits for dried fruit. The primary species responsible for OTA contamination in California raisins is A. carbonarius. Significance and Impact of the Study:  This study illustrates that low‐level OTA contamination of raisins occurs in California and that ecological studies of A. carbonarius within the Aspergillus section Nigri population on raisins are warranted to monitor ochratoxigenic potential of the crop.